Accurate Three-Dimensional Thermal Dosimetry and Assessment of Physiologic Response Are Essential for Optimizing Thermoradiotherapy.

Numerous randomized trials have revealed that hyperthermia (HT) + radiotherapy or chemotherapy improves local tumor control, progression free and overall survival vs. radiotherapy or chemotherapy alone. Despite these successes, however, some individuals fail combination therapy; not every patient will obtain maximal benefit from HT. There are many potential reasons for failure. In this paper, we focus on how HT influences tumor hypoxia, since hypoxia negatively influences radiotherapy and chemotherapy response as well as immune surveillance. Pre-clinically, it is well established that reoxygenation of tumors in response to HT is related to the time and temperature of exposure. In most pre-clinical studies, reoxygenation occurs only during or shortly after a HT treatment. If this were the case clinically, then it would be challenging to take advantage of HT induced reoxygenation. An important question, therefore, is whether HT induced reoxygenation occurs in the clinic that is of radiobiological significance. In this review, we will discuss the influence of thermal history on reoxygenation in both human and canine cancers treated with thermoradiotherapy. Results of several clinical series show that reoxygenation is observed and persists for 24-48 h after HT. Further, reoxygenation is associated with treatment outcome in thermoradiotherapy trials as assessed by: (1) a doubling of pathologic complete response (pCR) in human soft tissue sarcomas, (2) a 14 mmHg increase in pO2 of locally advanced breast cancers achieving a clinical response vs. a 9 mmHg decrease in pO2 of locally advanced breast cancers that did not respond and (3) a significant correlation between extent of reoxygenation (as assessed by pO2 probes and hypoxia marker drug immunohistochemistry) and duration of local tumor control in canine soft tissue sarcomas. The persistence of reoxygenation out to 24-48 h post HT is distinctly different from most reported rodent studies. In these clinical series, comparison of thermal data with physiologic response shows that within the same tumor, temperatures at the higher end of the temperature distribution likely kill cells, resulting in reduced oxygen consumption rate, while lower temperatures in the same tumor improve perfusion. However, reoxygenation does not occur in all subjects, leading to significant uncertainty about the thermal-physiologic relationship. This uncertainty stems from limited knowledge about the spatiotemporal characteristics of temperature and physiologic response. We conclude with recommendations for future research with emphasis on retrieving co-registered thermal and physiologic data before and after HT in order to begin to unravel complex thermophysiologic interactions that appear to occur with thermoradiotherapy.

Hyperthermia combined with radiation therapy for superficial breast cancer and chest wall recurrence: a review of the randomised data.

Hyperthermia has long been used in combination with radiation for the treatment of superficial malignancies, in part due to its radiosensitising capabilities. Patients who suffer superficial recurrences of breast cancer, be it in their chest wall following mastectomy, or in their breast after breast conservation, typically have poor clinical outcomes. They often develop distant metastatic disease, but one must not overlook the problems associated with an uncontrolled local failure. Morbidity is enormous, and can significantly impair quality of life. There is no accepted standard of care in treating superficial recurrences of breast cancer, particularly in patients that have previously been irradiated. There is a substantial literature regarding the combined use of hyperthermia and radiotherapy for these superficial recurrences. Most of it is retrospective in nature, but there are several larger phase III randomised trials that show an improved rate of clinical complete response in patients treated with both modalities. In this review article, we will highlight the important prospective data that has been published regarding the combined use of hyperthermia and radiation.

Hyperthermia for locally advanced breast cancer.

Hyperthermia (HT) has a proven benefit for treating superficial malignancies, particularly chest wall recurrences of breast cancer. There has been less research utilising HT in patients with locally advanced breast cancer (LABC), but available data are promising. HT has been combined with chemotherapy and/or radiotherapy in the neoadjuvant, definitive and adjuvant setting, albeit in series with small numbers of patients. There is only one phase III trial that examines hyperthermia in LABC, also with relatively small numbers of patients. The goal of this review is to highlight important research utilising HT in patients with LABC as well as to suggest future directions for its use.

Equivalent uniform dose, D(90), and V(100) correlation with biochemical control after low-dose-rate prostate brachytherapy for clinically low-risk prostate cancer.

