Whole abdominal irradiation following chemotherapy in patients with minimal residual disease after second look surgery in ovarian carcinoma

Release of Interferon-β (IFN-β) from Probiotic Limosilactobacillus reuteri-IFN-β (LR-IFN-β) Mitigates Gastrointestinal Acute Radiation Syndrome (GI-ARS) following Whole Abdominal Irradiation

Irradiation can be an effective treatment for ovarian cancer, but its use is limited by intestinal toxicity. Thus, strategies to mitigate toxicity are important and can revitalize the current standard of care. We previously established that LR-IL-22 protects the intestine from WAI. We now hypothesize that LR-IFN-β is an effective radiation protector and mitigator and is rapidly cleared from the digestive tract, making it an option for intestinal radioprotection. We report that the gavage of LR-IFN-β during WAI provides improved intestinal barrier integrity and significantly preserves the numbers of Lgr5+GFP+ intestinal stem cells, improving survival. The rapid clearance of the genetically engineered probiotic from the digestive tract renders it a safe and feasible radiation mitigator. Therefore, the above genetically engineered probiotic is both a feasible and effective radiation mitigator that could potentially revolutionize the management of OC patients. Furthermore, the subsequent addition of platinum/taxane-based chemotherapy to the combination of WAI and LR-IFN-β should reduce tumor volume while protecting the intestine and should improve the overall survival in OC patients.

Lactobacillus reuteri Releasing IL-22 (LR-IL-22) Facilitates Intestinal Radioprotection for Whole-Abdomen Irradiation (WAI) of Ovarian Cancer

Oral administration (gavage) of a second-generation probiotic, Lactobacillus reuteri (L. reuteri), that releases interleukin-22 (LR-IL-22) at 24 h after total-body irradiation (TBI) mitigates damage to the intestine. We determined that LR-IL-22 also mitigates partial-body irradiation (PBI) and whole-abdomen irradiation (WAI). Irradiation can be an effective treatment for ovarian cancer, but its use is limited by intestinal toxicity. Strategies to mitigate toxicity are important and can revitalize this modality to treat ovarian cancer. In the present studies, we evaluated whether LR-IL-22 facilitates fractionated WAI in female C57BL/6 mice with disseminated ovarian cancer given a single fraction of either 15.75 Gy or 19.75 Gy or 4 daily fractions of 6 Gy or 6.5 Gy. Mice receiving single or multiple administrations of LR-IL-22 during WAI showed improved intestinal barrier integrity (P = 0.0167), reduced levels of radiation-induced intestinal cytokines including KC/CXCL1 (P = 0.002) and IFN-γ (P = 0.0024), and reduced levels of plasma, Eotaxin/CCL11 (P = 0.0088). LR-IL-22 significantly preserved the numbers of Lgr5+GFP+ intestinal stem cells (P = 0.0010) and improved survival (P < 0.0343). Female C57BL/6MUC-1 mice with widespread abdominal syngeneic 2F8cis ovarian cancer that received LR-IL-22 during 6.5 Gy WAI in 4 fractions had reduced tumor burden, less intestinal toxicity, and improved 30-day survival. Furthermore, LR-IL-22 facilitated WAI when added to Paclitaxel and Carboplatin chemotherapy and further increased survival. Oral administration (gavage) of LR-IL-22 is a potentially valuable intestinal radioprotector, which can facilitate therapeutic WAI for widespread intra-abdominal ovarian cancer.

Novel Therapeutic Strategies for Ovarian Cancer Stem Cells

Ovarian cancer (OC) is one of the most lethal gynecologic malignancies. Due to the lack of specific symptoms and screening methods, this disease is usually diagnosed only at an advanced and metastatic stage. The gold-standard treatment for OC patients consists of debulking surgery followed by taxane combined with platinum-based chemotherapy. Most patients show complete clinical remission after first-line therapy, but the majority of them ultimately relapse, developing radio- and chemoresistant tumors. It is now proposed that the cause of recurrence and reduced therapy efficacy is the presence of small populations of cancer stem cells (CSCs). These cells are usually resistant against conventional cancer therapies and for this reason, effective targeted therapies for the complete eradication of CSCs are urgently needed. In this review article, we highlight the mechanisms of CSC therapy resistance, epithelial-to-mesenchymal transition, stemness, and novel therapeutic strategies for ovarian CSCs.

