Evaluation of the ESMO-Magnitude of Clinical Benefit Scale version 1.1 (ESMO-MCBS v1.1) for adjuvant radiotherapy in breast cancer.

BACKGROUND: The European Society of Medical Oncology (ESMO) has suggested using the ESMO-Magnitude of Clinical Benefit Scale (MCBS) to grade the magnitude of clinical benefit of cancer therapies. This approach has not been applied to radiation therapy (RT) yet. We applied the ESMO-MCBS to experiences describing the use of RT to assess (1) the 'scoreability' of the data, (2) evaluate the reasonableness of the grades for clinical benefit and (3) identify potential shortcomings in the current version of the ESMO-MCBS in its applicability to RT. MATERIALS AND METHODS: We applied the ESMO-MCBS v1.1 to a selection of studies in radiotherapy that had been identified as references in the development of American Society for Radiation Oncology (ASTRO) evidence-based guidelines on whole breast radiation. Of the 112 cited references, we identified a subset of 16 studies that are amenable to grading using the ESMO-MCBS. RESULTS: Of the 16 studies reviewed, 3/16 were scoreable with the ESMO tool. Six of 16 studies could not be scored because of shortcomings in the ESMO-MCBS v1.1: (1) in 'non-inferiority studies', there is no credit for improved patient convenience, reduced patient burden or improved cosmesis; (2) in 'superiority studies' evaluating local control as a primary endpoint, there is no credit for the clinical benefit such as reduced need for further interventions. In 7/16 studies, methodological deficiencies in the conduct and reporting were identified. CONCLUSIONS: This study represents a first step in determining the utility of the ESMO-MCBS in the evaluation of clinical benefit in radiotherapy. Important shortcomings were identified that would need to be addressed in developing a version of the ESMO-MCBS that can be robustly applied to radiotherapy treatments. Optimization of the ESMO-MCBS instrument will proceed to enable assessment of value in radiotherapy.

High-dose chemotherapy and autologous bone marrow support as consolidation after standard-dose adjuvant therapy for high-risk primary breast cancer.

PURPOSE: We studied high-dose cyclophosphamide, cisplatin, and carmustine (CPA/cDDP/BCNU) with autologous bone marrow support (ABMS) as consolidation after standard-dose adjuvant chemotherapy treatment of primary breast cancer involving 10 or more axillary lymph nodes. PATIENTS AND METHODS: One hundred two women with stage IIA, IIB, IIIA, or IIIB breast cancer involving 10 or more lymph nodes at surgery were registered; 85 were eligible, treated, and assessable. Patients were treated with four cycles of standard-dose cyclophosphamide, doxorubicin, and fluorouracil (CAF), followed by high-dose CPA/cDDP/BCNU with ABMS. RESULTS: Actuarial event-free survival for the study patients at a median follow-up of 2.5 years is 72% (95% confidence interval, 56% to 82%). Comparison to three historical or concurrent Cancer and Leukemia Group B (CALGB) adjuvant chemotherapy trials selected for similar patients showed event-free survival at 2.5 years to be between 38% and 52%. Therapy-related mortality was 12%; pulmonary toxicity of variable severity occurred in 31% of patients. Quality-of-life evaluations indicate that patients are functioning well without major impairments. CONCLUSION: High-dose consolidation with CPA/cDDP/BCNU and ABMS after standard-dose CAF results in a decreased frequency of relapse in patients with high-risk primary breast cancer compared with historical series at the median follow-up of 2.5 years. Evaluation in a prospective, randomized trial is warranted and currently underway.

Using plasma transforming growth factor beta-1 during radiotherapy to select patients for dose escalation.

PURPOSE: The ability to prescribe treatment based on relative risks for normal tissue injury has important implications for oncologists. In non-small-cell lung cancer, increasing the dose of radiation may improve local control and survival. Changes in plasma transforming growth factor beta (TGFbeta) levels during radiotherapy (RT) may identify patients at low risk for complications in whom higher doses of radiation could be safely delivered. PATIENT AND METHODS: Patients with locally advanced or medically inoperable non-small-cell lung cancer received three-dimensional conformal RT to the primary tumor and radiographically involved nodes to a dose of 73.6 Gy (1.6 Gy twice daily). If the plasma TGFbeta level was normal after 73.6 Gy, additional twice daily RT was delivered to successively higher total doses. The maximum-tolerated dose was defined as the highest radiation dose at which < or = one grade 4 (life-threatening) late toxicity and < or = two grade 3 to 4 (severe life-threatening) late toxicities occurred. RESULTS: Thirty-eight patients were enrolled. Median follow-up was 16 months. Twenty-four patients were not eligible for radiation dose escalation beyond 73.6 Gy because of persistently abnormal TGFbeta levels. Fourteen patients whose TGFbeta levels were normal after 73.6 Gy were escalated to 80 Gy (n = 8) and 86.4 Gy (n = 6). In the 86.4-Gy group, dose-limiting toxicity was reached because there were two (33%) grade 3 late toxicities. CONCLUSION: It is feasible to use plasma TGFbeta levels to select patients for RT dose escalation for non-small-cell lung cancer. The maximum-tolerated dose using this approach is 86.4 Gy.

