Background
Phase III RCT (GOG protocol 7602). 202 patients with stage I-II epithelial ovarian cancer at high risk of recurrence (stage IB-IIA, grade 2–3 or clear cell; stage IC-IIA any grade; stage IIB-IIC any grade). Randomized to whole abdominal irradiation (WAI) vs intraperitoneal 32-phosphorus (IP 32-P) adjuvant therapy after primary surgery. WAI: 30 Gy to whole abdomen with pelvic boost to 45 Gy. IP 32-P: 15 mCi administered intraperitoneally. Both were standard adjuvant approaches before the platinum chemotherapy era.
Interventions and follow up
Arm A: Whole abdominal irradiation (WAI): 30 Gy to whole abdomen + pelvic boost to 45 Gy
Arm B: Intraperitoneal 32-phosphorus (IP 32-P): 15 mCi IP
Primary endpoint: Recurrence-free survival, OS
mFollow up: 12.5 year
Arm B: Intraperitoneal 32-phosphorus (IP 32-P): 15 mCi IP
Primary endpoint: Recurrence-free survival, OS
mFollow up: 12.5 year
Results
10-year recurrence-free survival: 64% (WAI) vs 67% (IP 32-P) — not significantly different
10-year OS: 68% (WAI) vs 71% (IP 32-P) — not significantly different
Acute bowel toxicity grade ≥3: Higher with WAI (20%) vs IP 32-P (11%)
10-year OS: 68% (WAI) vs 71% (IP 32-P) — not significantly different
Acute bowel toxicity grade ≥3: Higher with WAI (20%) vs IP 32-P (11%)
Adverse events
Main adverse events: Late bowel toxicity (obstruction requiring surgery): 7% (WAI) vs 2% (IP 32-P), P=.03 — significantly higher with WAI. Hematologic toxicity: higher with IP 32-P acutely. Late toxicity overall favored IP 32-P.
Conclusions
WAI and IP 32-P had equivalent efficacy for early-stage high-risk ovarian cancer, but WAI was associated with significantly more late bowel toxicity (obstruction requiring surgery). IP 32-P was preferred on a toxicity basis when choosing between these two modalities.
Key Limitations
Key Limitations: This trial was conducted in the pre-platinum era — neither WAI nor IP 32-P is current standard of care for early ovarian cancer. Carboplatin + paclitaxel chemotherapy has supplanted both modalities. Stage definitions and surgical staging have evolved substantially. The 12.5-year follow-up is a strength but the patient population is no longer representative of current early-stage OC management.
Clinical Context
GOG 7602 has primarily historical value. Adjuvant RT (WAI or IP 32-P) for early ovarian cancer has been replaced by carboplatin-based chemotherapy (GOG 157 carboplatin + paclitaxel × 3 vs 6 cycles). Whole abdominal RT is no longer used as adjuvant therapy. The modern role for RT in ovarian cancer is limited to consolidative treatment of oligometastatic or locoregional recurrence.
References
References: Young RC et al, J Clin Oncol 2003 (GOG 7602)