Radiation Treatment in Women with Ovarian Cancer: Past, Present, and Future

Ovarian cancer is the most lethal of the gynecologic cancers, with 5-year survival rates less than 50%. Most women present with advanced stage disease as the pattern of spread is typically with dissemination of malignancy throughout the peritoneal cavity prior to development of any symptoms. Prior to the advent of platinum-based chemotherapy, radiotherapy was used as adjuvant therapy to sterilize micrometastatic disease. The evolution of radiotherapy is detailed in this review, which establishes radiotherapy as an effective therapy for women with micrometastatic disease in the peritoneal cavity after surgery, ovarian clear cell carcinoma, focal metastatic disease, and for palliation of advanced disease. However, with older techniques, the toxicity of whole abdominal radiotherapy and the advancement of systemic therapies have limited the use of radiotherapy in this disease. With newer radiotherapy techniques, including intensity-modulated radiotherapy (IMRT), stereotactic body radiotherapy (SBRT), and low-dose hyperfractionation in combination with targeted agents, radiotherapy could be reconsidered as part of the standard management for this deadly disease.

Salvage whole-abdominal radiation therapy after second-look laparotomy or secondary debulking surgery in patients with ovarian cancer

OBJECTIVES

Our aim was to determine the outcomes associated with use of whole-abdominal radiation therapy (WART) in women with ovarian cancer, to identify predictors of response, and to assess associated toxicity.

METHODS

From 1981 through 2000, 171 women received WART at our institution after ovarian cancer surgery. Relevant clinical information was extracted through retrospective chart review.

RESULTS

One hundred nine patients received WART after positive second-look laparotomy (SLL), and 62 were treated after secondary debulking (SD) for recurrent disease. The median dose to the whole abdomen was 25.5 Gy (range, 1.0-30.5 Gy). Therapy included a pelvic boost in 120 patients (70%) and a para-aortic boost in 21 patients (12%). The planned radiation course was completed in 123 patients (72%). In the SLL group, 5-year survival was 29% with a median follow-up of 98.4 months. The 5-year progression-free survival (PFS) was 41% in those with microscopic disease. There was one treatment-related death (1%). For the SD group, median PFS was 11 months and associated with treatment-related mortality in 5%. Overall, treatment-related small bowel obstruction occurred in 26 patients (15%).

CONCLUSIONS

In patients with a positive SLL, WART should be considered only for those with microscopic residual disease. Treatment-related small bowel obstruction can be expected in 15% of these patients. Use of WART for recurrent disease appears to be related to serious bowel toxicity in 5% with an associated short disease-free interval; the therapeutic index of WART may not be acceptable in patients with recurrent disease regardless of the degree of cytoreduction.

Is there place for radiotherapy in the treatment of advanced ovarian cancer?

BACKGROUND AND PURPOSE

Irradiation of advanced ovarian cancer has been performed during the years 1976-1984 with six-field technique. Results of this treatment in a long follow-up have never before been evaluated.

MATERIAL AND METHODS

Seventy-five patients with stage IIb-IV of invasive ovarian cancer have been treated with a combination of surgery, radiotherapy and chemotherapy. The results of the treatment were compared with 98 patients treated during the year 1991-1992 with surgery and chemotherapy only.

RESULTS

After controlling for the differences in background factors between the groups considered, there was still a significantly better survival rate for the patients treated with radiotherapy.

CONCLUSION

The results suggest that the role of radiotherapy in advanced ovarian cancer should be investigated in a prospective randomized trial.

