Pancreatic cancer: treatment with neutron irradiation alone and with chemotherapy.

PURPOSE: To evaluate neutron irradiation alone and with chemotherapy to treat inoperable pancreatic cancer. MATERIALS AND METHODS: Between 1977 and 1994, 173 patients (60 men, 113 women, aged 43-77 years [mean, 59 years]) with unresectable adenocarcinoma of the exocrine pancreas were treated, 106 with neutron irradiation alone and 67 with concomitant chemotherapy (fluorouracil [5-FU]). At follow-up, which was performed at 2-month intervals until death (range, 4-64 months), clinical status was recorded, noting the presence of overt metastasis and the onset of any major complications. Actuarial (Kaplan-Meier) survival tables were computed for both groups. RESULTS: For neutron irradiation alone and neutron irradiation plus chemotherapy, median survival times were 6 months and 9 months, respectively; actuarial survival rates at 3 years were 0 and 7%, respectively; major reactions (grade 3 or higher [scale of the Radiation Therapy Oncology Group and European Organization for Research and Treatment of Cancer]) occurred in 19 (18%) and 17 (25%) patients, respectively; and severe complications (grade 4) occurred in five (5%) and four (6%) patients, respectively. Most deaths were due to metastatic disease rather than to failure of local control. CONCLUSIONS: Neutron irradiation obliterated pancreatic adenocarcinoma at the primary site but has no effect on long-term survival. With more effective concomitant chemotherapy to prevent metastasis, local control of pancreatic cancer with neutron irradiation could lead to increased long-term survival.

Neutron irradiation of human pelvic tissues yields a steep dose-response function for late sequelae.

PURPOSE: Analysis of the dose-response function in normal tissues following pelvic irradiation for carcinoma of the prostate. METHODS AND MATERIALS: A homogeneous group of 136 patients with locally advanced carcinoma of the prostate were treated with the Fermilab high-energy neutron beam at three dose levels: 19, 20.4, and 21 Gy, using the same treatment plan and fractionation scheme for all patients. RESULTS: Tumor control rates were about 83% at the three dose levels studied. However, the normal tissue complication rate (late sequelae) varied with dose: 0 out of 5 at 19 Gy, 5 out of 58 (8.6%) at 20.4 Gy, and 9 out of 73 (12.3%) at 21 Gy. CONCLUSIONS: Neutron therapy to the pelvis reveals a steep dose-response function for late effects with a coefficient of variation of only 11%. This is lower than that usually observed with photons or with less uniform clinical data sets, and may be characteristic for well-planned high-LET radiotherapy.

Combined modality treatment using BID radiation for locally advanced non-small cell lung carcinoma.

BACKGROUND: From February 1988 to August 1991, 82 patients were treated on Phase II trial of split-course multimodality treatment for locally advanced, non-small cell lung cancer (NSCLC). METHODS: Treatment consisted of twice-daily radiation (150 cGy/fraction) delivered with concomitant infusional cisplatin, etoposide, and fluorouracil for 1 week every third week. Patients were classified before initial treatment as either potentially resectable (eligible for surgery [ES]) or ineligible for surgery (IES). The ES group consisted of 38 Stage IIIA and 7 Stage IIIB patients. The IES group had 5 patients staged as IIIA and 32 staged as IIIB. Most patients were staged clinically. ES patients received three cycles of treatment (39 Gy) before resection. IES patients received four cycles (60 Gy) delivered with curative intent. RESULTS: Thirty-nine of 45 ES patients underwent resection. The pathologic response rate was 27%. Three-year actuarial local control was 86% for 41 evaluable ES patients. Three-year actuarial survival for the whole ES group was 39%, with a median follow-up for living patients of 32 months. The IES group faired less well, with an 18% 3-year actuarial survival. Treatment was well tolerated with a median weight loss of one-half pound, mild or moderate pneumonitis in 5%, mild esophagitis in 15%, and severe nausea and/or vomiting in 10% of patients. Treatment-related mortality was 5%. CONCLUSIONS: Patients treated with conventional radiation alone for Stage III NSCLC are rarely cured. This well tolerated Phase II study demonstrated encouraging results for such patients. Both local control and survival appeared promising, especially in patients rendered resectable after combined-modality treatment.

