Malignant Potential of Positive Peritoneal Cytology in Endometrial Cancer

Abstract & commentary

Synopsis: Evidence suggests that endometrial cancer cells found in the peritoneal cavity usually disappear within a short time and seem to have a low malignant potential.

Source: Hirai Y, et al. Obstet Gynecol. 2001;97:
725-728.

Hirai and colleagues report a study of 50 patients with clinical stage I-II endometrial cancer in whom the disease was completely surgically resected and positive peritoneal cytology was found at surgery. The purpose of the study was to investigate the malignant potential of positive peritoneal cytology in endometrial cancer. A tube for cytologic analyses was inserted into the peritoneal cavity when closing the abdomen. The peritoneal cavity was irrigated with physiologic saline, and washings were obtained through the tube 7 and 14 days after the operation. Persistence of positive peritoneal cytology was observed in 4 of 7 patients with adnexal metastasis, 0 of 9 patients with nodal disease, and 1 of 34 patients with disease confined to the uterus, for a total of 10% (5 of 50). In the remaining 45 (90%) patients, no malignant cells were found in any of the washings. Hirai et al concluded that the current series suggests that endometrial cancer cells found in the peritoneal cavity usually disappear within a short time and seem to have a low malignant potential. They also theorized that only malignant cells from special cases, such as adnexal metastasis, may be capable of independent growth, and are possibly associated with intraperitoneal recurrence.

Comment by David M. Gershenson, MD

The influence of positive peritoneal cytology in patients with endometrial cancer has been a topic of great controversy over the past several years. Although several early studies strongly suggested that positive peritoneal cytology had an independent adverse effect on relapse and survival, findings from more recent studies have indicated that peritoneal cytology is not an independent prognostic or risk factor. In other words, other prognostic factors—depth of myometrial invasion, histologic grade, histologic type, and lymph node status—are much more important in determining outcome. If a patient has positive peritoneal cytology but no other unfavorable risk factors, current philosophy dictates that no adjuvant therapy is recommended. The current study gives some credence to this therapeutic strategy. Even though peritoneal cytology may be positive, the cells may not have metastatic potential or be viable for long periods of time. As Hirai et al also point out in their article, these findings also have implications for the debate about dissemination of endometrial cancer cells at the time of hysteroscopy. Current evidence strongly suggests that malignant cells can be disseminated into the peritoneal cavity at the time of hysteroscopy, but this study lends support to the theory that those cells have low malignant potential. I find this study to be simplistic in its design but potentially important in elucidating the true meaning of positive peritoneal cytology in patients with endometrial cancer.