Ovarian cancer

This synthesis of the literature on radiotherapy for cancer originating in the ovaries is based on 74 scientific articles, including 12 randomized studies, 18 prospective studies, and 36 retrospective studies. These studies involve 6,140 patients. Treatment for patients at early stages of ovarian cancer (stages I and II) is surgery. The value of adjuvant treatment, ie, chemotherapy or radiotherapy, is not demonstrated. Tumor volume is decisive to the success of radiotherapy. Microscopic or small macroscopic cancer residuals, remaining after surgery, may respond to radiotherapy, thereby promoting survival. The importance of radiotherapy for advanced ovarian cancer is controversial, and studies frequently show contradictory results. Two studies have shown the favorable role played by radiotherapy in consolidation treatment of patients if they become cancer-free at advanced stages. The role of radiotherapy in treating larger volumes of residual cancer has not been demonstrated, except for strictly palliative treatment.

Abdomino pelvic irradiation after second-look laparotomy for stage III ovarian carcinoma

OBJECTIVE

The purpose of this retrospective analysis of 34 patients with stage III ovarian carcinoma was to review results and morbidity of whole abdominal irradiation after surgery and chemotherapy.

METHODS AND MATERIALS

All of the 34 patients had reached a complete clinical remission after first cytoreductive surgery and chemotherapy. After second-look laparotomy each patient underwent whole abdominal irradiation. Except for two patients with chronic myelosuppression, the dose administered was of 22.5 Gy to the abdominal cavity with a boost of 22.5 Gy added to the pelvis.

RESULTS

Three and 5-year overall survival rates were 62% and 43%, respectively. Three and 5-year disease-free survival rates were 53% and 38%. Twenty-three patients (68%) developed local relapse or local disease progression. Metastasis occurred in five cases and were always associated with an abdominal cavity recurrence. Residual disease after first cytoreductive surgery appeared as a prognostic factor in univariate analysis. Patients with unresected residuum had a 5-year survival probability of 35% versus 83% for patients without residual disease. We observed 12% grade-3 intestinal toxicities and one fatal case of radiation enteritis.

CONCLUSION

Despite its curative potential, the long term benefit of whole abdominal irradiation in the multimodality treatment of advanced ovarian carcinoma must be evaluated in well designed controlled trials.

Evaluation of whole abdominal irradiation in ovarian carcinoma with a four orthogonal fields technique

PURPOSE

The purpose of this study is to evaluate the toxicity and the results of abdominopelvic irradiation with a four orthogonal field's technique in patients with ovarian carcinoma.

METHODS AND MATERIALS

Between May 1981 and December 1990, 167 patients with ovarian carcinoma have been treated with whole abdominal irradiation: 62 patients with no or minimal residual disease < 2 cm after initial surgery (group 1) and 105 patients with no residual disease or macroscopic residual disease < 2 cm assessed by second-look surgery after incomplete debulking surgery and cisplatin-based polychemotherapy (group 2). Irradiation was performed by a four orthogonal field's technique. Thirty grays were given with a 25 MV photon beam (1.5 Gy/fraction/day, 20 fractions over 30 days). Boosts were performed in 50 cases (median dose of 15 Gy).

RESULTS

With a median follow-up of 68 months, the 5-year actuarial survival rate was 50% in the entire group, 67% in group 1, 40% in group 2, and 84% in T1, 61.5% in T2, 38% in T3. Five-year actuarial survival was analyzed according to the residuum: (a) after initial surgery (no residual disease: 70%, residual disease: 36.5%), (b) after second-look surgery: 76% in patients with a negative second look, 66% in patients with microscopic residual disease, 22% in patients with macroscopic residual disease and secondary surgical reduction, and 10% in patients with small unresectable nodules. Nine percent of the patients failed to complete irradiation acute side effects related. Five percent required surgery for bowel obstruction.

