Estradiol Levels and Chemotherapy in Breast Cancer Patients: A Prospective Clinical Study.

Background: Breast cancer remains a global health issue, including in Indonesia, which has a relatively high incidence of breast cancer. Several theories have proved the role of estrogen in breast cancer carcinogenesis, but there is yet to be a preventive measure against breast cancer. Chemotherapy is one of the therapeutic modalities for breast cancer that disturbs ovarian function in producing estrogen due to damaged ovarian granulosa cells. Chemotherapy becomes an alternative option to decreasing circulating estradiol levels through interventions in ovarian functions, either by surgery, such as oophorectomy, or medications that disturb the ovarian functions. This study aimed to observe the estradiol levels in breast cancer patients before and after chemotherapy.

Methods: This was a prospective cohort study. We observed the estradiol levels before and after adjuvant chemotherapy in breast cancer patients. Subjects' characteristics are presented in mean ± standard deviation, distribution frequency, and percentage. Subjects' characteristics based on chemotherapy were tested using an independent -test, Mann-Whitney U, and Chi-square/Fisher exact test. Effects of chemotherapy on estrogen levels were tested using the Wilcoxon rank test and Kruskal-Wallis test.

Results: A total of 194 research subjects were included. There were changes in estradiol levels before and after therapy. The decrease of estradiol levels in patients who did not receive chemotherapy was -6.9% (P > 0.05). Patients who received anthracycline cyclophosphamide (AC) regimen, paclitaxel and anthracycline (TA) regimen, paclitaxel, anthracycline and trastuzumab (TA + H) regimen, and platinum regimen experienced a significant decrease in estradiol levels (-21.4% (P < 0.05), -20.2% (P < 0.001), -31.7% (P < 0.01), and -23.7% (P < 0.05), respectively). Among chemotherapy groups, the estradiol levels before and after chemotherapy did not have significant differences (P = 0.937 and P = 0.730, respectively).

Conclusion: There are no significant differences in estradiol levels between chemotherapy and hormonal therapy groups. Patients in both groups have decreased estradiol levels after therapy, although patients in hormonal therapy do not experience as much decrease as those in chemotherapy.