Effect of coexisting adenomyosis on tumour characteristics and prognosis of endometrial cancer: A systematic review and meta-analysis.

To compare clinicopathological features and survival outcomes in patients with endometrial cancer, with and without associated adenomyosis. PubMed, Embase and Scopus databases were systematically searched for relevant observational studies. The pooled effect sizes were reported as either hazards ratio (HR) for survival-related outcomes or as odds ratio (OR) for other categorical outcomes. Weighted mean difference (WMD) was reported for continuous outcomes. All the analyses used the random effects model. A total of 21 studies (N = 46,420) were included. Compared to endometrial cancer patients without adenomyosis, patients with associated adenomyosis had improved overall 5-year survival (OS) (HR 0.62, 95% CI: 0.50, 0.79) and disease-free survival (DFS) (HR 0.60, 95% CI: 0.44, 0.82). Disease-specific survival was statistically similar in patients with and without adenomyosis (HR 0.60, 95% CI: 0.35, 1.05). Among patients with adenomyosis, the risk of having an advanced tumour grade (Grade 2 or 3) was lower (OR 0.51, 95% CI: 0.42, 0.62) and a risk of having International Federation of Gynaecology and Obstetrics (FIGO) stage I or II was higher (OR 2.23, 95% CI: 1.65, 3.01). Patients with adenomyosis had lower risk of tumour invasion of adnexa, cervical stromal invasion, deep myometrial involvement (DMI), lympho-vascular space invasion (LVSI) and peritoneal invasion. Presence of adenomyosis in patients with endometrial cancer is associated with favourable tumour characteristics and may improve the survival.