Surface electronic properties of tungsten, tungsten carbide, and platinum.

The local electronic structures of the surface regions of tungsten, tungsten carbide, and platinum have been compared. Contrary to the hypothesis that the platinum-like catalytic activity of tungsten carbide results from the contribution of carbon valence electrons to the 5d band of tungsten, the width of the unfilled portion of the d band increases on going from tungsten to tungsten carbide.

Combined treatment with chemotherapy and neutron irradiation for limited non-small-cell lung cancer: a Southwest Oncology Group Study.

Seventy-three patients with regional, inoperable non-small-cell lung cancer received treatment with initial chemotherapy for two cycles (vinblastine-mitomycin followed in 3 weeks by vinblastine-cisplatin), with planned subsequent neutron irradiation to the primary site and concurrent, elective whole-brain irradiation using photons, followed by two more cycles of identical chemotherapy. Histology was reported as adenocarcinoma or large cell in 75%, and 60% had Radiation Therapy Oncology Group (RTOG) stage 3 disease; the remainder had stage 4. The response rate to chemotherapy induction was 51%. There were 58 patients in a second phase of the study who were potentially eligible for treatment with a medically dedicated cyclotron having more favorable characteristics with regard to treatment planning and dose delivery (neutrons "B"). The overall response rate in this group was 79%. Chemotherapy toxicity included four fatalities (5%), with three related to mitomycin C induced bilateral pneumonitis, and an additional five patients (7%) with life-threatening events that required hospitalization. Two fatalities were attributed to combined effects of chemotherapy and radiation, and six more to chest radiation therapy, for an overall treatment-related death incidence of 12 of 73 (16%). Four of the six deaths related to chest irradiation occurred after treatment with a "physics-based" neutron generator (neutrons "A"). Among the 45 who received neutrons in the B group, two (4%) had radiation-related deaths, and another four (10%) had clinically evident radiation pneumonitis. Pretreatment performance status (PS) and response to chemotherapy, but not RTOG stage or weight loss, were significantly associated with survival. Among patients who actually received chest irradiation, only initial response to chemotherapy remained as a significant predictor of survival in univariate analysis, with a median survival of 20 months in responders v 9 months in chemotherapy nonresponders. The patterns of first relapse observed in B group patients revealed that 28% were distant, while 64% were locoregional. This represents a reversal of the usual pattern in studies of chest irradiation alone. It probably reflects elimination of brain relapse by the use of elective whole-brain irradiation, impact of systemic chemotherapy on micrometastases elsewhere, and conservative treatment volumes employed for the chest irradiation in an attempt to minimize its toxicity. Further exploration of combined modality therapy is indicated for regional non-small-cell disease, with a real potential for survival impact if the therapeutic index can be improved.

The use of neutrons in cancer therapy: a historical perspective through the modern era.

The fields of boron neutron capture therapy (BNCT) and fast neutron radiotherapy are surveyed starting with the early clinical work that began shortly after the discovery of the neutron by Chadwick in 1932. The evolution of each field is described and the current status in regards to accepted clinical indications and ongoing research areas summarized. BNCT remains a research area but a discussion is given of current efforts to design and construct non-reactor-based epithermal neutron sources to deploy this technology to major medical centers if the clinical research proves successful. Fast neutron radiotherapy is a mature field with selected clinical indications for locally advanced salivary gland tumors and inoperable sarcomas of bone and soft tissue. The current status of clinical trials for locally advanced prostate cancer and other tumors is reviewed. Ongoing areas of research in the field of fast neutron radiotherapy are described.

Radiation Therapy Oncology Group (RTOG) studies in head and neck cancer.

