ONCOLOGY Are endometrial polyps true cancer precursors? Tamar Perri, MD; Kurosh Rahimi, MD; Agnihotram V. Ramanakumar, PhD; Karen Wou, MD; Dragana Pilavdzic, MD; Eduardo L. Franco, PhD; Walter H. Gotlieb, MD, PhD; Alex Ferenczy, MD OBJECTIVE: The purpose of this study was to assess whether endome- trial polyps (EMPs) represent cancer precursors. STUDY DESIGN: Age standardized incidence ratios (SIRs) of histologi- cally verified endometrial cancers (EmCas) were estimated in women with EMPs and in women with uterine leiomyomata, which is a condition that is unrelated to endometrial carcinogenesis. SIRs were calculated as the ratio of observed to expected EmCas based on age-specific inci- dence rates for female Montreal residents during the same period. RESULTS: Of 1467 women with EMPs, 125 (8.5%) had EmCa. Of 1138 patients with uterine leiomyomata, 133 (11.7%) had EmCa. The SIRs of EmCa for women with EMPs (odds ratio, 8.0; 95% confidence interval, 6.6 –9.5) were significantly lower than that in women with leiomyomata (odds ratio, 19.1; 95% confidence interval, 16.0 –22.6). Abnormal uterine bleeding was the main reason for evaluating patients with EMP with or without associated EmCa. CONCLUSION: The findings of higher EmCa incidence are consistent with enhanced detection opportunity rather than with the endometrial cancer precursor potential of EMPs. Key words: cancer precursor, endometrial cancer, endometrial polyp, leiomyomata, uterine bleeding Cite this article as: Perri T, Rahimi K, Ramanakumar AV, et al. Are endometrial polyps true cancer precursors? Am J Obstet Gynecol 2010;203:232.e1-6. E ndometrial polyps (EMPs) are lo- calized exophytic overgrowths of endometrial mucosa. They have not been described in premenarcheal girls. Their incidence peaks in the fifth decade of life and gradually declines after meno- pause. The prevalence of EMPs in the general population has been estimated to range between 7.8% and 25%. 1-3 They are, by far, the most frequent endome- trial disease in menopausal women. EMPs are often associated with bleeding; however, they may also be diagnosed in- cidentally in hysterectomy specimens or by screening or diagnostic endovaginal ultrasonography or hysteroscopy. Traditional teaching has suggested that EMPs are cancer precursors. 4 The risk of EMPs that are associated with en- dometrial carcinoma (EmCa) increases with age, with the highest rate in patients 65 years in whom 32% of the polyps are associated with invasive or noninva- sive malignancy. 5,6 The prevalence of malignant change in EMPs varies from 0.1-13%. 2,3,5-10 Despite these observa- tions, there is no credible evidence that EMP per se is a true cancer precursor or simply represents focal mucosal out- growth with similar biologic characteris- tics and behavior as nonpolyp-contain- ing endometrium. It is also unclear whether the perceived high rate of Em- Cas in patients with EMPs is merely an incidental finding during the diagnostic workup of EMPs, because these patients seek medical attention because of bleed- ing and other symptoms and thus, are subjected to endometrial evaluations. The purpose of our study was to evaluate the prevalence of EmCa in a large num- ber of patients with EMPs and to com- pare these findings with the expected EmCa occurrence in these patients using age-specific incidence rates for the Mon- treal population within the same period. We also aimed to evaluate whether can- cer characteristics are different in pa- tients with polyps, compared with can- cers that are diagnosed in patients without polyps. P ATIENTS AND METHODS Internal review board approval was granted for the study by the Research and Ethics Committee of the Jewish General Hospital, which is an institution affili- ated with McGill University in Montreal, Canada. All patients who were diagnosed consecutively with EMPs between the years of 2000 and 2007 were identified with the computerized database of the Department of Pathology in our institu- tion (n  1880). Clinical and demo- graphic data were extracted from patho- logic requisition forms that included age at diagnosis, reason for referral, menopausal status, use of hormone replacement ther- apy, tamoxifen therapy, presence of other cancers, and means of endometrial evalu- ation for histologic evaluation (eg, biopsy, curettage). All histologic slides were reviewed in- dependently by 2 experienced gyneco- logic pathologists. Discrepant cases were reviewed by a third pathologist who was blinded to the diagnoses of the first 2 pa- thologists. In situations of disagreement, the 3 pathologists reached a consensus From the Division of Gynecologic Oncology, Department of Obstetrics and Gynecology (Drs Perri, Wou, Gotlieb, and Ferenczy), and the Department of Pathology (Drs Rahimi, Pilavdzic, and Ferenczy), Jewish General Hospital; the Division of Cancer Epidemiology, Departments of Oncology and Epidemiology (Drs Ramanakumar and Franco), McGill University, Montreal, Quebec, Canada. Reprints: Alex Ferenczy, MD, Professor of Pathology and Obstetrics & Gynecology, Department of Pathology, Jewish General Hospital, 3755 Cote Sainte-Catherine Rd., Montreal, Quebec, Canada H3T 1E2. alex.ferenczy@mcgill.ca. Authorship and contribution to the article is limited to the 8 authors indicated. There was no outside funding or technical assistance with the production of this article. 0002-9378/$36.00 © 2010 Mosby, Inc. All rights reserved. doi: 10.1016/j.ajog.2010.03.036 Research www. AJOG.org 232.e1 American Journal of Obstetrics & Gynecology SEPTEMBER 2010