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Purpose Treatment of glioblastoma multiforme (GBM) continues to pose a significant therapeutic challenge, with most tumors recurring within the previously irradiated tumor bed. To improve outcomes, we must be able to identify and treat resistant cell populations. Rad51, an enzyme involved in homologous recombinational repair, leads to increased resistance of tumor cells to cytotoxic treatments such as radiotherapy. We hypothesized that Rad51 might contribute to GBM's apparent radioresistance and consequently influence survival. Methods and Materials A total of 68 patients with an initial diagnosis of GBM were retrospectively evaluated; for 10 of these patients, recurrent tumor specimens were used to construct a tissue microarray. Rad51 protein expression was then correlated with the actual and predicted survival using recursive partitioning analysis. Results Rad51 protein was elevated in 53% of the GBM specimens at surgery. The Rad51 levels correlated directly with survival, with a median survival of 15 months for patients with elevated Rad51 compared with 9 months for patients with low or absent levels of Rad51 ( p = .05). At disease recurrence, 70% of patients had additional increases in Rad51 protein. Increased Rad51 levels at disease recurrence similarly predicted for improved overall survival, with a mean survival of 16 months from the second craniotomy compared with only 4 months for patients with low Rad51 levels ( p = .13). Conclusion Elevated levels of the double-stranded DNA repair protein Rad51 predicted for an increase survival duration in patients with GBM, at both initial tumor presentation and disease recurrence.

Purpose : To evaluate the efficacy and toxicity of a stereotactic radiosurgery boost as part of the primary management of a minimally selected population of patients with malignant gliomas. Methods and Materials : Between June, 1991 and January, 1994 a stereotactic radiosurgery boost was given to 30 patients after completion of fractionated external beam radiotherapy. The study population consisted of 22 males and 8 females, with a ranged in age at treatment from 5 to 74 years (median: 54 years). Tumor volume ranged from 2.1 to 115.5 cubic centimeters (cc) (median: 24 cc). Histology included 17 with glioblastoma multiforme, 10 with anaplastic astrocytoma, 1 with a mixed anaplastic astrocytoma-oligodendroglioma, and 2 with a gliosarcoma. A complete resection was performed in 9 (30%) patients, while 18 (60%) underwent a subtotal resection, and 3 (10%) received a biopsy only. Fractionated radiation dose ranged from 44 to 62 Gy, with a median of 59.4 Gy. Prescribed stereotactic radiosurgery dose ranged from 0.5 to 18 Gy (median: 10 Gy), and the volume receiving the prescription dose ranged from 2.1 to 158.7 cc (median: 46 cc). The volume of tumor receiving the prescription dose ranged from 70–100% (median: 100%). One to four (median: 2) isocenters were used, and collimator size ranged from 12.5 to 50 mm (median size: 32.5 mm). The median minimum stereotactic radiosurgery dose was 70% of the prescription dose and the median maximum dose was 200% of the prescription dose. Results : With a minimum follow-up of 1 year from radiosurgery, 7 (23%) of the patients are still living and 22 (73%)_have died of progressive disease. One patient died of a myocardial infarction 5 months after stereotactic radiosurgery. Follow-up for living patients ranged from 12 to 45 months, with a median of 30 months. The 1- and 2-year disease-specific survival from the date of diagnosis is 57 [95% confidence interval (CI) 39 to 74%] and 25% (95% CI 9 to 41%), respectively (median survival: 13.9 months). No significant acute or late toxicity has been observed. Conclusions : Stereotactic radiosurgery provides a safe and feasible technique for dose escalation in the primary management of unselected malignant gliomas. Longer follow-up and a randomized prospective trial is required to more thoroughly evaluate the role of radiosurgery in the primary management of malignant gliomas.