Since its foundation in 1971, the RTOG has conducted a successful clinical research program in head and neck mucosal squamous cell carcinoma with 22 treatment protocols and one registry study which combined have accumulated data on over 5,500 patients. The RTOG was the first multicenter group to evaluate neoadjuvant chemotherapy before definitive radiation with its methotrexate study. Although the study was negative, RTOG has since conducted five pilot or phase II studies of neoinduction or concurrent chemotherapy with radiation therapy in patients with inoperable tumors. The last study showed that radiation concurrent with cisplatinum was tolerable with a suggestion of increased antitumor effect. In patients with potentially resectable tumors, RTOG has completed a pilot study of combination chemotherapy administered either before or after the surgery with radiotherapy. Based upon its findings, the treatment sequence, surgery-chemotherapy-radiotherapy, was chosen as the experimental arm for a new phase III study. This study was subsequently adopted by the head and neck intergroup mechanism as its study (INT 0034/RTOG 8503). RTOG has investigated the optimal timing of radiotherapy with surgery. The 7303 study established that postoperative radiotherapy achieved significantly better locoregional control but not improved absolute survival. Approximately 30% of the patients on each arm failed to complete both modalities. Even when comparison is restricted to patients who completed both modalities, postoperative radiotherapy still produced the better locoregional control. Efforts to overcome the limitations imposed by tumor hypoxia through use of carbogen (95% O2 and 5% CO2) breathing or the radiosensitizer misonidazole during radiotherapy have been unsuccessful. In a phase I study, RTOG showed that 15 to 18 sessions of sensitized radiation can be safely delivered with the new radiosensitizer SR 2508 in contrast to only six such sessions with misonidazole. This promising radiosensitizer is now being tested in a phase III trial. RTOG has also investigated variations in fraction size, fraction number, and total radiation dose. In the 7102 study, split-course irradiation achieved equivalent antitumor results as compared to continuous daily irradiation but with less social alteration and cost to the patient. In the hyperfraction pilot study 7703, twice a day irradiation with 120 cGys up to 6,000 cGys proved to be tolerable.(ABSTRACT TRUNCATED AT 400 WORDS)

Boron neutron capture therapy (BNCT) for high-grade gliomas of the brain: a cautionary note.

PURPOSE/OBJECTIVE: Boron neutron capture therapy (BNCT) is a method of treating high-grade gliomas of the brain that involves incorporating 10B into the tumor using appropriate pharmacological agents and then irradiating the tumor with thermal or epithermal neutron beams. To date, over 120 patients have been treated in this manner by Japanese investigators using a thermal neutron beam from a nuclear reactor. Favorable reports on outcome have motivated considerable current research in BNCT. The purpose of this study is to provide an independent analysis of the Japanese data by identifying the subset of patients from the United States who received this treatment in Japan and comparing their outcomes relative to a matched cohort who received conventional therapy in various Radiation Therapy Oncology Group (RTOG) studies. METHODS AND MATERIALS: The principal referral sources of patients to Japan for BNCT were identified and the names of patients sent for treatment obtained. The treating physicians in Japan were also contacted to see if additional patients from the United States had been treated. Either the patients or their next of kin were contacted, and permission was obtained to retrieve medical records including tumor pathology for central review. Prognostic variables according to an analysis of the RTOG brain tumor database by Curran et al. were determined from these records and used to construct a matched cohort of patients treated conventionally. RESULTS: A total of 14 patients were identified who had traveled to Japan for BNCT treatment between July, 1987 and June, 1994. In the case of one patient (deceased), it was not possible to contact the next of kin. Material was obtained on the other 13 patients and review of the pathology indicated that 1 patient had a central nervous system lymphoma rather than a high-grade glioma. Survival data was analyzed for the other 12 patients on an actuarial basis, and this showed no difference compared to survival data for a matched set of patients constructed according to the classification schema of Curran et al. Median survivals were 10.5 months for both groups; survival at 3 years was 22% for the BNCT group compared to 13% for the conventionally treated group (p = NS). The only long-term survivors in the BNCT group had anaplastic astrocytomas and favorable prognostic criteria (Classes I and II of Curran et al.). The actuarial survival curves for the patients with glioblastoma multiforme (strict histological criteria) who received BNCT and their counterparts who received conventional therapy are virtually superimposable. The respective 2-year survivals are 20 vs. 10% (p = NS). Patterns of failure, toxicity, and analysis of the results according to histology are discussed. CONCLUSIONS: Analysis of patients from the United States who received BNCT treatment in Japan does not support a clinically meaningful improvement in survival attributable to this form of therapy. The implications of this for future BNCT research directions are discussed.

Fast neutron radiotherapy for soft tissue and cartilaginous sarcomas at high risk for local recurrence.

