Endometrial Surveillance in Tamoxifen and Letrozole Treated Breast Cancer Patients

Background: Our study aimed to assess the risk of endometrial pathologies after tamoxifen and aromatase inhibitors (AIs) adjuvant treatment for female breast cancer patients treated at Sultan Qaboos University Hospital in Oman. Materials and Methods: A total of 457 patients diagnosed with estrogen positive breast cancer between January 2011 and December 2018 were screened. Two hundred and four patients met the inclusion criteria, and their detailed clinicopathological and endometrial surveillance data were collected from their electronic health records. Results: All patients underwent endometrial assessment during tamoxifen or letrozole therapy. The mean diagnostic age of breast cancer patients is 43.6 years, ranging from 27-84 years. Eighty-three percent of those patients are premenopausal, and 17% are postmenopausal. The mean tamoxifen use duration was 33 months. The majority of patients, 123 (60.3%), have had tamoxifen for three years or less, 47 (23.1%) for 3-5 years, and only 22 (10.8%) were on tamoxifen for more than five years. Increased endometrial thickness was reported in 8% of the premenopausal and 14% of the postmenopausal group. Other endometrial pathologies that were detected are inactive endometrium three (1.47%), atrophic endometrium three (1.47%), serous carcinoma one (0.50%), endometrial cancer two (0.98%), and chronic endometritis one (0.50%), which were not significantly associated with tamoxifen or letrozole therapy duration. Two patients have developed endometrial cancer, and both are postmenopausal and > 60 years old. Conclusions: Tamoxifen and letrozole did not increase the risk of endometrial cancer in premenopausal patients. Breast Cancer (BC) patients on tamoxifen or letrozole might need a pre-treatment endometrial evaluation and explanation of alarming symptoms to guide further endometrial surveillance.