Adherence to endocrine therapy with tamoxifen and satisfaction with follow-up of women with breast cancer by a gynecologist: A survey study

Background. Side effects of endocrine therapy with tamoxifen (TAM) reduce the quality of life of patients with breast cancer (BC) and adversely affect treatment compliance. Against the background of treatment of BC with TAM, the risk of developing endometrial hyperplasia (EH) increases. At the moment, algorithms for monitoring patients receiving TAM by an obstetrician-gynecologist have not been developed and approved. There are also divergent opinions of experts regarding the diagnosis and management of patients in the detection of EH. This article presents the results of the final stage of the study in 2017–2022 – a survey study. The purpose of this study was to assess adherence to endocrine therapy and satisfaction with observation by a gynecologist of women with BC after 5 years of observation and their relationship with the identified early associated polymorphisms of the CYP2D6, CYP3A5, CYP2C9 and ABCB1 genes. Materials and methods. 54 patients with BC, out of 120 who had previously passed the first pharmacogenetic stage of the study, were interviewed with specially designed questionnaire. Due to the small sample size, delta percentages (∆%) were used in each comparison group with a difference threshold of 5%. To assess associations with the studied genetic polymorphisms, previously obtained significant associations of adverse drug reactions with pharmacogenetics in the same patients were used. Results. The prevalence of all adverse drug reactions (ADRs), with the exception of EH, was higher in the group of patients who canceled TAM. Over 5 years of follow-up, 57.4% of patients were regularly observed by an obstetrician-gynecologist, 42.59% of patients visited a gynecologist less than once a year. Of all the respondents, 53.7% of patients are satisfied with the regularity and quality of dispensary observation by an oncologist, 33.33% of patients are satisfied with the regularity and quality of dispensary observation by an obstetrician-gynecologist. All studied ADRs (EH, hot flashes, asthenia, bone pain and dyspepsia) associated with various genetic polymorphisms, prevailed in the group of patients who stopped taking TAM due to drug intolerance (∆%: 25.72, 6.97, 4.81, 6.97 and 24.52 respectively) compared with the TAM-group. Conclusion. The results obtained confirm the role of the studied genetic polymorphisms in the development of ADRs of TAM, but only systemic (hot flashes, asthenia, bone pain and dyspepsia). With regard to endometrial hyperplasia, no significant differences were obtained, which requires more extensive studies.