PURPOSE: The practice policy at the University of Washington has been to employ fast neutron radiotherapy for soft tissue sarcoma lesions with prognostic features predictive for poor local control. These include gross residual disease/inoperable disease, recurrent disease, and contaminated surgical margins. Cartilaginous sarcomas have also been included in this high-risk group. This report updates and expands our previously described experience with this approach. METHODS AND MATERIALS: Eighty-nine soft tissue sarcoma lesions in 72 patients were treated with neutron radiotherapy in our department between 1984 and 1996. Six patients, each with solitary lesions, were excluded from analysis due to lack of follow-up. Seventy-three percent were treated with fast neutron radiation alone, the rest with a combination of neutrons and photons. Median neutron dose was 18.3 nGy (range 4.8-22). Forty-two patients with solitary lesions were treated with curative intent. Thirty-one patients (including 7 previously treated with neutrons) with 41 lesions were treated with the goal of local palliation. Tumors were predominantly located in the extremity and torso. Thirty of 35 (85%) of curative group patients treated postoperatively had close or positive surgical margins. Thirty-four (82%) lesions treated for palliation were unresectable. Thirty-five patients (53%) were treated at the time of recurrence. Median tumor size at initial presentation was 8.0 cm (range 0.6-29), median treated gross disease size was 5.0 cm (range 1-22), and 46/69 evaluable lesions (67%) were judged to be of intermediate to high histologic grade. Fourteen patients (21%) had chondrosarcomas. RESULTS: Median follow-up was 6 months (range 2-47) and 38 months (range 2-175) for the palliative and curative groups, respectively. Kaplan-Meier estimates were obtained for probability of local relapse-free survival (68%), distant disease-free survival (59%), cause-specific survival (68%), and overall survival (66%) at 4 years for the curatively treated group. For the palliatively treated group, estimated local relapse-free survival at 1 year was 62%. Log-rank analysis of the curative group revealed recurrent disease to be the only risk factor predictive for significantly worse local and distant disease-free survival. Intermediate-/high-grade histology was predictive for inferior overall survival. Effective clinical response was documented for 21/27 (78%) lesions treated palliatively. Ten patients (15%) experienced serious chronic radiation-related complications. All of these patients had clinical situations requiring delivery of high neutron doses and/or large radiotherapy fields. CONCLUSION: Fast neutron radiotherapy is locally effective for soft tissue and cartilaginous sarcomas having well-recognized high-risk features. Results in the palliative setting appear to be particularly encouraging, with neutrons frequently providing significant symptomatic response for gross disease, with minimal serious chronic sequelae. Fast neutron radiotherapy should be considered in patients at high risk for local recurrence in both the curative and palliative settings.

Treatment of locally advanced adenoid cystic carcinoma of the head and neck with neutron radiotherapy.

PURPOSE: To examine the efficacy of fast neutron radiotherapy for the treatment of locally advanced and/or recurrent adenoid cystic carcinoma of the head and neck and to identify prognostic variables associated with local-regional control and survival. METHODS AND MATERIALS: One hundred fifty-nine patients with nonmetastatic, previously unirradiated, locally advanced, and/or recurrent adenoid cystic carcinoma (ACC) of the head and neck region were treated with fast neutron radiotherapy during the years 1985-1997. One hundred fifty-one patients had either unresectable disease, or gross residual disease (GRD) after an attempted surgical extirpation. Eight patients had microscopic residual disease and were analyzed separately. Sixty-two percent of patients had tumors arising in minor salivary glands, 29% in major salivary glands, and 9% in other sites such as the lacrimal glands, tracheal-bronchial tree, etc. Fifty-five percent of patients were treated for postsurgical recurrent disease and 13% of patients had lymph node involvement at the time of treatment. The median duration of follow-up was 32 months (range 3-142 months). Actuarial curves for survival, cause-specific survival, local-regional control, and the development of distant metastases are presented for times out to 11 years. RESULTS: The 5-year actuarial local-regional tumor control rate for the 151 patients with GRD was 57%; the 5-year actuarial overall survival rate was 72%; and the 5-year actuarial cause-specific survival rate was 77%. Variables associated with decreased local-regional control in the patients with GRD as determined by multivariate analysis included base of skull involvement (p < 0.01) and biopsy only versus an attempted surgical resection prior to treatment (p = 0.03). Patients without these negative factors had an actuarial local-regional control rate of 80% at 5 years. Patients with microscopic residual disease (n = 8) had a 5-year actuarial local-regional control rate of 100%. Base of skull involvement (p < 0.001), lymph node metastases at the time of treatment (p < 0.01), biopsy only prior to neutron radiotherapy (p = 0.03), and recurrent tumors (p = 0.04) were found to be associated with a diminished cause-specific survival as ascertained by multivariate analysis. Patients with base of skull involvement and positive lymph nodes at presentation had an increased rate of the development of distant metastases at 5 years, (p < 0.01 and p < 0.001, respectively). No statistical difference in outcome was observed between major and minor salivary gland sites. CONCLUSIONS: Fast neutron radiotherapy is an effective treatment for locally advanced ACC of the head and neck region with acceptable toxicity. Further improvements in local-regional control are not likely to impact survival until more effective systemic agents are developed to prevent and/or treat distant metastatic disease.