Isolated vaginal recurrences of endometrial carcinoma.

PURPOSE: The authors undertook this study to evaluate the results of radiation therapy (RT) for vaginal recurrence in early stage endometrial carcinoma. MATERIALS AND METHODS: Between 1964 and 1987, 34 patients with isolated vaginal recurrences of endometrial carcinoma were treated with RT. The records were reviewed for outcome and prognostic factors, such as location of tumor recurrence, time to recurrence, size of tumor at recurrence, tumor differentiation, and total radiation dose delivered at RT. RESULTS: With a median follow-up of 48 months, the 5-year actuarial survival and disease-free survival rates were 68% +/- 4 and 60% +/- 3, respectively. Results were statistically significant for some prognostic factors, including time to tumor recurrence and total radiation dose delivered at RT to the recurring tumor. CONCLUSION: Long-term survival can be obtained for patients with an isolated vaginal recurrence of endometrial cancer treated with aggressive local-regional radiation therapy.

Salvage whole abdomen radiation therapy: its role in ovarian cancer.

PURPOSE: In spite of high initial response rates, many patients with epithelial ovarian carcinoma eventually fail their primary treatment. Further treatment with second-line regimens has been ineffective in producing durable responses. Thus, whole abdomen radiation therapy was evaluated as a salvage therapeutic modality as to its feasibility, efficacy, and toxicity. METHODS AND MATERIALS: Between June 1983 and June 1990, 44 patients who failed one or more chemotherapeutic regimens were treated with whole abdomen radiation therapy. Forty patients had epithelial carcinoma of the ovary and the remaining had primary adenocarcinoma of the peritoneal cavity. Radiation was delivered with an open-field technique and 2500 cGy were planned to the whole abdomen, with a boost when indicated. Prior to radiation, the amount of residual disease after debulking was noted to be microscopic in one-half of the patients and macroscopic in the other half. Pelvis alone was the site of residual disease in 14 patients, and upper abdominal involvement was found in 30. RESULTS: Five patients (11%) were unable to complete the planned therapy secondary to acute toxicity. The 4-year actuarial survival and recurrence-free survival rates for the entire group were 23% and 22%, respectively. The survival and recurrence-free survival rates for the group with microscopic residual disease at 37% and 42% were significantly better than those for the patients with macroscopic residual disease at 9% and 5% (p < 0.005; p < 0.001) at 4 years, respectively. Patients with disease limited to pelvis only had a recurrence-free survival of 56% compared to 0% when the upper abdomen was involved (p < 0.005). The abdomino-pelvic cavity was the first site of recurrence in 28 of 31 patients in whom the site of recurrence could be determined. Eight patients (18%) experienced bowel complications, of whom five needed surgical intervention. CONCLUSIONS: Whole abdomen radiation therapy with a pelvic boost is feasible with acceptable acute and late toxicity. It is effective in patients with minimal residual disease.

Fast neutron radiotherapy for locally advanced prostate cancer. Final report of Radiation Therapy Oncology Group randomized clinical trial.

Between June 1977 and April 1983 the Radiation Therapy Oncology Group (RTOG) sponsored a Phase III randomized trial investigating the use of fast neutron radiotherapy for patients with locally advanced (Stages C and D1) adenocarcinoma of the prostate gland. Patients were randomized to receive either conventional photon radiation or fast neutron radiation used in a mixed-beam (neutron/photon) treatment schedule. A total of 91 analyzable patients were entered into the study, and the two patient groups were balanced with respect to the major prognostic variables. Actuarial curves are presented for local/regional control and "overall" survival. Ten-year results for clinically assessed local control are 70% for the mixed-beam group versus 58% for the photon group (p = 0.03) and for survival are 46% for the mixed-beam group versus 29% for the photon group (p = 0.04). This study suggests that a regional method of treatment can influence both local tumor control and survival in patients with locally advanced adenocarcinoma of the prostate gland.

Combined modality therapy for stage III non-small cell lung carcinoma: results of treatment and patterns of failure.