Can we predict radiation-induced changes in pulmonary function based on the sum of predicted regional dysfunction?

PURPOSE: To determine whether changes in whole-lung pulmonary function test (PFT) values are related to the sum of predicted radiation therapy (RT)-induced changes in regional lung perfusion. PATIENTS AND METHODS: Between 1991 and 1998, 96 patients (61% with lung cancer) who were receiving incidental partial lung irradiation were studied prospectively. The patients were assessed with pre- and post-RT PFTs (forced expiratory volume in one second [FEV1] and diffusion capacity for carbon monoxide [DLCO]) for at least a 6-month follow-up period, and patients were excluded if it was determined that intrathoracic recurrence had an impact on lung function. The maximal declines in PFT values were noted. A dose-response model based on RT-induced reduction in regional perfusion (function) was used to predict regional dysfunction. The predicted decline in pulmonary function was calculated as the weighted sum of the predicted regional injuries: equation [see text] where Vd is the volume of lung irradiated to dose d, and Rd is the reduction in regional perfusion anticipated at dose d. RESULTS: The relationship between the predicted and measured reduction in PFT values was significant for uncorrected DLCO (P = .005) and borderline significant for DLCO (P = .06) and FEV1 (P = .08). However, the correlation coefficients were small (range,.18 to.30). In patients with lung cancer, the correlation coefficients improved as the number of follow-up evaluations increased (range,.43 to.60), especially when patients with hypoperfusion in the lung adjacent to a central mediastinal/hilar thoracic mass were excluded (range,.59 to.91). CONCLUSION: The sum of predicted RT-induced changes in regional perfusion is related to RT-induced changes in pulmonary function. In many patients, however, the percentage of variation explained is small, which renders accurate predictions difficult.

73.6 Gy and beyond: hyperfractionated, accelerated radiotherapy for non-small-cell lung cancer.

PURPOSE: To assess results with twice-daily high-dose radiotherapy (RT) for non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Between 1991 and 1998, 94 patients with unresectable NSCLC were prescribed > or = 73.6 Gy via accelerated fractionation. Fifty were on a phase II protocol (P group); 44 were similarly treated off-protocol (NP group). The clinical target volume received 45 Gy at 1.25 Gy bid (6-hour interval). The gross target volume received 1.6 Gy bid to 73.6 to 80 Gy over 4.5 to 5 weeks using a concurrent boost technique. Overall survival (OS) and local progression-free survival (LPFS) were calculated by the Kaplan-Meier method. Median follow-up durations for surviving P and NP patients were 67 and 16 months, respectively. RESULTS: Total doses received were > or = 72 Gy in 97% of patients. The median OS by stage was 34, 13, and 12 months for stages I/II, IIIa, and IIIb, respectively. LPFS was significantly longer for patients with T1 lesions (median, 43 months) versus T2-4 (median, 7 to 10 months; P =.01). Results were similar in the P and NP groups. Acute grade > or = 3 toxicity included esophagus (14 patients; 15%), lung (three patients; 3% [one grade 5]), and skin (four patients; 4%). Grade > or = 3 late toxicity in 86 assessable patients included esophagus (three patients; 3%), lung (15 patients; 17% [three grade 5]), skin (five patients; 6%), heart (two patients; 2%), and nerve (one patient; 1%). CONCLUSION: This regimen yielded favorable survival results, particularly for T1 lesions. Acute grade > or = 3 toxicity seems greater than for conventional RT, though most patients recovered. Late grade > or = 3 pulmonary toxicity occurred in 17%. Because of continued locoregional recurrences, we are currently using doses > or = 86 Gy.

