Delayed split whole abdominal irradiation in the combined modality treatment of ovarian cancer

Fifty-eight patients with ovarian malignancies have been treated using a delayed split whole abdominal irradiation technique (DSA) allowing the entire tumor volume to be irradiated with tumoricidal fractional doses without undue toxicity. The lower hemiabdomen was irradiated with 2 Gy per fraction to a total dose of 40 Gy. A 2-6 hour delay was used between the irradiation of each half of the abdomen to avoid excessive acute gastrointestinal toxicity. The upper hemiabdomen was irradiated with 1.5 Gy per fraction to a total dose of 30 Gy. The acute toxicity was acceptable, with 53 of 58 patients able to complete the prescribed course of treatment. Three patients (5%) experienced grade 3 or greater acute gastrointestinal toxicity. Fourteen of 60 patients (24%) required treatment breaks because of thrombocytopenia. Nadir platelet counts were lower in patients who had received previous chemotherapy than in previously untreated patients (80,000 vs 118,000; p = .02). However, only 4 out of 60 patients were unable to complete DSA because of prolonged thrombocytopenia. In addition to DSA, patients were also treated with intraperitoneal 32P (52 patients), intraperitoneal human ovarian antitumor serum (14 patients), and prior (14 patients) or subsequent (32 patients) chemotherapy. Granulocytopenia was more severe among patients who had received prior chemotherapy (mean nadir 900 vs 2200). Seven patients (11.5%) developed delayed bowel obstruction in the absence of recurrence. There was one death caused by hepatitis, presumably related to colloidal 32P and DSA. Twenty-five percent of Stage III optimally cytoreduced patients were disease-free at 5 years; these patients had a median survival of 45 months. DSA irradiation is an acceptable technique for delivering a high fractional dose of radiation to the entire peritoneal cavity. Shielding of the iliac crests spares bone marrow allowing DSA irradiation to be integrated into an aggressive combined modality treatment plan.