The current status of drug development of hypoxic cell radiosensitizers and their potential role in gynecologic oncology

Long-Term Survivors Using Intraoperative Radiotherapy for Recurrent Gynecologic Malignancies

PURPOSE

To analyze the outcomes of therapy and identify prognostic factors for patients treated with surgery followed by intraoperative radiotherapy (IORT) for gynecologic malignancies at a single institution.

METHODS AND MATERIALS

We performed a retrospective review of 36 consecutive patients treated with IORT to 44 sites with mean follow-up of 50 months. The primary site was the cervix in 47%, endometrium in 31%, vulva in 14%, vagina in 6%, and fallopian tubes in 3%. Previous RT had failed in 72% of patients, and 89% had recurrent disease. Of 38 IORT sessions, 84% included maximal cytoreductive surgery, including 18% exenterations. The mean age was 52 years (range, 30-74), mean tumor size was 5 cm (range, 0.5-12), previous disease-free interval was 32 months (range, 0-177), and mean IORT dose was 1,152 cGy (range, 600-1,750). RT and systemic therapy after IORT were given to 53% and 24% of the cohort, respectively. The outcomes measured were locoregional control (LRC), distant metastasis-free survival (DMFS), disease-specific survival (DSS), and treatment-related complications.

RESULTS

The Kaplan-Meier 5-year LRC, DMFS, and DSS probability for the whole group was 44%, 51%, and 47%, respectively. For cervical cancer patients, the Kaplan-Meier 5-year LRC, DMFS, and DSS estimate was 45%, 60%, and 46%, respectively. The prognostic factors found on multivariate analysis (p <or= 0.05) were the disease-free interval for LRC, tumor size for DMFS, and cervical primary, previous surgery, and locoregional relapse for DSS. Our cohort had 10 Grade 3-4 complications associated with treatment (surgery and IORT) and a Kaplan-Meier 5-year Grade 3-4 complication-free survival rate of 72%.

CONCLUSIONS

Survival for pelvic recurrence of gynecologic cancer is poor (range, 0-25%). IORT after surgery seems to confer long-term local control in carefully selected patients.

Primary carcinoma of the vagina: Tata Memorial Hospital experience

PURPOSE

Carcinoma of the vagina is a rare gynecological malignancy comprising approximately 2% of all the gynecological malignancies. We have analyzed the treatment outcome of the patients treated at the Tata Memorial Hospital from January 1984 to December 1993.

METHODS AND MATERIALS

In this 10-year period, 134 patients of primary vaginal cancers were registered at our hospital. Of these, 75 patients received complete treatment and are analyzed.

RESULTS

Disease-free survival (DFS) for the whole group is 50%, and overall survival (OAS) is 60%. Most locoregional recurrences and distant failures are noted in the 2 years following treatment. DFS at 5 years is as follows: Stage I (5 patients), Stage IIA (37 patients), Stage IIB (15 patients), Stage III (14 patients), and Stage IV (4 patients); are 40%, 55%, 60%, 50%, and 25%, respectively. The DFS for patients with complete response (42 patients) to external radiation at 5 years is 68%, with partial response (25 patients) is 35%, and with poor or no response (6 patients) is 18% (p = 0.0000). We observed that brachytherapy was an important part of the treatment, and patients who received brachytherapy (59 patients), either with a vaginal intracavitary applicator (30 patients) or interstitial implant (29 patients) had a DFS of 53% and 56%, respectively, while 15 patients who received external radiation alone had a DFS of 30%. Patients receiving brachytherapy within 4 weeks of external radiation had a DFS of 60% as compared to 30% when the interval was more than 4 weeks.

CONCLUSION

The factors indicating prognosis are: site and extent of involvement, presence of lymph nodes at presentation, technique of brachytherapy, and interval between external radiation and brachytherapy.