Purpose : The development of a technique to provide sufficient radiation protection to previously irradiated spinal cord in such a manner that interstitial brachytherapy can be conducted after resection of a recurrent tumor and decompression of the cord. Methods and Materials : A technique was developed that uses multiple layers of gold foil that are applied around the thecal sac and nerve root sleeves to produce an enveloping radiation shield after resection of recurrent tumor. Once the layers of gold foil are in place, interstitial I 125 seeds are permanently placed in the bed of the tumor resection to prevent any recurrence from microcellular disease. The technique is described and its application in the case of a 28-year-old with a third recurrence of chondrosarcoma after external fractionated radiation therapy at the second to the fourth thoracic segments is reviewed. Results : This technique has been used in this first patient. An additional tumor dose of 120.0 Gy was delivered to the tumor bed while the spinal cord was calculated to receive only 1% of the dose over the life span of the implant. To date, this dose of radiation has prevented tumor recurrence for more than 18 months of follow-up. Conclusion : This technique of multiple layers of gold foil shielding over the spinal cord and nerve roots has the potential to be a useful tool for the shielding of a previously irradiated spinal cord in the setting of resection of recurrent tumor. It may also have a wider application to a number of other radiosensitive tumors where interstitial brachytherapy may be useful to provide additional treatment after external fractionated radiation therapy.

Purpose: This study was undertaken to answer the following questions in breast irradiation: (a) How many calculation planes are sufficient for three-dimensional (3-D) treatment planning? (b) Is pseudo-3-D planning system sufficiently accurate for 3-D treatment planning of a breast? Methods and Materials: We carried out dose calculations and differential dose-volume analysis on three representative patients covering the range of breast size encountered in a clinic. The breast volumes were reconstructed from computed tomography (CT) scans using three slices, five slices and the full CT scan respectively. An established 3-D dose algorithm and two pseudo-3-D commercial systems were used in the calculations. Comparison of isodose distributions were made between the central axis plane, a cephalic and a caudal plane 6 cm above or below the central axis respectively. Results: When comparing isodose distributions generated with conventional two-dimensional treatment planning with 3-D dose calculations, the former underestimated the size and magnitude of the hot spots in the medial and the lateral subcutaneous (SC) regions. When comparing the three-slice with the full CT model, while the three-slice model was found to be adequate for the “small” and the “medium” size patients, the full CT model provided a more accurate representation of dose distributions for the “large” patient. Comparison of a true 3-D algorithm with pseudo-3-D algorithms showed that while the latter systems were adequate for the “small” and the “medium” patients, significant differences were noted between the true 3-D and the pseudo-3-D algorithms for the “large” patient. Conclusion: For patients whose breast contours vary slowly within the tangential fields, a three-slice CT scan as well as a pseudo-3-1) approach appears to be adequate for clinical decision. However, for patients with large variation of contours within the tangential fields, a full scale CT scan with a true 3-D dose algorithm is more accurate than either the three-slice or the five-slice model.

Purpose: This Phase I trial tests the ability of a new hyperthermia device, the transrectal ultrasound probe, to heat the prostate gland, and evaluates the toxicity of transrectal ultrasound hyperthermia (TRUSH) given with concurrent standard external beam irradiation in the treatment of locally-advanced adenocarcinoma of the prostate. Methods and Materials: Between June, 1990 and August, 1991, 14 patients with American Urological Society Stage C 2 or D 1 adenocarcinoma of the prostate were treated with TRUSH concurrently with standard external beam radiotherapy to the prostate. Twenty-two heat treatments were delivered in 14 patients; 8 patients received two TRUSH procedures, each separated by 1 week. Patient age ranged between 53–86 (mean: 72) years. Three patients had well-, 6 patients had moderately-, and 5 patients had poorly-differentiated adenocarcinoma of the prostate. Karnofsky status ranged from 70–90. Standard radiotherapy to the prostate and periprostatic tissues was delivered using a four-field approach with 1.8-2 Gy daily fractions delivered 5 X/week to a total dose of 67–70 Gy calculated to the minimum tumor volume. TRUSH was delivered after transperineal placement of multipoint thermometry probes by a urologist, under transrectal ultrasound guidance. Two to three thermocouple probes containing seven sensors each were placed in the prostate in an attempt to sample temperatures throughout the gland. The sensor depth from the rectal wall ranged from 5–25 mm. Results: Thirty-six percent of all sensors were heated above 42.5°C averaged over 30 min; and all patients had at least some sensors within the prostate heated to temperatures ≥ 42.5°C. The average temperature of all sensors of all sensors (T ave ± s.d.) over all treatments, however, was only 41.9°C ± 0.9°C over 30 min. The maximum temperature for normal tissues outside the gland was 41.1°C ± 1.3°C. Treatments have been well-tolerated with few complications. Tolerance has been "good" in 1722, "fair" in 322, and "treatment limiting" in sol222 treatments secondary to position intolerance and/or pain. There has been one episode of hypotension related to narcotic administration and three episodes of rapidly resolving pain during hyperthermia treatment. Mild hematuria has occurred in 522, and moderate hematuria has occurred in 2/22 transperineal thermometer catheter placements. Conclusion: In conclusion, TRUSH is well-tolerated and has great potential for consistently heating the prostate gland. We anticipate that further equipment modifications will improve our ability to heat the entire prostate to temperatures > 42.5°C.