Fast neutron beam radiation therapy in the United States.

Following a 30-year hiatus after Dr. Stone's work in the 1930's and 1940's, clinical trials with fast neutrons were restarted in the United States in 1972. Approximately 2500 patients have been treated with neutrons since that time. Three hundred and seven patients with squamous cell carcinomas of the head and neck were entered on an RTOG-coordinated randomized study comparing standard photon irradiation with mixed beam radiation therapy. No significant differences were noted in the local control, survival or complication rates. One hundred and sixty patients were entered on a randomized glioblastoma study. Although there were no significant differences in median survival, autopsy results showed greater tumor effect on the neutron-treated tumors. Twenty-six patients were treated for transitional cell carcinomas of the bladder with either preoperative mixed beam irradiation or mixed beam irradiation alone. Both the local control rates and survival rates compare favorably with photon radiation therapy. The future of fast neutron beam radiation therapy in the United States is discussed.

Fast neutron radiation therapy for unresectable squamous cell carcinomas of the head and neck: the results of a randomized RTOG study.

Forty patients with advanced, unresectable squamous cell carcinomas of the head and neck were entered on a prospective, randomized study comparing fast neutron radiation therapy with conventional photon radiation therapy. Twenty-six patients were randomized to neutrons, and 14 patients were randomized to photons. The randomization was purposefully unbalanced in favor of the experimental treatment. The complete response rate for the neutron-treated group of patients was 52%. The complete response rate for the photon-treated group of patients was 17%. The difference is statistically significant at the p = .04 level. The two-year survival rates for the neutron-treated group and the photon-treated group were 25 and 0%, respectively. The major complication rates were not statistically significantly different for the two groups (18% for neutrons, and 33% for photons).

Nasopharyngeal carcinoma in Saudi Arabia: a retrospective study of 166 cases treated with curative intent.

A retrospective review was performed of the medical records of 166 adult patients with biopsy-proven carcinomas of the nasopharynx treated with curative intent at King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. All patients were treated between June 1975 and December 1985 using megavoltage therapy equipment. Most patients presented with advanced nodal disease: 23 patients (13.9%) were N0, 16 patients (9.6%) were N1, 29 patients (17.5%) were N2, and 98 patients (59%) were N3. The overwhelming majority of patients had nonkeratinizing lesions (158/166). At the time of analysis, mean follow-up time was 24.2 months (range 2-108). Actuarial curves are presented for local/regional control as a function of T-stage and N-stage and for survival and time to development of distant metastases as a function of N-stage. At 4 years local/regional control was 70% for T1 lesions, 59% for T2 lesions, 30% for T3 lesions, and 35% for T4 lesions. There was little correlation between local/regional control and N-stage being about 50% at 4 years for all nodal subgroups. Only six patients exhibited an isolated first failure in the regional nodes alone, whereas 60 patients failed initially at the primary site (either alone or in conjunction with a simultaneous nodal failure). The development of distant metastases correlated to some extent with nodal disease ranging from 20% at 4 years for T1/T2 N0 patients to 70% for patients who initially presented with N3 disease. Survival data was more difficult to obtain due to cultural biases in a medically unsophisticated patient population. True survival curves are bounded by calculating actuarial curves in two ways: death as the failure endpoint and death plus lost-with-active-disease as failure endpoints. In terms of the latter curves, at 4 years "survival" ranged from 39% for patients with T1/T2 N0 lesions to 23% for patients with N3 lesions.