CONCLUSION

The abdominopelvic irradiation with this four orthogonal field's technique was associated with tolerable acute toxicity and a low risk of serious late complications. Similar late results to have been reported whole abdominal irradiation with chemotherapy in patients with negative or microscopic residual disease after surgery. Randomized trials comparing these two adjuvant treatments are warranted.

Role of radiotherapy in the treatment of cancer of the ovary

The initial management of carcinoma of the ovary is surgical. The need for further treatment is determined by a consideration of tumor stage, grade, and the presence of residual disease. Approximately one-third of patients are suitably managed by primary post-operative radiotherapy directed to the entire abdomen and pelvis with curative intent. Patients are mainly derived from stages I and II. Stage III patients are also included if the tumor is of low grade and there is no pelvic residuum. The dose which can be safely delivered to the upper abdomen is limited by normal tissue tolerance. Curative radiation is inappropriate for patients with upper abdominal disease and/or more than small volume residuum in the pelvis. These patients are best managed with chemotherapy. Suitably selected patients have a ten-year relapse-free survival of 68% following radiotherapy. Acute gastrointestinal symptoms are common during the treatment, but are usually amenable to symptomatic management. Long term morbidity is infrequent, and with modern techniques the incidence of treatment-related small bowel obstruction is around 5%. Radiotherapy to the abdomen and pelvis has also a potential role as consolidative treatment in patients with advanced disease, following a favourable response to chemotherapy.

Radiotoxic model for three-dimensional treatment planning. Part 1: Theoretical basis

Since recent treatment planning systems calculate volumetric dose distribution, an objective evaluation of potential toxicity in the main critical organs may be helpful in treatment optimization. Modeling the toxicity of radiotherapy must at least account for: (a) specific risks in every critical organ; (b) total dose and dose per fraction; (c) partial irradiation of critical organs; (d) heterogeneous dose distribution. The Radiation Damage Factor formula is aimed at estimating the delayed toxicity of a given treatment plan on every critical organ concerned. The formulation uses a double exponential function: RDF = 100 e-Ke-(a+bd)DVc, where: D is the total dose, and d the dose per fraction; a and b are coefficients representing the radiosensitivity of the critical organ, according to the linear-quadratic model, with a/b = alpha/beta. K represents the theoretical critical unit content of the organ, these critical units being groups of functionally related stem cells. The avoidance of a complication depends on the ability of surviving critical units to preserve organ function. V is the ratio:irradiated volume/total volume of the organ. Exponent c accounts for tissue organization: c is equal to or near 1 in "parallel organs" like the liver or the lung, where localized hot spots are tolerated; c is lower in "series organs" like the spinal cord where hot spots, even in a small portion, are dangerous. Heterogeneous irradiation, summarized by dose cumulative-volume histograms, is accounted for by calculating step by step the dose D' considered as having an equivalent effect when given in the largest irradiated volume ratio. Preliminary calibration of the RDF formula is attempted for radiation myelitis and radiation hepatitis.

Integrating radiation therapy into the management of ovarian cancer

Several studies during the last 15 years have elucidated the role of postoperative external beam radiation therapy as curative management of some subsets of patients with ovarian cancer. Despite this, the use of radiation therapy in patients with ovarian cancer has remained a controversial subject. Substantially improved cure rates have not been realized during the past decade despite the early promise of high response rates to cisplatin chemotherapy. Thus, it is important that all currently effective therapies be used for maximum therapeutic gain. This article will review the evidence that radiation therapy is curative in ovarian cancer and highlight the criteria, including stage and grade of disease and tumor residuum, by which patients suitable for such therapy are selected. The rationale for the use of whole abdominopelvic irradiation rather than pelvic or lower abdominal treatment will be discussed, as will the optimal radiation technique and its attendant morbidity. Limited data pertinent to the controversy over the use of radiation therapy versus chemotherapy in early disease, will be reviewed. The possible benefits of consolidation abdominopelvic radiation therapy after chemotherapy in highly selected patients with well-differentiated microscopic residual disease at second-look laparotomy or with no residual disease but high a risk for relapse will be considered.

