Malignant Tumors of the Ovary Managed with Postoperative Megavoltage Irradiation

Abstract

The wide range of survival rates given by various authors for ovarian-cancer patients (1, 2) results from several factors. Ovarian cancer encompasses a group of diseases with different biological behavior. There is, furthermore, considerable variation in the histological interpretation of which tumors should be considered true carcinomas. There is still no uniformity of the clinical staging used for reporting results for different treatment modalities. As our knowledge of the complex ovarian structures increases, fundamental tumor types are more clearly defined. In recent decades, chemotherapy has played a greater role in managing ovarian carcinoma; the number of cases referred for postoperative radiation therapy, therefore, has diminished. Clinical Material This paper evaluates the role of postoperative irradiation in treating patients with ovarian cancer and analyzes results obtained with postoperative megavoltage irradiation in a group of 161 patients with ovarian carcinoma treated at the University of Texas M. D. Anderson Hospital and Tumor Institute, Houston, from May 1954 to January 1964. Particular reference to the presence of palpable tumor before postoperative irradiation, treatment technics, and outline of indications for radiotherapy is made. An attempt to study the influence of degree of differentiation was made, but there was no uniformity of criteria in the pathology reports. In this series there is not one case classified as endometrioid carcinoma; endometrioid carcinoma occurred in about 30 per cent of 911 true ovarian carcinomas managed at the Radiumhemmet (3) and in 17 per cent of 120 cases examined by Long and Taylor (4). The prognosis is more favorable for this type of tumor; including some of these tumors in a series, therefore, would affect the overall results. For this study, cases were staged according to stage grouping for primary carcinoma of the ovary recommended by the Cancer Committee of the International Federation of Gynecology and Obstetrics in September 1964 (Table I) (5). To study the significance of palpable and nonpalpable residual tumor before starting postoperative irradiation, we have subdivided Stages II and III according to the presence of palpable disease. Most surgical procedures were done outside this institution; on staging the cases, therefore, we accepted the degree of extension given by the referring physician. This was done only for the papillary serous carcinoma group which was the only group in sufficient numbers. Table II shows that about half the patients treated postoperatively were classified as papillary serous carcinomas. The other half comprises several other histopathological groups in small numbers; therefore, no conclusions can be drawn. Treatment Through the years, different treatment modalities have been used (6). In 12 cases, the pelvis only was irradiated (Fig. 1), mainly with a 22-MeV photon beam; occasionally, a patient was irradiated on the cobalt unit to 4,000 to 6,000 rads.