Neutron vs photon irradiation of inoperable salivary gland tumors: results of an RTOG-MRC Cooperative Randomized Study.

A total of 32 patients with inoperable, recurrent or unresectable malignant salivary gland tumors were entered on a randomized RTOG/MRC study comparing fast neutron radiotherapy with conventional photon radiotherapy. Twenty-five patients were entered from the United States and 7 patients were entered from Scotland. Seventeen patients were randomized to receive neutrons and 15 patients were randomized to receive photons. Sixty-one percent of the neutron-treated patients and 75% of the photon-treated patients presented with inoperable or unresectable tumors, while 39% of the neutron-treated and 25% of the photon-treated patients had recurrent disease. Twenty-five patients were study-eligible and analyzable. The minimum follow-up time is 2 years. The complete tumor clearance rates at the primary site were 85% (11/13) for neutrons and 33% (4/12) for photons following protocol treatment (p = 0.01). The complete tumor clearance rates in the cervical lymph nodes were 86% (6/7) for neutrons and 25% (1/4) for photons. The overall loco/regional complete tumor response rates were 85% and 33% for neutrons and photons respectively. The loco/regional control rates at 2 years for the 2 groups are 67% for neutrons and 17% for photons (p less than 0.005). The 2-year survival rates are 62% and 25% for neutrons and photons respectively (p = 0.10). These findings are consistent with previously published uncontrolled series.

Fast neutron radiotherapy for locally advanced prostate cancer: results of an RTOG randomized study.

Between June 1977 and April 1983, the Radiation Therapy Oncology Group (RTOG) sponsored a Phase III randomized study investigating fast neutron radiation therapy in the treatment of patients with locally advanced (Stage C and D1) adenocarcinoma of the prostate gland. Patients were randomized to receive either conventional photon radiation therapy or fast neutron irradiation used in a mixed-beam treatment schedule (neutron/photon). A total of 91 analyzable patients were entered in the study; 78 of them were treated without major protocol deviations. The two treatment groups were balanced in regard to all major prognostic variables. Actuarial curves for "overall" survival, "determinantal" survival and local/regional control are presented both for the entire group of 91 patients and the 78 patients treated within protocol guidelines. The overall local/regional tumor recurrence rate is 7% for the mixed-beam treated group of patients and is 22% for the photon (X ray) treated group of patients. The difference is statistically significant at the p = 0.05 level. For the entire group of 91 evaluable patients, the 5-year "overall" survival rate is 62% for the mixed-beam-treated group and 35% for the photon-treated group. This difference is also statistically significant (p less than 0.05). However, this statistical significance is lost when the smaller number of patients treated strictly within protocol guidelines is considered. The significance is regained (p less than 0.02) when one looks at "determinantal" survival, which uses active cancer at time of death as the failure endpoint. This study demonstrates that a regional treatment modality, in this case mixed-beam irradiation, can influence both local/regional tumor control and survival in patients with locally-advanced adenocarcinoma of the prostate gland.

Mixed neutron/photon irradiation of unresectable squamous cell carcinomas of the head and neck: the final report of a randomized cooperative trial.

Three hundred and twenty-seven patients with inoperable squamous cell carcinomas of the head and neck were entered on a randomized study comparing a mixture of neutron and photon ("mixed beam") radiation therapy with photon/electron radiation therapy. Neutron treatment was delivered with fixed-beam, physics-laboratory-based equipment. Patients with histologically proven tumors of T-stage T2, T3, or T4 and any N-stage were eligible for randomization. Primary tumor sites were limited to cancers originating in the oral cavity, oropharynx, supraglottic larynx, or hypopharynx. Patients entered on this study now have a minimum at-risk follow-up period of 6 years. Study results reveal no significant differences in overall loco-regional tumor control rates or survival. Subgroup analysis reveals significant differences based on whether or not patients presented with positive lymph nodes. Loco-regional tumor control rates for patients presenting with positive lymph nodes were 30% for mixed-beam-treated patients versus 18% for photon-treated patients (p = 0.05). Loco-regional tumor control rates for patients presenting without positive lymph nodes were 64% for photon-treated patients and 33% for mixed-beam-treated patients (p = 0.004). Control of tumor located in the nodal sites favored mixed beam over photons by a margin of 45% (49/109) to 26% (23/87) with a significance of p = 0.004. Possible explanations for these contradictory findings are discussed.

