Purpose: Breast cancer diagnosed before the age of 50 years has become a common disease in many developed countries. Although average remaining life expectancy in the affected age groups is usually several decades, data regarding survival perspectives beyond 10 to 20 years after diagnosis are sparse. The aim of this study was to assess long-term survival in a large population-based sample of patients diagnosed with breast cancer before age 50 years.
Patients and methods: Relative survival within up to 40 years after diagnosis was assessed for cohorts of women diagnosed with breast cancer before age 50 years and notified to the nationwide Finnish Cancer Registry within various time intervals since 1953. In addition, up-to-date estimates of 40-year relative survival were obtained by exclusively looking at the survival experience of breast cancer patients in recent years (1993 to 1999) using period analysis, a new method of survival analysis.
Results: Prognosis of patients diagnosed with breast cancer before age 50 years has considerably improved during the past decades. According to the latest estimates from period analysis, cumulative 40-year relative survival is now approximately 43% for all cancers combined, 57% for localized cancers, and 24% for cancers with regional tumor spread. Nevertheless, patients diagnosed with breast cancer before age 50 years continue to have increased mortality throughout at least four decades after diagnosis. This applies even if breast cancer is diagnosed in a localized stage and in the absence of a second primary breast cancer.
Conclusion: Despite major improvement in prognosis over time, breast cancer occurring among patients who are younger than 50 years remains a chronic disease that affects prognosis for decades.