PURPOSE: To assess the correlation of postimplant dosimetric quantifiers with biochemical control of prostate cancer after low-dose-rate brachytherapy. MATERIALS AND METHODS: Generalized equivalent uniform dose (EUD), dose in Gy to 90% of the prostate gland (D(90)), and percentage of the prostate receiving 100% of the prescribed dose (V(100)) were calculated from the postimplant dose-volume histogram (DVH) for 140 patients undergoing low-dose-rate prostate brachytherapy (LDRPB) monotherapy from 1997 to 2003 at Duke University and the Durham VA Medical Center. Biochemical recurrence was defined according to the American Society for Therapeutic Radiology and Oncology consensus definition. RESULTS: Median followup after LDRPB was 50 months. There was a 7% biochemical recurrence rate (10/140) at last clinical followup. The median EUD was 167 Gy (range, 41-245). The median D(90) was 139 Gy (range, 45-203). The median V(100) was 88% (range, 44-100). The overall 5-year biochemical recurrence-free survival (bRFS) was 94.2%. The 5-year bRFS was 100% for EUD> or =167 Gy and 89.4% for EUD <167 Gy (p=0.008); 100% for D(90) > or =140 Gy and 90.4% for D(90) <140 Gy (p=0.020); 100% for V(100) > or =88%; and 90.3% for V(100) <88% (p=0.017). There was no statistically significant correlation between any of these factors and overall survival. CONCLUSIONS: In our series of 140 patients with low-risk prostate cancer treated with LDRPB alone, we observed a statistically significant correlation between EUD, D(90), and V(100) and bRFS. The generalized EUD, a calculated value that incorporates the entire prostate DVH, appears to be at least as well correlated with bRFS as D(90) or V(100), and may more completely represent the totality of the dose distribution.

Randomized trial of hyperthermia and radiation for superficial tumors.

PURPOSE: Randomized clinical trials have demonstrated hyperthermia (HT) enhances radiation response. These trials, however, generally lacked rigorous thermal dose prescription and administration. We report the final results of a prospective randomized trial of superficial tumors (

Predictors of severe gastrointestinal toxicity after external beam radiotherapy and interstitial brachytherapy for advanced or recurrent gynecologic malignancies.

PURPOSE: The aim of this retrospective review of patients with gynecologic malignancies treated with external beam radiotherapy (EBRT) and interstitial brachytherapy was to determine the rate of Grade > or =2 rectovaginal fistula and Grade > or =4 small bowel obstruction as defined by the National Cancer Institute Common Toxicity Criteria for Adverse Events, version 3.0. METHODS AND MATERIALS: Thirty-six patients with primary and recurrent gynecologic cancers were treated with EBRT and interstitial brachytherapy. Median doses to tumor, bladder, and rectum were 75 Gy, 61 Gy, and 61 Gy, respectively. A univariate analysis was performed to identify variables that correlated with toxicity. RESULTS: At median follow-up of 19 months, the 3-year risk of small bowel obstruction was 6%. Those patients with prior abdomino-pelvic surgery who received EBRT with antero-posterior fields had higher rates of obstruction than patients without prior abdomino-pelvic surgery or those who received EBRT with four fields (50% vs. 0%, p < 0.0001). The 3-year risk of rectovaginal fistula was 18% and was significantly higher in patients who received >76 Gy to the rectum compared with those who received < or =76 Gy (100% vs. 7%, p = 0.009). CONCLUSIONS: Patients treated with EBRT and interstitial brachytherapy after abdomino-pelvic surgery should receive EBRT with four fields and the cumulative rectal dose should be < or =76 Gy.

Oxygen and Perfusion Kinetics in Response to Fractionated Radiation Therapy in FaDu Head and Neck Cancer Xenografts Are Related to Treatment Outcome.

