The potential oncogenic effect of tamoxifen on the endometrium.

We report the case of an in-situ endometrial adenocarcinoma with severe atypical hyperplasia which developed while the patient was on tamoxifen only 1 year after endometrial resection for benign pathology. A 55-year-old woman received tamoxifen as adjuvant therapy for breast cancer treated in 1994. At that time, a benign endometrial polyp was also removed before initiating tamoxifen treatment. In 1997, endometrial resection was performed for benign pathology (atrophic cystic endometrium). In 1998, an endometrial adenocarcinoma was diagnosed. This case illustrates that endometrial resection does not protect women taking tamoxifen against subsequent development of severe atypical lesions

Uterine side effects of tamoxifen: a need for systematic pretreatment screening.

OBJECTIVE: To determine the effect of tamoxifen on the endometrium in postmenopausal women with breast cancer and to try to identify, by pretreatment screening, subjects at higher risk of developing endometrial cancer. METHODS: Between January 1993 and January 1996, 264 postmenopausal women with breast cancer were studied prospectively with pelvic ultrasonography. Outpatient hysteroscopy and endometrial biopsy were done if ultrasound abnormalities were detected. Initial endometrial evaluation was done before treatment with tamoxifen was started, 20 mg daily, and annually thereafter. Attention was focused on endometrial lesions and, especially, endometrial hyperplasia, which was defined according to World Health Organization classification. Endometrial hyperplasia was subdivided into two broad categories: hyperplasia without cytological atypia and hyperplasia with cytological atypia. Adenocarcinoma in situ was defined as a well-differentiated endometrial carcinoma confined to the endometrial mucosa without myometrial invasion. RESULTS: Forty-six women (17.4%) had asymptomatic endometrial lesions diagnosed before starting tamoxifen, and two of these were atypical lesions. Patients with initial lesions and those without initial lesions were followed separately. At 3 years of follow-up, the incidence of atypical lesions was significantly higher in women with lesions initially than in those without (three lesions among nine women versus one lesion among 51 women, P = .009). CONCLUSION: It appears that a group of high-risk subjects can be defined on the basis of endometrial evaluation before tamoxifen therapy; these women should be followed carefully because of the high incidence of severe atypical lesions

L'évaluation endométriale préalable au tamoxifène: résultats préliminaires d'une étude prospective.

The objective of this study was to try to identify, by pretreatment screening, a group of patients at higher risk of developing endometrial carcinoma on tamoxifen. Between January 1993 and January 1997, 360 postmenopausal patients with breast cancer were enrolled in this prospective study. Basal screening included gynaecologic examination with a Papanicolaou smear and endovaginal sonography. In the case of an abnormal ultrasound (endometrial thickness greater than 4 mm), an outpatient hysteroscopy with an endometrial biopsy was carried out. These examinations were repeated annually. By means of this preliminary evaluation, two groups of patients were identified: patients without initial lesions (group I) and patients with initial endometrial lesions (group II). These two groups of patients were followed up separately exactly in the same way. Endometrial lesions taken into account were: adenocarcinomas (in situ and invasive), polyps with or without atypia, myomas and adenomyotic lesions with irregular mucosa. After 3 years and after 4 years of follow-up, the percentage of atypical lesions was significantly higher in the group with initial lesions than in the group without initial lesions. This study suggests that a group of high risk patients more sensitive to the carcinogenic effect of tamoxifen can be identified by pretreatment evaluation