Trends in incidence, molecular diagnostics, and treatment of patients with breast cancer in Kazakhstan, 2014-2019

Abstract

Relevance: Globocan reported 4,390 new breast cancer cases and 1,654 deaths from breast cancer in the Republic of Kazakhstan (RK) in
 2020. Molecular diagnostics of breast cancer includes the determination of Hormone Receptor (HR), HER2, and Ki-67 status to detect patients
 with HR-positive tumors and administer effective treatment.
 Methods: This observational study included a retrospective analysis of incidence, molecular diagnostics, and treatment regimens in
 women with a confirmed breast cancer diagnosis aged 18 years old and older, registered in the RK Electronic Registry of Cancer Patients
 (ERCP) from 1 January 2014 till 31 December 2019.
 Results: In the study period (2014 to 2019), the number of breast cancer cases registered annually has doubled. The incidence increased
 by 46.9%. The share of locally advanced and advanced forms of breast cancer has decreased. The proportion of Luminal type A (HR+/HER2-)
 among newly diagnosed patients ranged from 17.9% to 30%. Chemotherapy and endocrine therapy with goserelin, buserelin, leuprorelin,
 and fulvestrant are standard first- and second-line treatments for HR+ breast cancer. Since fulvestrant indications have been expanded, more
 than 50% of patients with HR-positive advanced breast cancer receive fulvestrant as the first-line therapy.
 Conclusion: Breast cancer incidence growth and a decrease in the share of locally advanced and advanced breast cancer cases in the RK
 could be attributed to increased coverage of eligible women aged 40 to 70 with breast cancer mammographic screening. Although international guidelines support the administration of hormone therapy with or without targeted therapy in women with HR-positive, HER2-metastatic breast cancer, upfront use of chemotherapy remains common in the RK even in the absence of visceral crisis. The use of CDK4/6 inhibitor
 palbociclib in combination with hormone therapy has become routinely available since 2019.