Impact of consolidation radiotherapy in patients with advanced breast cancer treated with high-dose chemotherapy and autologous bone marrow rescue.

PURPOSE: To examine the impact of consolidation radiotherapy (RT) after high-dose chemotherapy with autologous bone marrow rescue (HDC) in patients with advanced breast cancer. PATIENTS AND METHODS: Between 1988 and 1994,425 patients with metastatic or recurrent breast cancer received doxorubicin, fluorouracil, and methotrexate (AFM) induction chemotherapy in a single-institution prospective trial. One hundred patients who achieved a complete response were randomized to receive HDC (cyclophosphamide, cisplatin, carmustine), with autologous bone marrow rescue immediately after AFM, or to observation, with HDC to be administered at next relapse. Seventy-four of the 100 became eligible for RT; 53 received consolidation RT (HDC RT+ and 21 did not (HDC RT-). The assignment of RT was not randomized. The RT+ and RT- groups were similar with regard to number of involved sites, the fraction of patients with only local-regional disease, age, and interval since initial diagnosis. Local control at previously involved sites and distant sites was assessed with extensive radiologic and clinical evaluations at the time of first failure or most recent follow-up. The impact of RT on failure patterns, event-free survival, and overall survival was evaluated. RESULTS: Sites of first failure were located exclusively at previously involved sites in 28% of RT+ patients versus 62% of RT- patients (P < .01). Event-free survival at 4 years was 31% and 21% in the RT+ and RT-groups, respectively (P = .02). Overall survival at 4 years was 30% and 16% in the RT+ and RT- groups, respectively (P = .20). CONCLUSION: Patients with advanced breast cancer who were treated with HDC without RT failed predominantly at the initial sites of disease. The addition of RT appeared to reduce the failure rate at initial disease sites and may improve event-free and overall survival. Our observations await verification in a trial in which assignment to RT is randomized.

The impact of pre-radiotherapy surgery on radiation-induced lung injury.

AIMS: The use of postoperative radiation therapy (PORT) is predicated by an assessment of the potential benefits and risks, including radiation-induced lung injury. In this study, the risk of radiation-induced lung injury is assessed in patients who received PORT, and compared with a group of patients who received radiation without prior surgery, to determine if surgery increases the risk of radiation pneumonitis. MATERIALS AND METHODS: From 1991 to 2003, 251 patients with lung cancer were enrolled into a prospective study to assess radiation-induced lung injury. All patients received three-dimensional-planned, external-beam radiotherapy. One hundred and seventy-seven patients with over 6-months follow-up were eligible. For the current analysis, 49 patients (28%) had surgical intervention before radiotherapy. The rates of Grade 2 symptomatic pneumonitis in subgroups, based on the type of pre-radiation surgery, were computed and compared using Fisher's Exact Test. To consider the confounding factor of irradiated lung volume, patient subgroups were further defined on the basis of the mean lung dose. RESULTS: Surgical procedures included pneumonectomy (n=9), lobectomy (n=16), wedge resection (n=8) and exploration without resection (n=16). Radiation-induced lung injury occurred in 33 out of 177 (19%) patients, including 18% of the surgical group and 19% of the non-surgical group. Additionally, no statistically significant difference was found in the rate of radiation-induced lung injury based on the extent of resection. CONCLUSIONS: The incidence of pneumonitis is similar in the surgical and non-surgical groups. Thus, PORT may be safely given to selected patients after surgical exploration or resection.

The physical parameters and molecular events associated with radiation-induced lung toxicity.

Radiation therapy (RT) is frequently used to treat patients with tumors in and around the thorax. Clinical radiation pneumonitis is a common side effect, occurring in 5% to 20% of patients. Efforts to identify patients at risk for pneumonitis have focused on physical factors, such as dose and volume. Recently, the underlying molecular biological mechanisms behind RT-induced lung injury have come under study. Improved knowledge of the molecular events associated with RT-induced lung injury may translate into a better ability to individualized therapy. This review discusses our current understanding of the physical and molecular factors contributing to RT-induced pulmonary injury.

Functional imaging of normal tissues with nuclear medicine: applications in radiotherapy.

Functional imaging techniques are gaining significant interest from radiation oncologists. Many now claim the need for physical and physiological information during both treatment planning and in the study of normal tissue injury. Toward this goal, the nuclear medicine functional imaging modalities, single-photon emission computed tomography and positron-emission computed tomography, have been used. This article reviews the studies performed in radiotherapy that used these modalities, and attempts to stimulate further interest in this topic.