Radiation therapy for primary squamous cell carcinoma of the vagina: Stanford University experience

A retrospective analysis of 38 patients with primary squamous cell carcinoma of the vagina seen at Stanford University Medical Center from 1958 to 1984 was undertaken. Patients were analyzed with regard to symptoms, stage, treatment techniques, survival, patterns of failure, and complications. Eighteen patients were classified as FIGO Stage I, 5 as Stage II, 10 as Stage III, and 5 as Stage IV. The 5-year disease-free survival was 94% in Stage I, 80% in Stage II, 50% in Stage III, and 0% in Stage IV. Five patients (13%) had eight major complications secondary to treatment. Only 2 of 23 patients with Stage I or Stage II disease developed a recurrence. There was a significant correlation between dose and response in patients treated with radiotherapy.

Radiotherapy with or without misonidazole for patients with stage IIIB or stage IVA squamous cell carcinoma of the uterine cervix: preliminary report of a Radiation Therapy Oncology Group randomized trial

Between August 1980 and November 1984, 119 patients with FIGO Stage IIIB or IVA squamous cell carcinoma of the uterine cervix were randomized to receive radiation therapy (4600 cGy pelvis plus 1000 cGy parametrial boost) followed by intracavitary or external boost to the primary with or without misonidazole (MISO) (400 mg/m2 daily 2 to 4 hours prior to radiation therapy). Patients in the two treatment groups were evenly distributed with respect to stratification variables including stage, Karnofsky Performance score, and positivity of para-aortic nodes. Eighty-nine percent of patients had Stage IIIB disease and 88% had a Karnofsky score of 80 or better. Seventy-five percent of patients treated with radiation therapy alone and 79% of patients treated with radiation therapy plus MISO received a boost via intracavitary application. Life threatening (Grade 4) complications occurred in 5 patients receiving radiation therapy alone and one patient receiving radiation therapy plus MISO. MISO toxicity (Grade 3) was limited to severe nausea and vomiting in two patients. With 119 evaluable patients and a median follow-up of 33 months, 64% of patients receiving radiation therapy alone are alive at 18 months compared with 54% for patients assigned to radiation therapy plus MISO. The median survival for patients treated with radiation therapy alone and radiation therapy plus MISO was 1.9 years and 1.6 respectively. At this point in the study the difference in survival is inconsistent with the hypothesis of an improvement associated with MISO. There have been 23 deaths among the 49 patients treated with radiation therapy plus MISO who have been followed for at least 18 months compared with 17 deaths in 48 patients treated with radiation therapy alone. The chance of observing this number of deaths with radiation therapy plus MISO if the addition of MISO improves survival by 10 to 20% is 0.003 and less than 0.001, respectively. The addition of MISO to radiation failed to improve survival for these patients. The results cannot be explained by an uncharacteristically high survival on the radiation therapy alone arm or by an imbalance in the distribution of prognostic factors. Local-regional control remains a problem in the management of patients with advanced cervical carcinoma. More effective and less toxic radiosensitizing agents are needed.

Direct effects of the hypoxic cell sensitizer misonidazole on colony formation in a human tumor cloning assay

The human tumor cloning assay as described by Hamburger and Salmon was utilized to study the direct antitumor effects of the hypoxic cell sensitizer misonidazole (MISO). Cells from 106 tumor specimens directly obtained from patients were exposed to MISO at clinically achievable drug concentrations (0.5 mM). Of 30 evaluable tumors, seven specimens (23%) showed a less than or equal to 50% decrease of TCFU's. In vitro sensitivity to MISO was noted in human breast cancer, renal cancer, non small-cell lung cancer, and adenocarcinoma of unknown primary site. A dose response relationship was demonstrated in a subset of experiments including 6 patient's tumors and one human breast cancer cell-line. An analysis relating MISO sensitivity or resistance to the results obtained with other, simultaneously tested standard anticancer drugs indicated that tumors exhibiting a less than or equal to 50% decrease of TCFU's in the presence of MISO were also likely to be sensitive to other cytotoxic drugs. In summary, our data suggest that the 'nitroimidazoles' may exert clinically significant direct antitumor effects in individual tumors. The human tumor cloning assay may have potential to evaluate these direct effects of MISO-analogues and other new radiosensitizers currently being tested in clinical trials.