Variations in Serum Levels of Estradiol, Vitamin D and Calcium in Women with Breast Cancer on Tamoxifen

Abstract

Background: Tamoxifen works as a selective estrogen receptor modulator (SERM) by binding to estrogen receptors on mammary epithelium and inhibiting estrogen's proliferative activity on the mammary tissues. however, it has a little estrogen agonistic impact on bone, liver, and endometrial. Aim: This cross-sectional study aimed to investigate the variations in serum estradiol, vitamin D and calcium levels in postmenopausal breast cancer women on tamoxifen. Methods: This study is conducted at the oncology center in Kerbala/Iraq at Imam al-Hussain medical city during the period between November (2021(and May (2022), the patients were divided into groups according to their ages, BMI, duration of disease and duration of treatment. A blood sample from 100 breast cancer patients (being on tamoxifen for at least 3months) were taken and laboratory tests done by measuring plasma levels of (estradiol, vitamin D and calcium) to assess its effect. Ethical approval and interviews with the patients were performed. Results: The mean age of 100 patients was 51 years. As serum calcium and vitamin D increased, serum estradiol level decreased with age and there were statistically significant changes with different age groups (P value<0.001). Besides that, the increasing in BMI accompanied by increasing levels of serum calcium, estradiol and vitamin D with statistically significant change in serum vit. D between the obese and non-obese groups (P value= 0.002). Finally, Serum calcium, estradiol and vitamin D were decreased upon long term of disease and tamoxifen use (>5years). Conclusion: Tamoxifen shows significant positive influence on hormonal level of estradiol and calcium with negative effect on vitamin D in female patients with breast cancer.