Adjuvant radiotherapy for stage I, grade 2 endometrial adenocarcinoma and adenoacanthoma with limited myometrial invasion.

All cases of endometrial adenocarcinoma from January 1970 to December 1980 treated at the Geisinger Medical Center were reviewed retrospectively. One hundred eighty-eight cases of stage I grade 2 adenocarcinoma of favorable histologic subtype (adenocarcinoma, adenoacanthoma) and limited myometrial invasion (less than one-third of the myometrium) were identified. Surgery and adjuvant radiotherapy was used in 136 cases, and 52 cases were treated with surgery alone. There was no statistically significant difference between the two groups in menopausal status, parity, exogenous estrogen, obesity, hypertension, diabetes, or uterine size. Five-year survival for the surgery and radiotherapy group was 94% (128 of 136), and the recurrence rate was 2.2% (three of 136). The five-year survival for the surgery-alone group was 98% (51 of 52), and the recurrence rate was 1.9% (one of 52). There was no statistically significant difference in five-year survival or recurrence between the two groups. This study suggests that surgery alone is adequate treatment for stage I grade 2 adenocarcinoma of favorable histologic subtype and limited myometrial invasion. This study also shows a possible benefit in the combined use of histologic subtype, grade, and myometrial invasion as prognostic indicators and as guides for adjuvant radiotherapy.