Patients with Stage III non-small cell lung carcinoma continue to pose a therapeutic problem with dismal cure rates. In an effort to improve on these results, 129 patients with biopsy-proven clinical Stage III non-small cell lung carcinoma from November 1982 through November 1987, were entered into two consecutive Phase II studies at Rush-Presbyterian-St. Luke's Medical Center. Treatment in the first study consisted of Cisplatin and 5-Fluorouracil infusion with concomitant split course radiation; in the second Etoposide was added. Radiation and chemotherapy were given simultaneously on days one through five of each cycle in a preoperative fashion for four cycles in patients considered eligible for surgery and in a definitive fashion for six cycles in patients considered ineligible for surgery. Radiation was given in 2 Gy fractions for a planned preoperative dose of 40 Gy and a definitive dose of 60 Gy. Surgical resection was attempted four to five weeks later in patients treated preoperatively. Thus, 83 patients were treated preoperatively and 46 definitively. Eighty-three patients (64%) had IIIA disease and IIIB disease was found in the remainder of the patients. Sixty-two patients (75%) in the eligible for surgery group had a thoracotomy after the combined treatment with a resectability rate of 97% and an operative mortality rate of 5%. There were 17 patients (27%) with no evidence of residual cancer in the resected specimen. Three-year survival for the eligible for surgery group at 40% was significantly better than 19% observed in the ineligible for surgery group (p = 0.003). Seventy-six percent of the patients with no residual cancer in the resected specimen are recurrence-free at three years compared to 34% of the patients with gross residual. A total of 81 patients have failed after their treatment; 49 (59%) in the eligible for surgery group and 32 (70%) in the ineligible for surgery group. Of all the patients who failed, local failure alone and as a component occurred in 21 (26%) and 36 (44%) patients, respectively. Failure in distant sites alone was noted in 56% of the overall failures. Severe toxicity was unusual. There were three treatment related deaths (2%). Radiation esophagitis and pneumonitis were only mild to moderate seen in less than 10% of the patients. Survival rates and patterns of failure according to the stage of the disease, histology, treatment group and pathologic response will be presented in detail.

Results of radiotherapeutic management of primary carcinoma of the vagina.

Forty-five previously untreated patients with primary carcinoma of the vagina were treated with curative radiotherapy from 1965 through 1985. All patients were staged according to the FIGO system. One patient was classified as Stage 0, 15 as Stage I, 22 as Stage II, 6 as Stage III, and 1 as Stage IV. Treatment consisted of intracavitary irradiation alone in Stage 0 patients. Stage I patients received intracavitary/interstitial irradiation alone or in combination with external irradiation and an implant when feasible. When treated with an implant only, the total tumor dose delivered was between 65-70 Gy. External irradiation consisted of delivering a dose of 45-50 Gy over a period of 4 1/2-5 weeks to the whole pelvis to treat the regional lymph nodes. An additional dose of 20-25 Gy was delivered to the site of original involvement using an implant when feasible. If not technically feasible, as in advanced stages, the patient was treated with additional external irradiation to a total dose of 65-70 Gy by a shrinking field technique. All patients except one were followed either until death or for a minimum of 2 years. The actuarial 5-year survival rates were 100% for Stage 0, 78% for Stage I, and 71% for Stage II patients. None of the patients with Stage III or IV disease survived. Of the patients who recurred, all but two did so within 16 months after diagnosis. Pelvic recurrence as the first site of recurrence occurred in 86% of the patients who recurred. Distant recurrence as a component occurred in 20% of all failures. Complications as a consequence of therapy occurred in 18% of the patients. Vaginal necrosis that healed with conservative treatment was seen in four patients and the other four patients had rectal complications of varying severity. Thus, curative radiotherapy is an effective method of treatment, with acceptable morbidity, in patients with early stage primary carcinoma of the vagina.

Combined modality therapy for locally advanced non-small cell lung carcinoma.

Multi-modality treatment consisting of cisplatin, VP-16, and 5-fluorouracil chemotherapy given concomitantly with external beam radiation was used to treat 64 patients with locally advanced Stage III non-small cell lung carcinoma. This regimen was used in a preoperative fashion for four cycles in patients considered surgically resectable and with curative intent for six cycles in the remainder of patients. The clinical response rate for the entire group was 84% and the overall local control rate was 74%. The median survival was 13 months with a median follow-up for live patients of 19 months. The actuarial 3-year survival and disease-free survival rates were 30% and 23%, respectively. Histologic complete response was 39% and appeared to predict for survival. The 3-year actuarial survival and disease-free survival rates for 23 resected patients were 69% and 45%, respectively, with the complete histologic responders having a disease-free survival of 78%. The pattern of first recurrence did not appear to differ by histology or presence of lymph nodes in this subset of patients. The actuarial 3-year survival and disease-free survival rates for inoperable patients receiving six cycles of treatment were 18% and 23%, respectively. The local control was 67% with the majority of these patients having Stage IIIB disease. The Mountain International staging system appeared to predict for operability, local recurrence, and survival. This concomitant treatment regimen is feasible, with the major toxicities being leukopenia, nausea, and vomiting.