A Phase I study of interstitial thermoradiotherapy for high-grade supratentorial gliomas has been completed. The objective of this trial was to test the feasibility and toxicity of hyperthermia induced by ferromagnetic implants in the treatment of intracranial tumors. The patient population consisted of 16 males and 12 females, with a median age of 44 years and a median Karnofsky score of 90. Nine patients had anaplastic astrocytoma while 19 had glioblastoma multiforme. Twenty two patients were treated at the time of their initial diagnosis with a course of external beam radiotherapy (median dose 48.4 Gy) followed by an interstitial implant with Ir-192 (median dose 32.7 Gy). Six patients with recurrent tumors received only an interstitial implant (median dose 40 Gy). Median implant volume for all patients was 55.8 cc and median number of treatment catheters implanted per tumor was eighteen. A 60-minute hyperthermia treatment was given through these catheters just before and right after completion of brachytherapy. Time-averaged temperatures of all treatments were computed for sensors located within the core of (> 5 mm from edge of implant), and at the periphery of the implant (outer 5 mm). The percentage of sensors achieving an average temperature > 42 degrees C was 61% and 35%, respectively. Hyperthermia was generally well tolerated; however, there have been 11 minor toxicities, which resolved with conservative management, and one episode of massive edema resulting in the death of a patient. In addition, there were three major complications associated with the surgical implantation of the catheters. Preliminary survival analysis shows that 16 of the 28 patients have died, with a median survival of 20.6 months from diagnosis. We conclude that interstitial hyperthermia of brain tumors with ferromagnetic implants is feasible and carries significant but acceptable morbidity given the extremely poor prognosis of this patient population.

Selective heating of irregularly shaped tumors at depth can now be accomplished through focussing and controlled scanning of energy deposition patterns by ultrasound. A scanned focussed ultrasound (SFUS) hyperthermia system developed at the University of Arizona has been used to deliver 220 treatments to 87 tumors in 71 patients with extracranial malignancies between October 1986 and May 1990. Patients received an average of three SFUS hyperthermia treatments, spaced weekly, during ongoing fractionated radiotherapy. The most common anatomic sites treated were the pelvis (22 patients), chest wall or breast (14), neck (8), and axilla (7), while the most common histologies were adenocarcinoma (36), squamous cell carcinoma (11), and melanoma (10). Concurrent radiotherapy was delivered (range 1000–7640 cGy, mean 4320 cGy) to 67 SFUS hyperthermia patients; 4 received concomitant chemotherapy. Tumor volumes ranged from 1–2100 cubic centimeters (mean 325 cc), and 75% were located at depths > 3 cm from skin. A 62% overall response rate was observed, with 22% of treated tumors demonstrating a complete response (defined as complete disappearance of treated tumor), and 40% exhibiting a partial response (defined as >- 50% reduction in tumor volume). Dramatic local pain reduction was achieved in 42% of the tumors treated. The acute tolerance of SFUS hyperthermia was quite good, and chronic toxicities (persistent skin blisters/burns) were identified in two patients. The versatility of the SFUS system is discussed, as well as its future potential for improving control of advanced loco-regional malignancies treated with curative intent.