Radiation Therapy Oncology Group (RTOG) survival data on anaplastic astrocytomas of the brain: does a more aggressive form of treatment adversely impact survival?

The RTOG has sponsored several studies for malignant gliomas of the brain that have included tumors classified as either glioblastoma multiforme (GBM) or anaplastic-atypical astrocytoma (AAF) under the Nelson schema. Glioblastoma multiforme, the more aggressive histology, has done poorly under all forms of treatment having a typical median survival of 8-11 months. The less common and less aggressive anaplastic-atypical astrocytoma seems to show a survival that worsens with treatment more aggressive than standard radiotherapy. All patients in this report have had their tumors centrally reviewed by a RTOG neuropathologist and have had the diagnosis of anaplastic-atypical astrocytoma confirmed. We compare three patient groups: standard photon radiotherapy from the 60 and 70 Gy arms of RTOG 74-01/ECOG 1374 and from the 65 Gy control arm of RTOG 76-11; radiation therapy and chemotherapy from RTOG 74-01/ECOG 1374 (60 Gy + BCNU and 60 Gy + MeCCNU + DTIC) and from RTOG 79-18 (60 Gy + BCNU); and photon irradiation plus a neutron boost from RTOG 76-11 and RTOG 80-07. There are 47 analyzable cases treated with photons alone, 78 analyzable cases treated with photons + chemotherapy, and 38 analyzable cases treated with photons + neutron boost. Median survival for the three groups of patients is, respectively, 3.0 years, 2.3 years, and 1.7 years. Actuarial survival curves are presented for each subgroup of patients and then for the patient subgroups further broken down by major prognostic variables--age and Karnofsky performance status. In each "better prognostic category," the median survival decreased as the "aggressiveness" of the treatment increased. The implications of these findings for future clinical trials is discussed.

Elapsed treatment days--a critical item for radiotherapy quality control review in head and neck trials: RTOG report.

For all randomized trials since 1978, the Radiation Therapy Oncology Group has required the study chairman for radiation therapy to review the treatment given to each patient. The chairman scores the compliance of the treatment borders, total dose, fraction, and total elapsed time relative to the protocol prescription at the primary site, regional nodes, and any critical structure. The individual parameters are then considered together to derive an "overall" treatment score. For two RTOG head and neck studies in patients with moderately and very advanced carcinomas, the "overall" treatment was classified as unacceptable if the treatment at primary was scored unacceptable with respect to dose, fractionation, and field borders. However, prolonged elapsed treatment was not included. Analysis of these studies with 426 evaluable patients was performed to assess the relationship of unacceptable "overall" treatment compliance with outcome. Patients with prolonged treatment elapsed days (14 days beyond the protocol prescription) exhibited significantly poorer loco-regional control (13% vs. 27% at 3 years with p = .007) and absolute survival (13% vs. 26% at 3 years with p = .01). As a result, the criteria for unacceptable "overall" treatment were revised to include prolonged elapsed treatment days. Further multivariate analyses showed the revised criteria identified patients with significantly poorer loco-regional control and absolute survival even after adjusting for other prognostic factors.

The efficacy of radiotherapy as postoperative treatment for desmoid tumors.