High energy (42-66 MeV reactions) fast neutron dose optimization studies in the head and neck, thorax, upper abdomen, pelvis and extremities.

Five hundred and fifty patients were entered into a set of dose-searching studies designed to determine normal tissue tolerance to high energy (42-66 MeV reactions) fast neutrons delivered in 12 equal fractions over 4 weeks. Participating institutions included: The Fermilab (66 MeV p+----Be), The University of Washington (50 MeVp+----Be), U.C.L.A. (45 MeVH-----Be), M.D. Anderson Hospital (42 MeVH-----Be), and The Cleveland Clinic (42 MeVp+----Be). Patients were stratified by treatment facility and then randomized to receive 16, 18 or 20 Gy for tumors located in the upper abdomen or pelvis, and 18, 20 or 22 Gy for tumors located in the head and neck, thorax or extremities. Following completion of the randomized protocols, additional patients were studied at the 20.4 Gy level in the head and neck, thorax and pelvis. Normal tissue effect scoring was accomplished using the RTOG-EORTC acute and late normal tissue effect scales. Acute Grade 3 + toxicity rates in the head and neck were 19% for 20/20.4 Gy and 20% for 22 Gy. Time adjusted late toxicity rates in the head and neck at 12 months were 15% for 20/20.4 Gy and 0% for 22 Gy. The 18 Gy treatment arm of the head and neck protocol was dropped early in the study after only two patients were accrued. For cases treated in the thorax, acute Grade 3 + toxicity rates were 6% for 18 Gy, 15% for 20/20.4 Gy and 7% for 22 Gy. Late toxicity rates at 12 months were 0% for 18 Gy, 11% for 20/20.4 Gy and 18% for 22 Gy. Acute Grade 3+ toxicity rates in the upper abdomen were 0% for 16 Gy, 8% for 18 Gy and 12% for 20 Gy. There were no Grade 3 + late toxicities in the upper abdomen. In the pelvis, acute Grade 3 + toxicity rates were 0% for 16 Gy, 3% for 18 Gy and 3% for 20/20.4 Gy. Late Grade 3 + toxicities at 24 months were 20% for 16 Gy, 5% for 18 Gy and 24% for 20/20.4 Gy. In extremities, acute Grade 3 + toxicity rates were 7% for 20 Gy and 21% for 22 Gy while at 12 months, late Grade 3 + toxicity rates were 14 and 35%, respectively. The 18 Gy treatment arm of the extremities protocol was dropped early in the study after only two patients were accrued. Factors associated with normal tissue effects in addition to treatment dose are discussed.

Preoperative radiation therapy in regionally localized stage III non-small cell lung carcinoma: long-term results and patterns of failure.

Seventy-four patients from January 1975 through December 1982, with clinical Stage III Mo non-small cell carcinoma of the lung were treated at our Medical Center with a course of pre-operative radiation therapy to be followed by surgical resection. Radiation therapy consisted of delivering a total dose of 40 Gy with 200 cGy per fraction over a period of 4 weeks to the primary tumor in the lung and the regional lymph nodal areas. Surgical resection was attempted 4 weeks later. Fifty-eight percent of the patients had squamous cell carcinoma whereas the remaining had other histologies like adenocarcinoma, large cell carcinoma, or a combination thereof. All the patients except two were followed up to a minimum of 5 years or until death. Sixty-four patients (82%) had T3 tumors whereas mediastinal nodal involvement was found in 41 patients (55%). Fifteen patients (20%) did not have the operation because of tumor progression, patient's refusal or death. All but two surgically treated patients had tumor resection. Of these 19% had histologically negative specimens, 9 patients (16%) had microscopic disease only, and 37 patients had gross residual disease at the time of surgery. The actuarial 5-year survival and recurrence-free survival rates for the entire group were 20% and 24%, respectively. Patients with a pathologic response had an actuarial recurrence-free survival rate of 53% at 5 years whereas only 17% of those with gross residual disease at surgery had remained recurrence-free at 5 years. One-half of the patients with clinically uninvolved nodes were living recurrence-free at 5 years whereas only 20% of the patients with N2 disease did so. The patterns of failure according to the histology and stage of the disease will be presented.