A Phase I clinical trial has been initiated to determine the feasibility, tolerance, and toxicity of interstitial thermoradiotherapy in the treatment of high-grade supratentorial brain gliomas. Hyperthermia was delivered by means of thermally-regulating ferromagnetic implants afterloaded into stereotactically placed plastic catheters. Heat treatments were given immediately before interstitial irradiation; in addition, five patients received a second heat treatment at the completion of brachytherapy. The desired target temperature for the 60-minute hyperthermia session was between 42 degrees C and 45 degrees C. Following hyperthermia, the catheters were afterloaded with Ir-192, which delivered a variable radiation dose of 14-50 Gy depending on the clinical situation. Interstitial irradiation was supplemented with external beam radiotherapy (40-41.4 Gy) in patients with previously untreated tumors. A total of 14 patients (4 males, 10 females) have been treated to date on this protocol. Eleven of the patients had a diagnosis of glioblastoma multiforme, whereas three had anaplastic astrocytoma. The mean implant volume was 61.5 cm3 (range: 9-119 cm3); the median number of interstitial treatment catheters implanted was 19 (range: 7-33). Continuous temperature monitoring was performed by means of multisensor thermocouple probes inserted in the center as well as in the periphery of the tumor. Of the 175 monitored intratumoral points, 83 (47%) had time-averaged mean temperatures of greater than 42 degrees C, and only 12 sensors (7%) exceeded a temperature of 45 degrees C. Among the 19 heat treatments attempted, there have been four minor acute toxicities, all of which resolved with conservative medical management and one major complication resulting in the demise of a patient. These preliminary results indicate that ferromagnetic implants offer a promising new approach to treating brain tumors with hyperthermia.

Purpose: To report on a retrospective analysis of the cumulative experience from eight institutions using the GliaSite Radiotherapy System as a brachytherapy boost in the initial management of glioblastoma multiforme. Methods and Materials: Eight institutions provided data on 20 patients with histologically proven glioblastoma multiforme with a median age of 59 years (range, 39–76) and median Karnofsky performance scale of 80 (range, 50–100). After maximal surgical debulking, patients were treated with GliaSite brachytherapy to a median dose of 50 Gy, followed by external beam radiotherapy to a median dose of 60 Gy (range, 46–60 Gy), for a cumulative dose escalation of 110 Gy (range, 84–130 Gy). Results: The average survival for this study population was 11.4 months (range, 4–29). When the patients’ survival was compared with that of historical controls according to their Radiation Therapy Oncology Group recursive partitioning analysis class, the average survival was increased by 3 months (95% confidence interval, 0.23–4.9) corresponding to a 43% increase (p = 0.033). Three patients (14%) experienced Radiation Therapy Oncology Group Grade 3 central nervous system toxicity. Of the treatment failures, 50% were >2 cm from the edge of the balloon. Conclusion: The results of this analysis have demonstrated that dose escalation (>100 Gy) with GliaSite is well tolerated and associated with minimal toxicity. Local control improved with the use of GliaSite brachytherapy. The putative survival advantage seen in this study needs to be interpreted with caution; nevertheless, the data provide sufficient justification to investigate the potential role of radiation dose escalation in conjunction with GliaSite in the initial treatment of glioblastoma multiforme.

