Breast cancer epidemiology in lithuania: assessment of incidence, mortality and survival

Breast cancer is the most common cancer among females in Lithuania and in the other developed countries. Given the fact that this cancer is one of the most pressing health problem for females, it is appropriate to review the epidemiological situation in Lithuania during the period 1978-2007. Cancer registry data was used to analyse incidence, mortality and survival rates. Incidence and mortality trends were evaluated using log-linear regresion model. The the five-year survival rates were calculated by Kaplan-Meier method, the log-rank test was used for comparison of survival differences. From 1978 to 2007 female breast cancer incidence increased annually by 3.03%. By age the incidence rate increased in 50-64 age group (year on year to 2,68%) and in 65-74 age group (1,63% each year after), while the downward trend was observed in females in age groups 35-49 years and 75 years and older (accordingly each year to 1,78% and 3,43%). Early-stage breast cancer incidence rates were increasing: incidence of stage I breast cancer from 1992 year was increasing by 13,13%, stage II by 3,19 % annually. Incidence of stage I and II breast cancer has increased in all age groups. The late stages breast cancer incidence decreased: stage III breast cancer incidence started to decrease since 1997 by 3,85% and stage IV since the 1994-th year by 1,26%. Downward trend was observed in age groups 50-64 years (stage III and IV) and 65-74 years (stage IV). Mortality from breast cancer in 1978-2005 year period was increasig by 2,19%. Positive change in mortality rates observed among patients aged 35-49 years (mortality decreased from 1996 year by 4,55%). In the remaining age groups (50-64, 65-74 and 75 +) mortality rates tended to increase (by 1,03%, 2,17% and 3,17%) respectively. 5-year observed survival rate or breast cancer patients diagnosed with cancer in 1994-2004 years was 58.7%, the average survival was 8,3 years. In the first period (1994-1999 year) five-year survival rate for stage I patients was 86,8%, in the second period (2000-2004) - 88,6%, for stage II rates were 73,3% and 73,5%, for stage III - 42,3% and 42,7%, respectively. The lowest five-year survival rate was found for stage IV (13% and 13,2%). Survival of breast cancer patients at stages I and II was higher in the second period. Five-year survival in the first period in age rours 30-39, 40-49, 50-59, 60-69 and 70+ years were 67,7%, 66,9%, 57,5%, 55,9%, and 40,5%. In the second period survival rate was better - 73,3%, 74,7%, 65,8%, 64,4% and 42,6% respectively. Survival differences by age age were statisticaly significant (X ² = 56,6, p