Technique for breast irradiation using custom blocks conforming to the chest wall contour.

A technique for the treatment of the breast and regional nodes is presented. The technique involves the use of tangential fields to treat the breast and chest wall. Customized blocks which conform to the slope of the chest wall are made for each tangent field. Simulation and treatment with this technique requires no special equipment. The setup is simple and quick. A three-field technique is also described using the custom half-beam blocks; this technique avoids the use of tangential field corner blocks, thus simplifying simulation and treatment.

Accelerated fractionation radiation therapy for liver metastases: selection of an optimal patient population for the evaluation of late hepatic injury in RTOG studies.

The palliation of hepatic metastases represents a major therapeutic problem in oncology. The generally unfavorable prognosis of patients with liver metastasis may complicate the evaluation of the efficacy and toxicity of various therapeutic modalities. The Radiation Therapy Oncology Group (RTOG) is evaluating new accelerated fractionation schemes for hepatic irradiation. In designing this study it became necessary to identify a favorable subpopulation of patients with an expected median survival of 6 months in whom the late effects of treatment could be evaluated. Data from two RTOG liver metastases studies (7605 and 8003) were analyzed using multi-variate techniques. Cases with a serum bilirubin level of greater than 1.5 mg%, performance score of less than 50, and gastric or pancreatic primary carcinomas were initially excluded because of the adverse influence of these factors on survival. One hundred and ninety cases met the criteria for inclusion in this analysis. A loglinear model was used to identify the patient characteristics associated with a favorable prognosis for survival. These included a performance score of 80-100, colorectal carcinoma primary, and no extrahepatic metastases. A logistic regression equation was derived and confirmed that the probability of surviving at least 6 months depended on the effects of performance score, primary site and the presence or absence of extra-hepatic metastases. Patients with all three favorable factors constituted 30% of the evaluable study population and had a predicted survival of 50% at 6 months. A patient population with these characteristics will be used to study the late effects of accelerated fractionated radiation therapy on the liver.

Retrospective analysis of hyperthermia for use in the palliative treatment of cancer: a multi-modality evaluation.

Forty-two patients with local or superficial metastatic or recurrent malignant tumors were treated in a non-randomized Phase I/II study to assess the tumoricidal effects of heat combined with radiation and/or chemotherapy. Radiation doses administered averaged 3130 +/- 350 cGy; chemotherapeutic agents employed included bleomycin, mitomycin-C, adriamycin, and cis-platin, heat was induced by radiative or interstitial microwave applicators operating at frequencies ranging from 95 to 900 MHz. Forty-one of the forty-two patients were evaluated for initial therapeutic effects yielding the following response distributions: local hyperthermia with radiation--42% complete response (CR), 44% partial response (PR), and 15% no response (NR); local hyperthermia with chemotherapy--0% CR, 50% PR and 50% NR. Long-term response duration was evaluated for local hyperthermia with radiation, yielding mean time to recurrence of 9.4 months for CR's and mean time to progression of 3.4 months for PR's. In retrospective analysis, we examined the correlations of previously established response-predictor variables of tumor volume and minimum thermal dose with both initial and long-term response rates. Initial complete response rates were correlated directly with non-site-specific minimum thermal dose, varied inversely with tumor volume and exhibited a positive correlation for a limited histologic type/treatment site combination. Surprisingly, long-term response did not correlate either with tumor volume or thermal dose. The frequency of thermally induced complications, which did not correlate with any measured thermal parameters, was found to be 42%, expressed on a per-patient basis.

Failure of accelerated neutron therapy to control high grade astrocytomas.

