Association Between Adjuvant Therapy and Survival in Stage II-III Endometrial Cancer: Influence of Malignant Peritoneal Cytology.

OBJECTIVE

The aim of this study was to examine the survival effect of adjuvant therapy in stage II-III endometrial cancer based on peritoneal cytology results.

METHODS

The National Cancer Institute's Surveillance, Epidemiology, and End Results Program was retrospectively queried to examine 7467 women with stage II-III endometrial cancer who underwent hysterectomy, and with available peritoneal cytology results, from 2010 to 2016. A Cox proportional hazard regression model was fitted to assess the association between adjuvant therapy and all-cause mortality stratified by peritoneal cytology results.

RESULTS

Malignant peritoneal cytology was reported in 1662 (22.3%) women and was associated with non-endometrioid histology, higher tumor stage, and nodal metastasis (p < 0.05). In a propensity score-weighted model, malignant peritoneal cytology was associated with increased all-cause mortality compared with negative peritoneal cytology (hazard ratio 1.35, 95% confidence interval 1.23-1.48). Adjuvant therapy types varied based on histology and peritoneal cytology results. In non-endometrioid histology, the combination of chemotherapy and whole pelvic radiotherapy (WPRT) was associated with improved overall survival compared with chemotherapy or WPRT alone irrespective of the peritoneal cytology results (p < 0.05). The combination of chemotherapy and WPRT was also associated with improved overall survival in women with endometrioid histology and malignant peritoneal cytology (p = 0.026). Women with endometrioid histology and negative peritoneal cytology represented the most common subpopulation (46.5%), and overall survival was similar regardless of which of the three adjuvant therapy modalities was used (p = 0.319).

CONCLUSIONS

Malignant peritoneal cytology is prevalent and prognostic in stage II-III endometrial cancer. This study found that the surgeon's choice and benefit of adjuvant therapy for women with stage II-III endometrial cancer differed depending on the status of peritoneal cytology.