Purpose: To determine the prognostic factors for radiographic response and its prognostic value for subsequent survival in patients undergoing whole-brain radiotherapy (WBRT) for brain metastases. Methods and Materials: Five hundred fifteen eligible patients were randomized in a phase III trial evaluating WBRT and supplemental oxygen with or without efaproxiral, an allosteric modifier of hemoglobin that reduces hemoglobin oxygen-binding affinity and enhances tumor oxygenation, potentially increasing tumor radiosensitivity. Brain images were obtained at baseline and at scheduled follow-up visits after WBRT. Landmark analysis was used to assess the ability of response at selected time points to predict subsequent survival. Logistic regression was used to assess determinants of response at 3 months. Results: Treatment arm, Karnofsky Performance Status, presence or absence of liver metastases, and primary site were all determinants of response at the 3-month follow-up visit, with patients in the efaproxiral arm experiencing a 67% greater odds of response at this visit ( p = 0.02). Response at 3 and 6 months was a significant prognostic factor for longer subsequent survival. Conclusions: The 3-month scan is a valuable prognostic factor for subsequent survival in patients with brain metastases treated with WBRT. Patients in the efaproxiral arm had a higher response rate at 3 and 6 months than those in the control arm.

Purpose: To evaluate the effectiveness of postoperative high-dose-rate (HDR) vaginal cuff irradiation alone (1500 cGy in 3 fractions) in patients with Stage Ib and Ic endometrial cancer. Methods and Materials: This is a retrospective review of 102 patients with Stage Ib and Ic endometrial cancer treated with a hysterectomy and postoperative HDR intracavitary therapy alone during the period of 1/1/90–12/31/96. Each patient received 1500 cGy in 3 weekly treatments, dosed to a depth of 0.5 cm. Pathologic features such as depth of invasion, tumor grade, lower uterine segment (LUS) involvement, and lymphvascular invasion (LVI) were evaluated for their impact on recommended postoperative treatment. All survival curves were generated utilizing Kaplan-Meier methods and all statistical comparisons were via a Wilcoxon rank sum test. Results: The 5-year actuarial overall survival (OS) is 84% and the 5-year disease-free survival (DFS) is 93%. Locoregional disease control (pelvic control) was excellent with 97% of the patients free of pelvic disease at 5 years. Of the three pelvic failures only one was in the vaginal cuff. LVI, LUS involvement, Grade 3 and/or outer third myometrial involvement were identified in 41 patients. Thirty-one of these patients underwent a lymphadenectomy and there were two regional failures within this increased-risk group. Conclusions: We obtained an excellent level of locoregional control with minimal morbidity and minimal time commitment for treatment with vaginal HDR brachytherapy alone. Our dose per fraction and total dose is lower than most reported series and there is no apparent loss in locoregional control. In addition, intermediate-risk patients and patients with an increased risk of recurrence (Grade 3, outer third myometrial involvement, LVI, LUS) may be treated with cuff irradiation alone, after surgical staging and a negative lymphadenectomy.

Controversies exist regarding the use of radiation therapy in the treatment of vulvar carcinoma. A retrospective review was performed to evaluate our institution's experience with surgery and radiation for this disease.The medical records of 47 patients treated for squamous cell carcinoma of the vulva at our institution (1974-1992) were reviewed for TNM stage (AJCC criteria), treatment modality, and associated 5-year local control and survival based on Kaplan-Meier analysis.Twenty-eight patients (60%) presented with Stage I and II disease and their 5-year survival was 69%. Stage III patients accounted for 12 (25%) of the patients and their 5-year survival was 73%. Seven patients presented with Stage IV disease and five died within 13 months of diagnosis after predominantly palliative therapy. The 40 patients with Stages I, II, and III disease were treated aggressively and were further evaluated for treatment-modality-associated survival and local control. Radiation therapy was used as primary treatment in nine patients, of whom seven were treated with radiation alone and two were treated postoperatively after wide excision. Surgery alone was performed in 31 patients consisting of either radical vulvectomy (20 patients) or wide excision (11 patients). When comparing outcomes of radical vulvectomy vs. radiation therapy, we noted that the 5-year actuarial survivals were comparable (74% for either modality), despite the presence of more favorable prognostic factors in the group treated with radical vulvectomy. Patients treated with wide excision alone had a trend for a poorer 5-year actuarial survival (51%) and local control (50%).Radical vulvectomy offers good locoregional control and survival. This retrospective review further supports the use of radiation therapy with conservative surgery as an alternative treatment option for patients with vulvar carcinoma treated with curative intent. In contrast, the use of wide excision alone should be performed with caution due to a higher locoregional failure rate. The role of appropriately prescribed radiation therapy should be further investigated in prospective clinical trials.