Complications of whole abdominal and pelvic radiotherapy following chemotherapy for advanced ovarian cancer

We examined the records of 105 patients with advanced ovarian cancer who had been treated with cisplatin combination chemotherapy followed by abdominopelvic radiotherapy. The purpose was to define the morbidity of this approach, and identify those factors predictive of toxicity. Acute toxicity resulting in delay or failure to complete treatment was most commonly due to myelosuppression. Nine of 105 patients (8.6%) required surgery for bowel obstruction that was not due to recurrent disease, 3 had an episode of bowel obstruction that settled conservatively, and a further 5 underwent surgery for obstruction due to recurrent tumor. The presence of both a dose of abdominopelvic radiotherapy over 2250 cGy, as well as a second-look laparotomy prior to radiotherapy, was associated with an increased risk of serious bowel complications. The increased frequency of late bowel morbidity seen in the combined modality group is likely explained by the presence of these two factors, rather than the exposure to chemotherapeutic agents per se. These observations are supported by the published literature.

Epithelial ovarian cancer: the role of radiotherapy

Although several studies during the last 10-15 years have served to clarify the role of postoperative external beam radiotherapy in patients with ovarian cancer, the subject remains controversial. This paper will review the following topics: 1. Stage I Ovarian Cancer. 2. The rationale for selecting whole abdominopelvic radiotherapy over other forms of radiotherapy, such as pelvic or lower abdominal radiotherapy. 3. The choice of radiation technique. 4. The evidence that radiotherapy is curative in ovarian cancer. 5. The toxicity of abdominopelvic radiotherapy. 6. The criteria by which patients are selected for abdominopelvic radiotherapy. 7. Radiotherapy versus chemotherapy in early disease. 8. Consolidation radiotherapy after chemotherapy in advanced disease.

Whole abdomen radiation therapy after a short chemotherapy course and second-look laparotomy in advanced ovarian cancer

From April 1983 through December 1989, 42 consecutive patients with diagnosis of epithelial ovarian carcinoma were initially managed by aggressive surgery and three courses of endoperitoneal cis-platinum-based chemotherapy followed by an alternating combination chemotherapy and second-look laparotomy. Patients with residual tumor less than or equal to 2 cm subsequently received whole abdominal radiation therapy (WAR). Twenty-eight patients (42% with no residual disease, 21% with microscopic disease, and 36% with residual disease less than 2 cm) were eligible for WAR. WAR was delivered using an open-field technique up to 22 Gy in 20 fractions followed by a pelvic boost of 18 Gy in 10 fractions. The kidneys were shielded posteriorly at 1100 cGy; hepatic shields were not added. One patient did not complete WAR for lung metastases after 5 radiotherapy fractions. The complete treatment program lasted 8 months (range, 6.8-11). The median follow-up of the 28 patients entered into the study was 50 months. Eight patients are alive and disease-free at 5 years. The overall and disease-free survival rates at 5 years are 45 and 30%, respectively. All but 2 patients relapsed within the abdominopelvic cavity and 3 developed brain metastases. Toxic effects, during WAR, required treatment interruption in all but 4 patients: 3 developed a small bowel obstruction requiring surgery and 1 died of surgical complications in complete remission. The poor disease-free survival and the severe toxicity encountered have been valid indications that WAR should be discontinued as a treatment modality in advanced ovarian cancer at our department.

