The Significance of Tumor Involved Adenomyosis in Otherwise Low-stage Endometrioid Adenocarcinoma

Depth of myometrial invasion by endometrioid adenocarcinoma (EMAC) is one of the most important predictive factors of disease recurrence. It is unclear whether myoinvasion arising in carcinomatous involvement of adenomyosis (AM) changes prognosis. The purpose of this study was to evaluate the significance and frequency of the tumor involved AM in otherwise low-stage cancers. Eighty-two hysterectomies with EMAC with less than 50% myoinvasion (T1a, FIGO IA), AM, and at least 2 years of follow-up information were reviewed. The tumors were divided into 4 histologic groups: group 1, no involvement of AM by EMAC (n=38); group 2, tumor involved AM surrounded by endometrial stroma (n=31); group 3, tumor involved AM with incomplete peripheral endometrial stroma (n=10); and group 4, tumor involved AM with invasion into adjacent smooth muscle (n=3). Tumor involved AM was in the inner half of the myometrium in 35 cases and in the outer half of the myometrium in 9 cases. The only adverse outcome was vaginal recurrence, which was noted in 2 of 82 patients; both the patients were from the control group. None of the patients with deep-seated tumor involved AM had tumor recurrence. In otherwise low-stage tumors, our data support the concept that tumor involvement of the deeply located AM does not affect prognosis. Myometrial-based foci of well-differentiated EMAC, completely or partially surrounded by endometrial stroma, most likely represents tumor colonized AM. Determining invasion out of these foci is subjective, and although limited by rarity in this study, carries no adverse outcome. Therefore, staging should be based on the myoinvasion noted at the native endomyometrial junction.