Effects of tamoxifen on cervicovaginal smears from patients with breast cancer

OBJECTIVE: To evaluate the effect of tamoxifen on cervicovaginal epithelium and determine the value of cervicovaginal smears ill identifying patients at risk for endometrial carcinoma. STUDY DESIGN: A group of 48 women with prior breast cancer were divided into three groups: A, taxomifen-treated patients who developed endometrial carcinoma (n=20); B, patients with endometrial cancer not treated with tamoxifen (n =22); and C, tamoxifen-treated patients with no endometrial carcinoma (n = 16). A total of 114 cervicovaginal smears from these patients were evaluated for maturation index, histiocytes, benign and malignant endometrial cells, reactive cellular changes and microorganisms. All patients treated with tamoxifen had received doses of 10 mg twice daily. RESULTS: The maturation index was increased in tamoxifen-treated patients (A and C) versus nontreated patients (B) P less than or equal to.001). The number of cases with endometrial cells was significantly higher in smears of treated patients who developed endometrial cancer (A) as compared to groups B and C (P=.01 and .02, respectively). Histiocytes were also significantly increased in the two groups that subsequently developed endometrial carcinoma (A and B) as compared to the group that did not (group C) (P=.02). There was no significant difference in the presence of reactive cellular changes between the three groups. CONCLUSION: Patients treated with tamoxifen exhibited a partial estrogenic effect in their smears regardless of whether they developed endometrial cancer. However, the presence of endometrial cells in the smears indicated a higher risk of endometrial adenocarcinoma.