A Role for Tumor Markers in Therapeutic Decisions after Chemotherapy Induction of Objective Remission in Stage III Epithelial Ovarian Neoplasms

The management of advanced stage ovarian carcinomas is presently based on initial surgical debulking, multiple drug chemotherapy including cisplatinum, second-look laparotomy. Such an aggressive approach has improved objective response rates and expected survival time, but no dramatic change has been demonstrated as for definitive cure percentages. Many Authors have attempted to turn an optimal objective response to chemotherapy (no residual or minimal residual disease at second-look) into a definitive cure with irradiation. Some reports show satisfactory results, but a high incidence of bowel obstructive complications has been demonstrated, probably due to multiple surgical manipulations before radiotherapy. A reliable diagnostic tool, that could help to avoid the second-look laparotomy (whose inherent role in improving survival is not assessed) should be therefore useful. The possible role of serum tumor markers determinations, for this purpose, is here discussed on the ground of a series of 20 patients affected by stage III ovarian carcinoma. Following this experience, a valuable role seems attributable to CA 125 in monitoring tumor response. Patients achieving values under 35 U/ml before second-look laparotomy showed tumor residuals in the range O-microscopic- < 1cm., that is, neoplastic localizations reliable for consolidation radiation therapy.

Outcome of patients with unfavorable optimally cytoreduced ovarian cancer treated with chemotherapy and whole abdominal radiation

There is a subgroup of patients with Stage II or III ovarian cancer whose survival is poor despite optimal cytoreduction of tumor and abdominopelvic radiation. This study examined whether the survival of these patients, who have tumor with unfavorable histopathological characteristics and/or small residual disease, could be improved by giving chemotherapy before radiation. Forty-four out of fifty-one eligible patients, seen between 1981 and 1985, with Stage II or III disease were entered into the study. Following six courses of cisplatin-based chemotherapy, 33 (75%) received abdominopelvic radiotherapy. Survival was compared to that of 48 eligible matched control patients, treated with radiation between 1978 and 1981. The median follow-up is 6.6 years. The median survival was extended from 2.4 to 5.7 years (P = 0.13), and 42.6% of patients receiving combined therapy were free of relapse at 5 years, compared to 21.6% (P = 0.03) in the historical control group, treated with abdominopelvic irradiation alone. Only 2 of 44 patients in the combined group required surgery for bowel obstruction, as did 1 of 48 in the control group. Tolerance and toxicity of the combined approach were acceptable. Although we cannot be certain that the entire benefit we observed was not attributable to the chemotherapy alone, there is evidence that the radiotherapy may have been additive. Chemotherapy followed by abdominopelvic radiotherapy seems a reasonable management policy in these patients.

Radiation therapy in stage III ovarian cancer following surgery and chemotherapy: prognostic factors, patterns of relapse, and toxicity: a preliminary report

Twenty patients with FIGO stage III epithelial ovarian cancer who had undergone maximum cytoreductive surgery (including pelvic and paraaortic lymph node dissection) and combination chemotherapy (4-10 cycles, median 6) were treated with irradiation to the abdomen and pelvis with 30 Gy followed by diaphragmatic/paraaortic and pelvis boost fields to 42 and 51.6 Gy, respectively. Second-look laparotomy was not performed. Seventeen of 20 patients completed the planned course of radiation. In 2 cases, failure to complete treatment was related to acute hematologic toxicity, and 1 patient refused further treatment. Five patients (29%) required treatment breaks ranging from 8 to 16 days (median, 12 days) due to pancytopenia. Actuarial overall survival and relapse-free survival at 3 years for the 17 patients who completed radiation was 69 and 47%, respectively, with follow-up ranging from 19 to 53 months (median: 24, mean: 27.6 months). Seven patients (41%) relapsed within the abdomen alone and 2 patients developed extraabdominal lymph node metastasis as their sole site of failure. The prognostic factors evaluated for correlation with relapse-free survival included histologic subtype, grade, amount of residual disease at the time of surgery, and nodal involvement; only residual tumor at surgery (none vs less than or equal to 2 cm or greater than 2 cm) was found to be statistically significant (P less than 0.01). Three-year overall survival correlated with amount of residual disease following the initial cytoreductive surgery. It was 100% for patients with no residual disease, 66.7% for less than or equal to 2 cm, and 26.7% for those with greater than 2 cm residual disease, respectively. Radiation treatment was well tolerated, with only one patient developing treatment-related bowel obstruction 7 months after radiation therapy. The results of this planned trimodality treatment approach compare favorably with those reported following surgery and chemotherapy, particularly in patients who have been maximally cytoreduced.