Purpose: The current sheet applicator (CSA) is a newly developed microwave hyperthermia device. Advantages over commercial microwave applicators include its small size and high ratio of heating area to physical aperture area. These physical characteristics make the CSA excellent for heating constricted areas and allow the use of arrays of CSAs over large surfaces. This study examines the clinical efficacy of the CSA for heating superficial malignant tumors. Methods and Materials: From December 1989 through October 1991, 19 patients with recurrent or metastatic superficial malignant tumors were treated once or twice weekly to 30 hyperthermia fields using one to four CSAs. Each field received from one to four hyperthermia treatments for a total of 74 treatments. The treatment objective was to elevate the tumor temperature to a minimum of 42.5°C for 30 min (2 patients) or 60 min (17 patients). Intratumor temperatures were measured with percutaneous fiberoptic thermometry probes. All patients received concurrent fractionated radiation therapy with total dose ranging from 20 to 65 Gy (median 46 Gy). Seventeen of the 30 fields had been previously irradiated to a median dose of 50 Gy. Results: Mean values for the maximum temperature, average temperature, and minimum temperature were 43.6°C ± 1.0, 42.2°C ± 1.4, and 41.0°C ± 1.5, respectively. Mean values for T 50 and T 90 were 42.2°C ± 1.1 and 41.0°C ± 1.3, respectively. The overall response rate for all assessable fields was 96%. Only three responding tumors have progressed with a median follow-up period of 6 months. Treatment related morbidity was generally mild and self-limited. Conclusion: The CSA is a promising new microwave hyperthermia device capable of heating superficial tumors to therapeutic temperatures. When used in combination with radiotherapy, response rates are excellent without excessive toxicity.

We have initiated a Phase I clinical trial of interstitial hyperthermia induced with inductively heated ferromagnetic implants in combination with Ir-192 implants for glioblastomas and anaplastic astrocytomas of the brain. For speed and accuracy of the implant procedure, and to control the radiation and thermal dose, a stereotaxic frame is used to position a template. We have modified the Brown-Roberts-Wells frame to be used with a variety of templates which we designed. On the morning of the implant procedure, a CT scan is done, and a CT-based treatment plan is then completed before the patient goes to the operating room. We also describe the CT-based treatment planning system developed to accommodate the template-guided implant and illustrate its clinical use.

Purpose: To compare the survival of two groups of patients with supratentorial malignant gliomas who were treated on two sequential protocols with either interstitial thermoradiotherapy or with interstitial irradiation without hyperthermia. 1Methods and Materials: Between 1988–1992, patients with anaplastic astrocytoma or glioblastoma multiforme were treated at the University of Arizona on a Phase I/II protocol of interstitial thermoradiotherapy with ferromagnetic seeds. The treatment protocol consisted of debulking surgery, a course of external beam radiotherapy and hyperthermia given immediately before and after brachytherapy. The survival of patients so treated was compared with that of a similar group of patients treated with interstitial brachytherapy alone at the Barrows Neurological Institute between 1982–1990. Results: Twenty-five patients with primary tumors treated at the time of initial presentation with thermoradiotherapy were compared with a control group of 37 patients treated with interstitial brachytherapy alone. All primary patients were followed for a minimum of 34 months post implant. Multivariate analysis based on proportional hazards models showed that hyperthermia ( p = 0.027), patient age ( p ≤ 0.00001) and histology (anaplastic astrocytoma vs. glioblastoma multiforme, p = 0.0017) were the only factors significantly associated with survival in this data set. From the fitted model, the hazard of dying when treated with hyperthermia was .53 times (95% confidence intervals 0.29–0.94) than that of the control group. In addition, we treated a small group of patients with recurrent tumors (13 with brachytherapy alone, and eight with thermoradiotherapy) and found no survival difference ( p = 0.62). Conclusion: Within the constraints of the selection factors and the different treatment parameters used in these studies, we conclude that an interstitial thermoradiotherapy boost confers a statistically significant survival benefit to patients with primary high grade gliomas when compared to interstitial brachytherapy alone.

