Significance of abnormal peritoneal cytology on survival of women with stage I-II endometrioid endometrial cancer

Objective: To examine survival of women with stage I-II endometrioid endometrial cancer whose peritoneal cytology showed malignant or atypical cells (abnormal peritoneal cytology).

Methods: This is a multi-center retrospective study examining 1668 women with stage I-II endometrioid endometrial cancer who underwent primary hysterectomy with available peritoneal cytology results between 2000 and 2015. Abnormal peritoneal cytology was correlated to clinico-pathological characteristics and oncological outcome.

Results: Malignant and atypical cells were seen in 125 (7.5%) and 58 (3.5%) cases, respectively. On multivariate analysis, non-obesity, non-diabetes mellitus, cigarette use, and lympho-vascular space invasion were independently associated with abnormal peritoneal cytology (all, P<0.05). Abnormal peritoneal cytology was independently associated with decreased disease-free survival (hazard ratio 3.07, P<0.001) and cause-specific survival (hazard ratio 3.42, P=0.008) on multivariate analysis. Abnormal peritoneal cytology was significantly associated with increased risks of distant-recurrence (5-year rates: 8.8% versus 3.6%, P=0.001) but not local-recurrence (5.2% versus 3.0%, P=0.32) compared to negative cytology. Among women with stage I disease, abnormal peritoneal cytology was significantly associated with an increased risk of distant-recurrence in the low risk group (5-year rates: 5.5% versus 1.0%, P<0.001) but not in the high-intermediate risk group (13.3% versus 10.8% P=0.60). Among 183 women who had abnormal peritoneal cytology, postoperative chemotherapy significantly reduced the rate of peritoneal recurrence (5-year rates: 1.3% versus 9.2%, P=0.039) whereas postoperative radiotherapy did not (7.1% versus 5.5%, P=0.63).

Conclusion: Our study suggests that abnormal peritoneal cytology may be a prognostic factor for decreased survival in women with stage I-II endometrioid endometrial cancer, particularly for low-risk group.