PURPOSE: The purpose of this study was to determine if radiotherapy is a beneficial adjuvant treatment after desmoid tumor resection. METHODS AND MATERIALS: A retrospective analysis was performed on 54 patients who underwent surgery without prior radiation at our institution between 1982 and 1998 to remove a desmoid tumor. Thirty-five patients had adjuvant radiation therapy after surgery, and 19 patients had surgery alone without immediate postoperative radiation. Sixteen of the 35 patients who underwent immediate postoperative radiation treatment had at least one prior resection before reoperation at our institution. Recurrence was defined as radiographic increase in tumor size after treatment. Follow-up interval (mean 39 months) and duration of local control were measured from the date of surgery at our institution. Potential prognostic factors for time to tumor progression were analyzed. RESULTS: Adjuvant treatment with radiation was the only significant prognostic factor for local control. The five-year actuarial local control rate was 81% for the 35 patients who underwent radiation in addition to surgery, compared to 53% for the 19 patients who underwent surgery alone (p = 0.018). For the patients who did not receive adjuvant radiation, only younger age at the time of surgery was associated with increased risk of failure (p = 0.035). Gross or microscopic margin status and number of prior operations were not detected as prognostic for local failure. For patients who did receive postoperative radiation, only abdominal location was associated with increased risk of failure (p = 0.0097). CONCLUSION: Radiation treatment as an adjuvant to surgery improved local control over surgery alone. Multiple operations before adjuvant radiation did not decrease the probability of subsequent tumor control. Radiation should be considered as adjuvant therapy to surgery if repeated surgery for a recurrent tumor would be complicated by a significant risk of morbidity.

Neutron radiotherapy for adenoid cystic carcinoma of minor salivary glands.

PURPOSE: To examine the efficacy of fast neutron radiotherapy for the treatment of patients with locally advanced, adenoid cystic carcinoma of minor salivary glands and to identify prognostic variables associated with local control, overall survival, and cause specific survival. METHODS AND MATERIALS: Eighty-four patients having adenoid cystic carcinoma of minor salivary glands were treated with fast neutron radiotherapy during the years 1985-1994. All patients had either unresectable disease or gross disease remaining after attempted surgical extirpation. Seventeen patients had previously received conventional radiotherapy and their subsequent treatment fields and doses for neutron radiotherapy were modified for critical sites (brainstem, spinal cord, brain). Although the median doses (tumor maximum and tumor minimum) only varied by < or = 10%, treatment portals were substantially smaller in these patients because of normal tissue complication considerations. Twelve patients (13%) had distant metastases at the time of treatment and were only treated palliatively with smaller treatment portals and lower median tumor doses (< or = 80% of the doses delivered to curatively treated patients). Seventy-two patients were treated with curative intent, with nine of these having recurrent tumors after prior full-dose radiotherapy. The median duration of follow-up at the time of analysis was 31.5 months (range 3-115). Sites of disease and number of patients treated per disease site were as follows: paranasal sinus-31; oral cavity-20; oropharynx-12; nasopharynx-11; trachea-6; and other sites in the head and neck-4. RESULTS: The 5-year actuarial local-regional tumor control rate for all patients treated with curative intent was 47%. Patients without involvement of the cavernous sinus, base of skull, or nasopharynx (51 patients) had a 5-year actuarial local-regional control rate of 59%, whereas local-regional control was significantly lower (15%) for patients with tumors involving these sites (p < 0.005). In the latter cases, normal tissue injury considerations precluded delivery of the full dose to the entire tumor. Patients with no history of prior radiotherapy (63 patients) had an actuarial local control rate of 57% at 5 years compared to 18% for those (9 patients) who had been previously irradiated with conventional photons (p = 0.018). Eliminating the dose-limiting factors of prior radiation therapy and/or high risk sites of involvement, the 5-year actuarial local-regional control rate for these 46 patients was 63%, with an actuarial cause specific survival rate of 79%. Lymph node status was a predictor of distant metastasis: 57% of node positive patients developed distant metastases by 5 years compared to 15% of patients with negative nodes (p < 0.0005), and patients who had nodal involvement developed distant metastases sooner than node negative patients (p < 0.0001). The 5-year actuarial overall survival and cause specific survival for the 72 patients treated with curative intent were 59% and 64%, respectively. CONCLUSIONS: Fast neutron radiotherapy offers high local-regional control and survival rates for patients with locally advanced, unresectable adenoid cystic carcinomas of minor salivary glands. It should be considered as initial primary treatment for these patients, as well as for other patients in whom surgical extirpation would cause considerable morbidity.

Boron neutron capture therapy: a mechanism for achieving a concomitant tumor boost in fast neutron radiotherapy.