Curative radiotherapy for laparotomy-staged IA, IIA, IIIA Hodgkin's disease: an evaluation of the gains achieved with radical radiotherapy

Between 1970 and 1983, 179 patients with pathologically staged IA, IIA, and IIIA Hodgkin's disease were treated with curative radiotherapy. From 1970 to 1974, patients were treated with standard extended or total nodal field irradiation (Treatment Group 1). Since 1975, because of the high prevalence of recurrences in patients with large mediastinal mass and/or hilar disease and/or splenic involvement (LMM &/or H+ &/or S+), treatment was modified to include low-dose lung irradiation within the mantle field for those patients with LMM &/or H+ and low-dose liver irradiation within the infradiaphragmatic field for patients with S+ (radical XRT). Patients who did not have those characteristics were treated with standard radiotherapy (standard XRT). A total of 122 patients were treated from 1975 to 1983 (Treatment Group 2), of whom 61 received radical XRT and 61 received standard XRT. An analysis was done to evaluate whether the progressive-improvement in outcome since 1970 at the University of Minnesota Hospital resulted from the contribution of modified treatment or from progressive improvement in treatment overall. There was a statistical improvement in recurrence-free survival (RFS) in Treatment Group 2 (Tr Gr 2) compared to Treatment Group 1 (Tr Gr 1), with 10-year RFS of 80% versus 57% (p less than 0.001 for time to event). The improvement in RFS was attributed to treatment modification consisting of radical XRT for those patients with LMM &/or S+. There was no change in RFS for those patients without LMM &/or H+ &/or S+ who were treated in Tr Gr 1 and Tr Gr 2, with 10-year RFS of 78% versus 86% (p = 0.29), respectively. However, treatment results for patients with LMM &/or H+ &/or S+ improved considerably in the radical XRT group. Comparing standard versus radical XRT, 10-year RFS was 36% versus 78% (p = 0.001), and 10-year OS was 72% versus 92% (p = 0.034). Patterns of relapse also changed for patients with LMM &/or H+ &/or S+ who were treated with radical XRT. Rather than showing a high frequency of intrathoracic recurrence as was seen in those patients with LMM &/or H+ &/or S+ after standard XRT, the relapse pattern was similar to patients without LMM &/or H+ &/or S+. Salvage treatment was well tolerated for patients who failed after radical XRT. Delayed, life-threatening effects, such as pulmonary and cardiovascular complications and SMN, were equivalent for patients in Tr Gr 1 versus 2, and for those who received standard and radical XRT.(ABSTRACT TRUNCATED AT 400 WORDS)

Melphalan resistant human ovarian tumour cells are cross-resistant to photons, but not to high LET neutrons

High linear energy transfer (LET) fast neutrons for the local control of advanced head and neck tumours are currently being evaluated at several centres. Fast neutrons are believed to produce more direct, and less OH mediated damage than photons, and consequently be less affected by intracellular thiol levels. Chemoresistant tumours with elevated thiol levels may therefore be more effectively controlled by fast neutron therapy than by photons. The "in vitro" radiation response of melphalan sensitive and resistant human ovarian tumour cell lines has demonstrated that melphalan resistance confers a 1.5-fold level of cross-resistance to photons, primarily attributable to a 2-fold decrease in the alpha component in the resistant OAW42/MER cell line. Pretreatment of the melphalan-resistant line with the thiol depleting agent buthionine sulphoximine (BSO) restored the magnitude of alpha to a value similar to that in the chemosensitive cell line. The survival curves of these cell lines following neutron irradiation were near exponential, with similar values of alpha. This study has demonstrated that melphalan resistant tumour cells are cross-resistant to photon irradiation, but not to fast neutrons. The mechanism of cross-resistance has yet to be determined, but glutathione (GSH) appears to be involved.