Study on Breast Cancer in Kazakhstan Using the Functional Time Series

AIM: In Kazakhstan and Central Asia, breast cancer (BC) is the most common malignancy among women. However, no large-scale study on breast cancer using the functional time series approach has been carried out in Kazakhstan. METHODS: A functional assessment of the age-period-cohort model (APC) and the survival rate (period 2017–2021) was used in the retrospective study. Clinical and demographic information on patients was analysed, including age, gender, region of residence, kind and stage of tumour, occupation, socioeconomic standing, nationality, and specifics of treatment and its outcomes. Additionally, the relationship between nationality, stage, and residency region and the survival rate of breast cancer patients was investigated too. RESULTS: The data of n=22,736 breast cancer patients were analysed. The highest number of breast cancer cases reported was 4,945 (21.7%), in 2019. In 2021, n =4,939 (21.7%) cases were detected, while in 2020, n=4,222 (18.6%) cases were observed. The patients with breast cancer in stages I and Ia were recognized in 6,585 (29% of cases), while those in stages Ib and Ic were confirmed in 8687 (38.2% of cases). In n=10,147 (44.6%) cases, a malignant tumour of the upper outer quadrant of the breast (C50.4) was predominant. Kazakhs made up the majority (n=10,939, 48.1%) of patients with a primary validated diagnosis of breast cancer, followed by Russians (n=7527, 33.1%). Germans had the lowest survival rate overall (11.4 ± 1.7 months) (p ≤ 0.05) (95% CI: 8.0-14.7 months). Uzbeks showed relatively high survival rates of 18.3 ± 1.6 months (95% CI: 15.1-21.5 months) (p ≤ 0.05). The Aktobe region had the lowest breast cancer survival rates, measuring 12.1±0.9 months (95% CI: 10.3-13.9 months) (p ≤ 0.05). The highest survival rates, 18.0±1.3 months (95% CI: 15.5-20.5 months) and 17.9±1.4 months (95% CI: 15.3-20.7 months), were seen in Shymkent and Zhambyl regions (p ≤ 0.05), respectively. The prevalence of breast cancer increases after 37.5 years, according to the results of the APC analysis, with an indicator of 0.572 (95% CI: -0.41 - 1.56), maintaining a steady upward trend in the age range from 42.5 years to 62.5 years. CONCLUSIONS: Despite a slight drop in the disease’s frequency, the incidence of breast cancer in women 37.5 years and older has been stable over the past five years. Additionally, it was shown that the country’s northern regions had a higher incidence of breast cancer cases than the southern and western regions. Our results show the significance of demographic characteristics such as age and location for the development of preventive measures and effective treatment.