Adolescent and young adult patients with pelvic sarcomas continue to have a poor prognosis with standard combination chemotherapy and local irradiation. In addition to a significant risk of local failure, these patients are at high risk for systemic relapse. Twenty-three consecutive patients with Ewing's sarcoma, alveolar rhabdomyosarcoma, undifferentiated sarcoma, or malignant peripheral neuroepithelioma originating in the pelvis were treated with short, intensive combined modality therapy. This approach integrates 5 cycles of VADRIAC chemotherapy (Vincristine, Adriamycin, Cyclophosphamide) with high dose irradiation to the primary lesion (55-60 Gy) and sites of gross metastatic disease (45-50 Gy). Following achievement of a complete response, intensification therapy consisting of total body irradiation (TBI) (8.0 Gy), high dose VADRIAC chemotherapy, and autologous bone marow transplantation is given. All therapy is completed within 6-7 months. No maintenance chemotherapy is given; no surgery is intended. Of the twenty-three patients with pelvic sarcomas treated on this combined modality protocol, 22 achieved a complete remission. Local control was achieved and maintained in all twenty-three patients. With a median follow-up of 21 months since initiation of treatment, there have been nine relapses (all systemic). Seven relapses occurred among the thirteen patients who presented with overt metastatic disease and the other two relapses were among the ten patients with localized disease at presentation. All seven metastatic patients who relapsed have died, whereas both of the relapsed localized patients remain alive. Acute and late toxicities have been acceptable using this aggressive combined modality approach. Induction chemotherapy had a significant impact on reduction of the typically large (greater than 10 cm diameter) soft tissue mass associated with these pelvic tumors, thus facilitating achievement of local control by high dose irradiation. Of 18 patients with measureable soft tissue tumor, all experienced a partial response (greater than 50% reduction in size) following the initial two cycles of chemotherapy given prior to local irradiation. In conclusion, this short, intensive chemoradiotherapeutic regimen is highly effective in controlling the primary lesion (100% local control) and inducing a complete response in a high proportion (96%) of these high risk pediatric and young adult patients with pelvic sarcomas. The role of TBI as "systemic" adjuvant therapy to control micrometastatic disease is discussed as still under investigation.

Small-cell osteosarcoma is an entity which shares some clinical and pathological features with both classic osteosarcoma and Ewing's sarcoma of bone. While noted to be "not radiosensitive" when first described, a retrospective review the National Cancer Institute experience of five patients with small-cell osteosarcoma treated with radiation therapy following biopsy (three pts) or limited excision (two pts) showed local control in all five patients with two long-term disease-free survivors (12, 18 years). This compares to three patients treated with surgery alone where one patient failed locally and one patient is a long-term disease-free survivor (7 years). We have studied the in vitro radiation response of a recently established small-cell osteosarcoma cell line (TC-252) and compared its response with that of a classic osteosarcoma cell line (U2-OS) and an Ewing's sarcoma cell line (5838). The small-cell osteosarcoma line responded with a similar Do and extent of PLDR compared to the Ewing's line and was different from the in vitro radiation response of classic osteosarcoma. Based on this small clinical series and the in vitro radiation studies, we conclude that small-cell osteosarcoma is a radioresponsive tumor. Definitive radiation therapy or conservative surgery plus radiation therapy are effective alternative therapeutic options, compared to ablative surgery, for the local treatment of this uncommon bone tumor of children and young adults.