PURPOSE: For many years neutron radiation has been used to treat malignant disease both as fast neutron radiotherapy and as thermal neutron induced boron neutron capture therapy (BNCT). To date, these two approaches have been used independently of one another due to the large difference in neutron energies each employs. In this paper we discuss the potential application of BNCT to enhance the therapeutic effectiveness of a fast neutron radiotherapy beam. METHODS AND MATERIALS: Measurements are presented for the thermal neutron component that is spontaneously developed as the University of Washington fast neutron radiotherapy beam penetrates a water phantom. The biological effect of this thermalized component on cells "tagged" with boron-10 (10B) is modeled mathematically and the expected change in cell survival calculated. The model is then extended to estimate the effect this enhanced cell killing would have for increased tumor control. RESULTS: The basic predictions of the model on changes in cell survival are verified with in vitro measurements using the V-79 cell line. An additional factor of 10-100 in tumor cell killing appears achievable with currently available 10B carriers using our present neutron beam. A Poisson model is then used to estimate the change in tumor control this enhanced cell killing would produce in various clinical situations and the effect is sufficiently large so as to be clinically relevant. It is also demonstrated that the magnitude of the thermalized component can be increased by a factor of 2-3 with relatively simple changes in the beam generating conditions. CONCLUSION: BNCT may provide a means of enhancing the therapeutic effectiveness of fast neutron radiotherapy in a wide variety of clinical situations and is an area of research that should be aggressively pursued.

The influence of beam energy on the outcome of postoperative radiotherapy in head and neck cancer patients: secondary analysis of RTOG 85-03.

PURPOSE: To determine whether any difference in toxicity or efficacy occurs when head and neck cancer patients are treated postoperatively with (60)C0, 4 MV, or 6 MV photon beam. METHODS AND MATERIALS: This is a secondary analysis of the Intergroup Study 0034. Three hundred ninety-two patients were evaluable for comparison between treatment with (60)C0, 4 MV, or 6 MV photon beam. All patients had advanced but operable squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx. Patients were randomized following surgical resection to receive treatment with either postoperative irradiation alone, or postoperative irradiation plus three cycles of cisplatin and 5-fluorouracil. Patients were categorized as having either "low risk" or "high risk" treatment volumes based on whether the surgical margin was 5 mm or less, presence of extra capsular nodal extension, and/or carcinoma in situ at the surgical margins. Low-risk volumes received 50-54 Gy, and high-risk volumes were given 60 Gy. Patients were compared in regards to acute and late radiotherapy toxicities as well as overall survival and loco-regional control according to the beam energy used. RESULTS: One-hundred fifty-seven, 140, and 95 patients were treated by (60)C0, 4 MV, and 6 MV, respectively. No differences were seen in acute or late toxicity among treatment groups. Locoregional control was achieved in 75%, 79%, and 80% of patients treated with (60)C0, 4 MV, or 6 MV (p = 0.61). Patients treated with 6 MV had a higher incidence of ipsilateral neck failure as first event (13%) than patients treated by (60)C0 and 4 MV (9%). This difference was not statistically significant. CONCLUSION: No differences in outcome, acute, or late toxicity were discernible in patients with advanced head and neck cancer treated with (60)C0, 4 MV, or 6 MV. This result should be interpreted with caution as increased incidence, albeit nonsignificant, of ipsilateral neck recurrence was observed in patients treated with 6 MV and the power of the study to detect a statistically significant difference is small.

Fast neutron irradiation of metastatic cervical adenopathy: the results of a randomized RTOG study.

Between 1977 and 1982, 199 evaluable patients with measurable cervical adenopathy were entered on a prospective, randomized RTOG study evaluating the use of fast neutrons in treatment of advanced, inoperable squamous cell carcinomas of the head and neck region. One hundred-eleven patients were randomized to receive mixed beam radiation therapy, and 88 were randomized to the photon control treatment. The complete response rates were 86% for mixed beam vs 75% for photons for Stage N1 nodes, 62% for mixed beam vs 48% for photons for Stage N2 nodes, and 63% for mixed beam vs 53% for photons for N3 nodes. The percents of patients remaining free of their adenopathy for two years were 78% for mixed beam vs 55% for photons for Stage N1 nodes, 39% for both mixed beam and photons for N2 nodes and 24% for mixed beam vs 13% for photons for N3 nodes. The median disease-free status was 20.3 months for mixed beam treated patients and 6.4 months for photon-treated patients. Patients who had clearance of cervical adenopathy survived significantly longer than those who did not.