PORTEC-2 randomized patients with apparent uterine-confined endometrial cancer at high risk for recurrence (>60 years of age with grade 1 or 2, stage IB and grade 3, stage IA; or any age, any grade IIA with <50% myometrial invasion), to pelvic ERT (46 Gy, in 23 fractions) versus vaginal brachytherapy (21 Gy in three HDR fractions or 30 Gy LDR, to a depth of 0.5 cm). At 3 years, there was no difference in vaginal failure rates (0.9% for vaginal brachytherapy, 2% for pelvic ERT; p = .97).There was a higher rate of nonvaginal pelvic relapse in the brachytherapy group (3.6 %) compared to the ERT group (0.7%; p = .03), however, the absolute difference was small and there was no difference in overall survival (292). The difference between nonvaginal pelvic recurrences may be a reﬂection of unrecognized lymph node metastases at the time of initial surgery treated with ERT. One concern regarding PORTEC-2 is that there was not a surgery-only control in the study. However, the highest risk endometrial cancer subgroup in PORTEC-1 (patients >60 years of age with grade 3 or deeply invasive grade 1 or 2, all stage I) was similar to the cohort included in PORTEC-2 and the locoregional recurrence rate in patients who did not receive adjuvant ERT in PORTEC-1 was 18% (135).
Table 35.11 Recurrence in High-Risk, Comprehensively Staged, Early-Stage Endometrial Cancer after Adjuvant Vaginal Brachytherapy Alone (No Pelvic ERT)
ERT, external radiation therapy.
Grade 3 histology and lymphovascular space invasion are proven predictors of vaginal relapse in stage I endometrial cancer. Patients with these risk factors are the most likely group to benefit from vaginal vault brachytherapy (280). Although vaginal recurrences can be successfully treated and controlled in up to 81% of cases,the addition of vaginal brachytherapy to the initial surgical intervention can significantly reduce the risk of such recurrences (293).
External Pelvic Radiation Radiation therapy traditionally was suggested to patients who were deemed to have intermediate or high risk of recurrence, according to grade and depth of myometrial invasion. Several retrospective studies and large, randomized trials did not show an overall survival benefit for intermediate-and high-risk patients with stage I endometrial cancer (or occult IIA endometrial cancer according to the 1988 FIGO staging) who received adjuvant pelvic radiotherapy.