Ten-year outcome including patterns of failure and toxicity for adjuvant whole abdominopelvic irradiation in high-risk and poor histologic feature patients with endometrial carcinoma.

Purpose: To evaluate the long-term results of treatment using adjuvant whole abdominal irradiation (WAPI) with a pelvic/vaginal boost in patients with Stage I-III endometrial carcinoma at high risk of intra-abdominopelvic recurrence, including clear cell (CC) and serous-papillary (SP) histologic features.

Methods And Materials: In a prospective nonrandomized trial, 119 patients were treated with adjuvant WAPI between November 1981 and April 2000. All patients were analyzed, including those who did not complete therapy. The mean age at diagnosis was 66 years (range 39-88). Thirty-eight patients (32%) had 1989 FIGO Stage I-II disease and 81 (68%) had Stage III. The pathologic features included the following: 64 (54%) with deep myometrial invasion, 48 (40%) with positive peritoneal cytologic findings, 69 (58%) with high-grade lesions, 21 (18%) with positive pelvic/para-aortic lymph nodes, and 44 (37%) with SP or CC histologic findings.

Results: The mean follow-up was 5.8 years (range 0.2-14.7). For the entire group, the 5- and 10-year cause-specific survival (CSS) rate was 75% and 69% and the disease-free survival (DFS) rate was 58% and 48%, respectively. When stratified by histologic features, the 5- and 10-year CSS rate for adenocarcinoma was 76% and 71%, and for serous papillary/CC subtypes, it was 74% and 63%, respectively (p = 0.917). The 5- and 10-year DFS rate for adenocarcinoma was 60% and 50% and was 54% and 37% serous papillary/CC subtypes, respectively (p = 0.498). For surgical Stage I-II, the 5-year CSS rate was 82% for adenocarcinoma and 87% for SP/CC features (p = 0.480). For Stage III, it was 75% and 57%, respectively (p = 0.129). Thirty-seven patients had a relapse, with the first site of failure the abdomen/pelvis in 14 (38%), lung in 8 (22%), extraabdominal lymph nodes in 7 (19%), vagina in 6 (16%), and other in 2 (5%). When stratified by histologic variant, 32% of patients with adenocarcinoma and 30% with the SP/CC subtype developed recurrent disease. Most failures for either histologic group occurred within the abdominopelvic region. However, one-third of the adenocarcinoma recurrences were in the lung. Multivariate regression analysis (age, surgical stage, grade, myometrial invasion, histologic type, lymph node status, and peritoneal cytology) demonstrated age (p = 0.019) and surgical stage (p = 0.036) to be of prognostic significance for CSS; age (p = 0.036) was the only significant prognostic factor for DFS. Grade 1-2 gastrointestinal and hematologic acute toxicities were common. Asymptomatic bibasilar scarring on chest X-ray and mild elevation of liver enzymes were seen in almost 50% of the patients. Even though chronic toxicities were less frequent, 12% developed Grade 3-4 gastrointestinal and 2% Grade 3 renal toxicities.

Conclusion: Adjuvant WAPI is very effective treatment with excellent 10-year results for Stage I-III endometrial carcinoma with risk factors for intra-abdominopelvic recurrence, including SP or CC histologic variants, deep myometrial invasion, high grade, nodal involvement, and positive peritoneal cytology. The low long-term complication rate with high CSS rate makes WAPI the treatment of choice for these patients with significant comorbidities.