Postmastectomy radiotherapy: toxicities and techniques to reduce them.

The role of locoregional radiation therapy after mastectomy is controversial. It reduces the risk of tumor relapse, improves breast cancer-specific survival and possibly overall survival, but has potential morbidity. This article reviews the technical aspects of postmastectomy radiation therapy and its associations with treatment-related morbidity. We consider common problems that arise in the technical setup of radiation fields. Adverse effects of postmastectomy radiation therapy may be reduced or prevented by careful radiation treatment planning.

Radiotherapy for prostate cancer: should the seminal vesicles be considered target?

During radiotherapy for prostate cancer, the ability to predict occult seminal vesicle invasion is important since irradiation of the entire seminal vesicles necessitates enlarging the radiation fields beyond what is usually used to irradiate the prostate gland alone. We analyzed the records of 302 patients with clinical Stage T1 or T2 adenocarcinoma of the prostate treated with radical surgery at Duke University Medical Center between 1970 and 1983. Univariate and multivariate analyses were used to examine the relationship between the risk of occult seminal vesicle involvement (defined herein as histologic involvement of the seminal vesicles not detected by physical or radiologic examination) and the following factors: histologic grade, age, clinical stage, and preoperative acid phosphatase. Among 249 patients with complete information, increasing histologic grade (p < 0.001) and clinical stage (p < 0.04) were found to be the strongest predictors of occult seminal vesicle invasion. Conversely, seminal vesicle invasion was very unusual in well-differentiated T1-T2 tumors (6%). This low risk group represented 28% (70/249) of this patient population. There appears to be a substantial subset of patients with well differentiated T1 or T2 tumors who are at very low risk for occult seminal vesicle involvement and in whom the seminal vesicles can be excluded from the target volume. The reduction in target volume may reduce normal tissue reactions, facilitate dose escalation, and possibly increase local control rates.

Selection of coplanar or noncoplanar beams using three-dimensional optimization based on maximum beam separation and minimized nontarget irradiation.

PURPOSE: The design of an appropriate set of multiple fixed fields to achieve a steep dose gradient at the tumor edge, with minimal normal tissue exposure, is a very difficult problem, since a virtually infinite number of possible beam orientations exists. In practice we have selected beams in an iterative and often time-consuming process. This work proposes an optimization method, based on geometric and dose elements, to effectively arrive at a set of beam orientations. METHODS AND MATERIALS: Beams are selected by minimizing a goal function including an angle function (beam separation for steep dose gradient at target edge) and a length function (related to normal tissue dose volume histogram). The relative importance of these two factors may be adjusted depending on the clinic situation. The model is flexible and can include case specific practical anatomic and physical considerations. RESULTS: In extremely simple situations, the goal function yields results consistent with well-known analytical solutions. When applied to more complex clinical situations, it provides clinically reasonable solutions similar to those empirically developed by the clinician. The optimization process takes approximately 25 min on a UNIX workstation. CONCLUSION: The optimization scheme provides a practical means for rapidly designing multiple field coplanar or noncoplanar treatments. It overcomes limitations in human three-dimensional visualization such as trying to visualize beam directions and keeping track of the hinge angle between beams while accounting for anatomic/machine constraints. In practice, it has been used as a starting point for physicians to make modifications, based on their clinical judgment.

Accelerated repopulation: friend or foe? Exploiting changes in tumor growth characteristics to improve the "efficiency" of radiotherapy.

Accelerated repopulation (rapid multiplication of surviving clonogens) during a course of radiation therapy may contribute to local failure. This possibility has prompted accelerated treatment programs in an attempt to reduce overall treatment time, thereby minimizing the impact of repopulation. However, accelerated dose delivery at the start of treatment may not be advantageous since many of the tumor cells are likely to be hypoxic (non-cycling cells) and therefore relatively radioresistant. Conversely, accelerated treatment is likely to be most helpful later in treatment when the tumor has shrunk and accelerated repopulation of clonogens is a dominant factor. A series of calculations are presented that stimulate changes in tumor size, clonogen number, clonogen repopulation, and growth fraction during a course of fractionated radiation treatments for an idealized 2 cm diameter spherical tumor. The efficiency of each fraction of radiation is calculated for different radiation fractionation schemes. Efficiency is defined as the change in Log clonogen number (reflecting cell death due to radiation minus repopulation that has occurred during the interval between fractions) per Gy. These calculations suggest that relatively low total daily doses (approximately 2 Gy) are most efficient early in treatment. Higher daily doses are less efficient since the growth fraction is relatively low at the start of treatment. Later in treatment, as the tumor shrinks and the growth fraction approaches 1, accelerated repopulation becomes a major problem and higher total daily doses are more efficient. At this point, accelerated hyperfractionation should be used to increase the daily dose without exposing normal tissues to high fraction sizes. Thus, changes in tumor growth characteristics are exploited and dose delivery can be optimized by escalating daily irradiation doses during a course of fractionated irradiation. Strict interpretation of these conclusions must be tempered by the various assumptions and uncertainties included in this model. The concept of efficiency is useful since it reflects the competing effects of clonogen repopulation and radiation induced clonogen sterilization.