PURPOSE: To test whether oxygenation kinetics correlate with the likelihood for local tumor control after fractionated radiation therapy. METHODS AND MATERIALS: We used diffuse reflectance spectroscopy to noninvasively measure tumor vascular oxygenation and total hemoglobin concentration associated with radiation therapy of 5 daily fractions (7.5, 9, or 13.5 Gy/d) in FaDu xenografts. Spectroscopy measurements were obtained immediately before each daily radiation fraction and during the week after radiation therapy. Oxygen saturation and total hemoglobin concentration were computed using an inverse Monte Carlo model. RESULTS: First, oxygenation kinetics during and after radiation therapy, but before tumor volumes changed, were associated with local tumor control. Locally controlled tumors exhibited significantly faster increases in oxygenation after radiation therapy (days 12-15) compared with tumors that recurred locally. Second, within the group of tumors that recurred, faster increases in oxygenation during radiation therapy (day 3-5 interval) were correlated with earlier recurrence times. An area of 0.74 under the receiver operating characteristic curve was achieved when classifying the local control tumors from all irradiated tumors using the oxygen kinetics with a logistic regression model. Third, the rate of increase in oxygenation was radiation dose dependent. Radiation doses ≤9.5 Gy/d did not initiate an increase in oxygenation, whereas 13.5 Gy/d triggered significant increases in oxygenation during and after radiation therapy. CONCLUSIONS: Additional confirmation is required in other tumor models, but these results suggest that monitoring tumor oxygenation kinetics could aid in the prediction of local tumor control after radiation therapy.

External beam radiation therapy in the treatment of patients with extranodal stage IA non-Hodgkin's lymphoma.

The purpose of this report was to study the results of external beam radiotherapy for patients with extranodal stage IA non-Hodgkin's lymphoma (NHL). A retrospective review was carried out on 27 patients seen between 1984 and 1998 with stage IA NHL of extranodal sites, and followed up for a minimum of 1 year. Sites involved included eye/orbit (seven), parotid (five), breast (four), Waldeyer ring (four), thyroid (three), other head and neck (two), stomach (one), and prostate (one). All patients had biopsy-proven disease and underwent staging workup to rule out other sites of disease. Histologic analysis revealed 16 patients with low-grade NHL, 9 with intermediate-grade, and 2 with high-grade. Ten patients received chemotherapy before radiation therapy, and eight of them had a complete response. The remaining 17 patients were treated with external beam radiation therapy alone. Radiation was directed to the involved field at 1.8 Gy to 2.0 Gy per fraction to a median dose of 40 Gy (range: 20-50.4 Gy). The median patient age was 71 years (range: 39-85 years); 55% were female, and 45% were male. A complete response was attained in all 27 patients after radiation therapy. There were five failures (all in uninvolved distant sites), and two deaths during the follow-up. Median disease free survival (DFS) and overall survival (OS) have not been reached. The 5-year DFS and OS are 85% and 94%, respectively. Older age at presentation showed a trend toward worse outcome (p = 0.07), but because of the relatively few events, other factors (radiation dose, grade of disease, sex, or the use of chemotherapy) showed no statistical differences among the patients. External beam radiation therapy is a highly effective treatment for stage IA NHL found in extranodal sites.

Biologically effective dose (BED) correlation with biochemical control after low-dose rate prostate brachytherapy for clinically low-risk prostate cancer.

PURPOSE: To assess the correlation of postimplant dosimetric quantifiers with biochemical control of prostate cancer after low-dose rate brachytherapy. METHODS AND MATERIALS: The biologically effective dose (BED), dose in Gray (Gy) to 90% of prostate (D(90)), and percent volume of the prostate receiving 100% of the prescription dose (V(100)) were calculated from the postimplant dose-volume histogram for 140 patients undergoing low-dose rate prostate brachytherapy from 1997 to 2003 at Durham Regional Hospital and the Durham VA Medical Center (Durham, NC). RESULTS: The median follow-up was 50 months. There was a 7% biochemical failure rate (10 of 140), and 91% of patients (127 of 140) were alive at last clinical follow-up. The median BED was 148 Gy (range, 46-218 Gy). The median D(90) was 139 Gy (range, 45-203 Gy). The median V(100) was 85% (range, 44-100%). The overall 5-year biochemical relapse-free survival (bRFS) rate was 90.1%. On univariate Cox proportional hazards modeling, no pretreatment characteristic (Gleason score sum, age, baseline prostate-specific antigen, or clinical stage) was predictive of bRFS. The BED, D(90), and V(100) were all highly correlated (Pearson coefficients >92%), and all were strongly correlated with bRFS. Using the Youden method, we identified the following cut points for predicting freedom from biochemical failure: D(90) >or= 110 Gy, V(100) >or= 74%, and BED >or= 115 Gy. None of the covariates significantly predicted overall survival. CONCLUSIONS: We observed significant correlation between BED, D(90), and V(100) with bRFS. The BED is at least as predictive of bRFS as D(90) or V(100). Dosimetric quantifiers that account for heterogeneity in tumor location and dose distribution, tumor repopulation, and survival probability of tumor clonogens should be investigated.

