Re-thinking the prognostic significance of positive peritoneal cytology in endometrial cancer

Background: Whether abnormal peritoneal cytology (PC) is an independent prognostic factor in endometrial cancer (EC) remains controversial. This study aimed to re-think the prognostic significance of PC in not only all EC patients but also in various subgroups with similar clinicopathological and biological characteristics.

Methods: EC patients who underwent primary surgery of at least a hysterectomy and were pathologically diagnosed with EC in four hospitals affiliated with the Jikei University School of Medicine were retrospectively reviewed. The prognostic significance of PC was evaluated with univariate and multivariate analyses in the entire cohort and subgroups stratified by surgical stages (early/advanced stages), tumor types (types 1/2), and risk classifications (low/intermediate/high).

Results: Of 1963 EC cases, 1616 met the inclusion criteria. Positive PC was identified as an adverse prognostic factor in analyses of all EC cases and in all subgroup analyses stratified by surgical stages and tumor types. In survival curve comparisons, the progression-free survival (PFS) and disease-specific survival in early-stage patients with positive PC were clearly located between those of stage II patients with negative PC and stage III patients. In the subgroup analyses stratified by risk classification in early-stage EC, positive PC was related to poorer PFS in the intermediate- and high-risk groups but not in the low-risk group.

Conclusion: PC status was an independent prognostic factor of EC in all stages and tumor types. Early PC-positive cases, except for the low-risk group, may be recommended for upstaging and should be carefully managed compared with PC-negative cases.