The lack of impact of pelvic irradiation on small bowel mobility: implications for radiotherapy treatment planning.

PURPOSE: Small bowel contrast is frequently used during simulation for patients undergoing pelvic radiotherapy to assist in the design of blocks that exclude small bowel from the radiation field. In many instances, a large field is treated to 45 gray (Gy), followed by a field reduction to exclude the small bowel. This prospective study was designed to assess whether the position and mobility of the small bowel changed after the initial 45 Gy, thereby determining whether a special small bowel series done at initial simulation is applicable at the time of field reduction. METHODS AND MATERIALS: Twelve patients undergoing pelvic irradiation were given small bowel contrast for their initial simulation. Radiographs were taken with the bladder empty and the bladder full. The location of the small bowel and its displacement with bladder distention was measured. This entire procedure was repeated prior to field reduction (after 39.6-46.0 Gy). RESULTS: There was no demonstrable alteration in small bowel mobility after 39.6-46.0 Gy. The approximate position of the small bowel relative to bony landmarks was unchanged. CONCLUSION: The position and mobility of the small bowel appears not to be affected by 39.6-46.0 Gy of pelvic radiotherapy. Therefore, it is reasonable to design reduced pelvic fields to exclude the small bowel based on special small bowel series done at initial treatment simulation.

A simple device to position large/flaccid breasts during tangential breast irradiation.

PURPOSE: It is technically difficult to irradiate large pendulous or flaccid breasts with tangential photon fields because they often lie very high or lateral on the chestwall. We, therefore, designed a device to reposition the breast on the chestwall to facilitate treatment. METHODS AND MATERIALS: A device to aid in repositioning the breast on the chestwall has been designed. The device consists of a reinforced polyvinylchloride tube formed into a ring that is placed around the breast. A strap around the patient's chest holds the ring in place. The breast tissue is manually moved to the desired position on the chestwall, whereafter the strap is tightened to maintain the position. Treatment setup marks are placed on the skin peripheral to the breast and on the immobilization mold. RESULTS: Twelve patients with large/flaccid breasts were successfully treated with this device. The technical and physician staff find the reproducibility and acute treatment reactions to be acceptable. Anatomically, the use of this device reduces the volume of lung tissue otherwise included in the tangential fields in patients where the breast lies far lateral. In patients where the breast lies too far cephalad on the chestwall for tangential fields to clear the arm, repositioning of the breast with this device makes tangential fields possible. CONCLUSION: This repositioning appliance aids in the radiation treatment of patients with large or flaccid breasts and, in some instances, renders otherwise nontreatable patients treatable with radiation therapy.

Impact of cradle immobilization on setup reproducibility during external beam radiation therapy for lung cancer.

PURPOSE: To compare the setup accuracy during fractionated radiation therapy for two patient groups with lung cancer treated with and without an immobilization cradle. METHODS: Three hundred ninety-seven port films from 30 patients immobilized in the Alpha Cradle were compared with 329 port films from 30 patients who were not immobilized with the cradle. All patients were treated with curative intent for nonmetastatic lung cancer. The frequency of physician-requested isocenter shifts were compared in the two groups using a two-tailed chi-square test. Initial port films taken on the first day of treatment, routine films taken usually weekly during radiation therapy, and requested films taken after a requested shift were considered separately. The immobilization device consisted of a custom-made foam cradle that extended from above the head to the knees. Patients were generally treated with their arms above their heads, and treatment setup marks in the immobilized patients were placed on both the patients' skin and the immobilization cradle. For the noncradle patients, setup marks were placed only on the patients' skin. RESULTS: For the routine films, the frequency of physician-requested isocenter shifts was lower in immobilized patients than in the nonimmobilized group (p = 0.139). Most of this reduction was seen on oblique fields (p = 0.038). No benefits were seen among initial or requested films. The two groups were well balanced with regard to stage, age, field size, and total dose. CONCLUSIONS: The use of aggressive immobilization improves the setup reproducibility in patients receiving external beam radiation therapy for lung cancer, especially during treatment with oblique fields. This improvement in treatment accuracy might improve the therapeutic ratio.