Sixty-two patients with high grade malignant astrocytoma were treated with fast neutrons using three different treatment schemes to evaluate the effect of shortening the overall time. Dose and fraction number were kept constant. The total dose was 16-18 neutron Gy delivered in six fractions, weekly for 6 weeks, twice a week over 3-4 weeks, or three times a week over 2 weeks. There were no obvious differences in survival times among the three groups. We conclude that accelerated neutron therapy does not improve survival of patients with grade 3 and 4 astrocytoma.

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.

Fast neutron radiotherapy for locally advanced prostate cancer. Update of a past trial and future research directions.

Between June, 1977, and April, 1983, the Radiation Therapy Oncology Group (RTOG) sponsored a phase III study comparing fast neutron radiotherapy as part of a mixed beam (neutron/photon) regimen with conventional photon (x-ray) radiotherapy for patients with locally advanced (Stages C and D1) adenocarcinoma of the prostate. A total of 91 analyzable patients were entered into the study with the two treatment groups balanced in regard to all major prognostic variables. The current analysis is for a median follow-up of 6.7 years (range 3.4-9.0 yrs.). The results are statistically significant in favor of the mixed-beam group of all parameters mentioned. At five years the freedom from local/regional relapse rate is 81 percent on the mixed-beam arm compared with 60 percent on the photon arm. The actuarial overall survival rate at five years is 70 percent on the mixed beam compared with 56 percent on the conventional photon arm. The determinantal survival at five years (which excluded death due to intercurrent disease in patients clinically free of cancer) was 82 percent on the mixed-beam arm compared with 61 percent on the photon arm. The type of therapy appeared to be the most important predictor of both local tumor control and patient survival in a step-wise Cox analysis. There was no difference in the treatment-related morbidity for the two patient groups. Mixed-beam therapy may be superior to standard photon radiotherapy for treatment of locally advanced prostate cancer.

Hyperfractionation decreases the deleterious effects of conventional radiation fractionation on vertebral growth in animals.

Craniospinal axis irradiation in the treatment of pediatric tumors is associated with serious long-term sequelae including decreased bone growth (short sitting stature). In this study, an animal model was used to determine the effects of smaller incremental doses of radiation on bone growth. Sprague-Dawley weanling rats were given 25 Gy to the spine in 8 to 9 days, with fraction sizes ranging from 1.0 to 1.8 Gy. The animals receiving smaller doses per fraction (1.0 or 1.25 Gy) showed significantly more growth of the vertebral bodies in the treated fields than animals given larger incremental doses (1.5 or 1.8 Gy). These findings indicate a protective effect on bone growth for hyperfractionated irradiation of vertebral bodies.

Stage I and II non-Hodgkin's lymphomas: long-term results of radiation therapy.

One hundred and sixteen patients with Stages I and II non-Hodgkin's lymphomas were treated with curative radiotherapy between 1964 and 1977. The initial biopsy material was classified according to the criteria of Rappaport et al. All the patients except six were followed for a minimum of 8 years or until death with ninety-two patients having been followed for 10 or more years. Histological pattern was found to be an important prognostic factor with better survival in patients with nodular histology. There were forty-three patients with an initial involvement of an extra-nodal site forming 37% of the total group. Stage I extra-nodal lymphomas had a survival and recurrence-free survival rates of 80% and 74% respectively, similar to those of nodal lymphomas. Stage II patients in both groups did worse than those with Stage I. Survival rates and disease-free survival rates for different histologic types and their pattern of recurrence are presented.

Neutron therapy for nonresectable radioresistant tumors.

Locally advanced, nonresectable, radioresistant tumors can often be ablated by external irradiation using high-energy fast neutron beams. Long-term local control has been achieved in a wide range of malignant tumors, notably sarcomas of bone and soft tissue and adenocarcinomas in various sites. Complete response and long-term remission, with local control rates between 50% and 70%, have been reported in a number of very large osteogenic sarcomas, soft-tissue sarcomas (particularly neurogenic tumors), melanomas, and adenocarcinomas of the alimentary tract. Malignant salivary gland tumors and carcinoma of the prostate appear to be the most responsive to neutrons, with a high frequency (70% to 90%) of successful remission and significantly improved survival even in advanced stages of disease. The biological mechanisms underlying radioresistance of tumor cells and the rationale for using heavily ionizing particles are described. Neutrons are shown to be a valuable adjunct in managing nonresectable malignant tumors that resist conventional therapy.