Dosimetric and radiobiologic comparison of 3D conformal versus intensity modulated planning techniques for prostate bed radiotherapy.

Adjuvant radiotherapy for locally advanced prostate cancer improves biochemical and clinical disease-free survival. While comparisons in intact prostate cancer show a benefit for intensity modulated radiation therapy (IMRT) over 3D conformal planning, this has not been studied for post-prostatectomy radiotherapy (RT). This study compares normal tissue and target dosimetry and radiobiological modeling of IMRT vs. 3D conformal planning in the postoperative setting. 3D conformal plans were designed for 15 patients who had been treated with IMRT planning for salvage post-prostatectomy RT. The same computed tomography (CT) and target/normal structure contours, as well as prescription dose, was used for both IMRT and 3D plans. Normal tissue complication probabilities (NTCPs) were calculated based on the dose given to the bladder and rectum by both plans. Dose-volume histogram and NTCP data were compared by paired t-test. Bladder and rectal sparing were improved with IMRT planning compared to 3D conformal planning. The volume of the bladder receiving at least 75% (V75) and 50% (V50) of the dose was significantly reduced by 28% and 17%, respectively (p = 0.002 and 0.037). Rectal dose was similarly reduced, V75 by 33% and V50 by 17% (p = 0.001 and 0.004). While there was no difference in the volume of rectum receiving at least 65 Gy (V65), IMRT planning significant reduced the volume receiving 40 Gy or more (V40, p = 0.009). Bladder V40 and V65 were not significantly different between planning modalities. Despite these dosimetric differences, there was no significant difference in the NTCP for either bladder or rectal injury. IMRT planning reduces the volume of bladder and rectum receiving high doses during post-prostatectomy RT. Because of relatively low doses given to the bladder and rectum, there was no statistically significant improvement in NTCP between the 3D conformal and IMRT plans.

Intra-peritoneal cisplatin and whole abdomen hyperthermia for relapsed ovarian carcinoma.

The study was designed to determine the maximum tolerated dose (MTD) of IP cisplatin [CDDP] combined with intravenous thiosulphate and concurrent whole abdomen hyperthermia for advanced, recurrent or progressive ovarian carcinoma. Between September 1991 and November 1998, 41 patients with advanced epithelial ovarian cancer received escalating doses of IP (IP) cisplatin (six cycles given every 3-4 weeks) and whole abdomen hyperthermia with intravenous thiosulphate as second line treatment. Whole abdomen hyperthermia was administrated using a BSD-2000 annular phased array system. Forty-one patients were enrolled in the phase I/II portions of the study. Forty-four per cent (18/41) had undergone sub-optimal cytoreductive surgery and 15% (6/41) had been optimally debulked of their disease. Ninety per cent (37/41) had platinum-resistant disease and 10% (4/41) had platinum-sensitive disease. No DLTs occurred in the phase I testing and the recommended dose for this combination schedule was 180 mg m-2 of IP cisplatin with thiosulphate and whole abdomen hyperthermia. The overall response rate was 44% (10 CR, 8 PR) and the median survival for all patients from protocol entry was 30 months (range 2-107 months). Median duration and survival of those achieving a pathologic CR was 14 months (range 2-27 months) and 35 months (range 14-71 months, 95% CI 16-54 months), respectively. Salvage platinum based IP cisplatin with hyperthermia did achieve pathologic CR in selected patients and was well tolerated. These promising results suggest a role for the use of adjuvant whole abdomen hyperthermia as a means of augmenting chemosensitization.