Impact of setup variability on incidental lung irradiation during tangential breast treatment.

PURPOSE: This study aimed to determine the variability in treatment setup during a 5-week course of tangential breast treatment for patients immobilized in a customized hemibody cradle, to assess the relationship between the height of the lung shadow on the tangential port film and the percentage of lung volume irradiated, and to estimate the impact of setup variabilities on irradiated lung volume. METHODS: One hundred seventy-two port films were reviewed from 20 patients who received tangential beam treatment for breast cancer. The height of the lung shadow at the central axis (CLD) on each port film was compared to the corresponding simulator film as an assessment of setup variability. A three-dimensional dose calculation was performed, and the percentage of total lung volume within the field was correlated with the CLD. The three-dimensional dose calculation was repeated for selected patients with the location of the treatment beams modified to reflect typical setup variations. RESULTS: The CLD measured on the port films was within 3 mm of that prescribed on the simulator film in 43% (74 of 172) of the port films. The variation was 3-5 mm in 26%, 5-10 mm in 25%, and >10 mm in 6%. The height of the lung shadow correlated with the percentage of lung volume included in the radiation field (r2 = 0.6). Typical variations in treatment setup resulted in < or = 5% fluctuation in the absolute volume of ipsilateral lung irradiated. CONCLUSION: The current immobilization system used in our clinic provides a clinically acceptable reproducibility of patient setup. The height of the lung shadow is reasonably well correlated with the percentage of irradiated lung volume. During a typical 5-week course of radiotherapy, the ipsilateral irradiated lung volume fluctuates <5%.

Variability of the location of internal mammary vessels and glandular breast tissue in breast cancer patients undergoing routine CT-based treatment planning.

PURPOSE: To determine the variability of position of internal mammary vessels (IMV) and glandular breast tissue (GBT) in patients undergoing breast-conserving radiation therapy. To assess the frequency and magnitude of tangential field border shifts based on preradiation therapy (RT) computed tomography (CT) imaging in breast cancer patients. METHODS AND MATERIALS: Five hundred and ninety breast cancer patients irradiated between 9/94 and 3/98 underwent routine CT-based treatment planning. Two analyses were performed. First, the position of IMV and GBT, outlined on the central axis CT image, was determined relative to the midsternum in 111 patients irradiated during a 12-month period. In the second analysis, the difference between anticipated (pre-CT) and actual (CT-based) tangential field borders was assessed in 254 patients irradiated during a 2-year period. RESULTS: In the first analysis, the depth of the IMVs varied from 1 to 6 cm (median 2.4 cm). The lateral distance from the midsternum also varied widely (range 1.7 to 3.7 cm, median 2.5 cm). Similar variability was found in the position of the GBT. In the second analysis, CT information led to changes of anticipated field borders in 65% of patients. The lateral border was shifted in 56% of patients (anteriorly 18%, posteriorly 38%). When the patients were segregated based on internal mammary node (IMN) treatment, the medial border was shifted in 49% of patients when the IMNs were treated in the tangential fields and in 24% when the GBT only was treated. The frequency of lateral field border shifts was similar in both groups. CONCLUSIONS: The position of IMVs and GBT varies widely in breast cancer patients. Tangential field borders based on surface anatomy may not be ideal. Among 254 breast cancer patients, the field borders were shifted in 65% of patients when CT information was available. Thus, in most breast cancer patients, field borders are shifted when CT-based treatment planning is used.

Comparison of two repositioning devices used during radiation therapy for Hodgkin's disease.

