An analysis of time trends in breast and prostate cancer mortality rates in Lithuania, 1986-2020

Breast cancer (BC) and prostate cancer (PC) mortality rates in Lithuania remain comparatively high despite the ongoing BC and PC screening programmes established in 2006. The aim of this study was to investigate time trends in BC and PC mortality rates in Lithuania evaluating the effects of age, calendar period of death, and birth-cohort over a 35-year time span.

We obtained death certification data for BC in women and PC in men for Lithuania during the period 1986-2020 from the World Health Organisation database. Age-standardised mortality rates were analysed using Joinpoint regression. Age-period-cohort models were used to assess the independent age, period and cohort effects on the observed mortality trends.

Joinpoint regression analysis indicated that BC mortality increased by 1.6% annually until 1996, and decreased by - 1.2% annually thereafter. The age-period-cohort analysis suggests that temporal trends in BC mortality rates could be attributed mainly to cohort effects. The cohort effect curvature showed the risk of BC death increased in women born prior to 1921, remained stable in cohorts born around 1921-1951 then decreased; however, trend reversed in more recent generations. The period effect curvature displayed a continuous decrease in BC mortality since 1991-1995. For PC mortality, after a sharp increase by 3.0%, rates declined from 2007 by - 1.7% annually. The period effect was predominant in PC mortality, the curvature displaying a sharp increase until 2001-2005, then decrease.

Modestly declining recent trends in BC and PC mortality are consistent with the introduction of widespread mammography and PSA testing, respectively, lagging up to 10 years. The study did not show that screening programme introduction played a key role in BC mortality trends in Lithuania. Screening may have contributed to favourable recent changes in PC mortality rates in Lithuania, however the effect was moderate and limited to age groups < 65 years. Further improvements in early detection methods followed by timely appropriate treatment are essential for decreasing mortality from BC and PC.