PURPOSE: Patients irradiated for Hodgkin's disease are fixed in an immobilization cradle to improve repositioning. In the early 1990s, we changed our cradle system from a "short" upper torso cradle to an extended near-total body cradle that also includes the lower torso and thighs. In this study, we assess the impact of the extended cradle on the reproducibility of patient repositioning during irradiation of Hodgkin's disease. METHODS AND MATERIALS: A total of 782 port films of 56 patients treated immediately before and after the change-over were studied to assess positioning reproducibility. Patients treated prior to 1993 were positioned in the short cradle, while those treated 1993 and later were positioned in the extended cradle. All treatment were delivered via anterior and posterior fields and treatment areas above and below the diaphragm were considered separately and together. All treatment fields were simulated and the field shape was designed on anterior and posterior radiographs. Discrepancies in field placement between the simulation radiographs and subsequent port films were noted by a radiation oncologist and requests for position adjustment (both translational and rotational shifts) were noted. The number, magnitude, and direction of any physician-requested position adjustment on port films were retrospectively reviewed. For the purpose of scoring the frequency of field misplacements, when an adjustment was noted on two port films taken during the same treatment session (i.e., a left shift on both an anterior and a posterior port film), it was scored as only one event. A two-tailed chi-square test was used to compare the differences in requested shifts in the two patient groups. RESULTS: The study population consisted of 56 patients (31 short and 25 extended cradle) representing 92 treatment sites. A total of 782 port films representing 450 treatment setups were analyzed (292 above and 158 below the diaphragm). When all port films above the diaphragm (mostly mantle fields) are considered, position adjustments were requested in 13.4% (21 out of 157) of treatment setups with the upper torso cradle and in 5.9% (8 out of 135) of treatment setups with the extended cradle (p = 0.054). When all port films below the diaphragm (mostly paraaortic/spleen and pelvic fields) are considered, position adjustments were requested in 33.8% (27 out of 80) of treatment setups with the upper torso cradle and in 16.7 % (13 out of 78) of treatment setups with the extended cradle (p = 0.056). A reduction in the frequency of both translational and rotational adjustments were seen. When both treatment sites are combined, position adjustments were requested in 20.3% (48 out of 237) of treatment setups with the upper torso cradle and in 9.9% (21 out of 213) of treatment setups when the extended cradle was used (p = 0.0086). CONCLUSIONS: The extended cradle provides superior repositioning of patients undergoing radiation therapy for Hodgkin's disease. Differences observed in setup accuracy in this study underscore the importance of aggressive immobilization of patients with Hodgkin's disease. Increased accuracy of daily setup may provide an opportunity to improve the therapeutic ratio both by increased likelihood of tumor control and decreased risk of normal tissue complications.

Comparison of two head and neck immobilization systems.

PURPOSE: Accurate and reproducible patient positioning is fundamental to the success of fractionated radiotherapy. Concurrent with the introduction of three-dimensional treatment planning capabilities at our institution, a head and neck immobilization system consisting of a standard foam rubber head support and three casting strips was replaced by a customized mask-based device. This study was performed to analyze the impact of the customized immobilization system on the reproducibility of patient setup during irradiation of head and neck and brain tumors. METHODS AND MATERIALS: Patients treated from 1989-1991 were immobilized with the strip system while those treated from 1991-1995 were immobilized with the mask. All treatment fields were simulated and were treated on a 4 MV (where the strip, but not the mask, system was fixed to the treatment couch) or > or = 6 MV (where both the strip and the mask systems were fixed to the couch) accelerator. Port films were taken on the initial treatment day, routinely during treatment, and following shifts (requested). The number, magnitude, and direction of any isocenter shifts were retrospectively reviewed. A two-tailed chi square test was used to compare the differences in requested shifts in the strip and mask groups. RESULTS: The study population consisted of 69 brain tumor (35 strip, 34 mask) and 71 head and neck (37 strip, 34 mask) patients. A total of 1575 port films representing 1070 isocenter placements were analyzed. No differences between the immobilization systems was seen on the 4-MV accelerator (where the mask system was not fixed to the couch). On the > or = 6-MV units, the frequency of shifts was 16.1% versus 6.2% (p = 0.002) with the strips and mask, respectively. Almost all of the benefit was seen in the routine films, where the corresponding rates were 13.2% and 4.1% (p = 0.007). For the mask system, the rate of requested shifts on routine films was 4.1% (8/197) for the > or = 6-MV units and 14.5% (24/166) for the 4-MV unit (p = 0.001). CONCLUSION: Using the frequency of physician-requested isocenter shifts as an indicator of the accuracy of patient repositioning, the newer mask system appears to be an improvement over the previously used strip system, provided that the immobilization device is secured to the treatment couch. Increased accuracy of daily setup provides an opportunity to improve the therapeutic ratio both by increased likelihood of tumor control and decreased risk of normal tissue complications.