Prognostic factors and long-term survival in breast cancer in a defined urban population

During the years 1945-1965 461 women in the city of Turku, Southwestern Finland, were diagnosed as having a biopsy-verified breast cancer. Four-hundred and thirty-nine patients (95%) with complete clinicopathologic data have now been followed up for a mean of 28 years (range from 22 to 42 years) or until death. The survival rate corrected for intercurrent deaths was 44%, 35%, and 34% 10, 20, and 30 years after the diagnosis, respectively. Only 1.2% of all deaths caused by breast cancer occurred more than 20 years after the diagnosis, and therefore about one third of the patients are likely to be cured. Fifty-six (12.8%) patients developed a second primary breast cancer or cancer of other sites. Survival of the patients diagnosed in the 1960s was better than that of the patients diagnosed earlier (p = 0.02), but the relative percentage of prognostically unfavorable poorly differentiated (Gr III) cancers became smaller with time (p = 0.009). Axillary nodal status was the most important independent prognostic factor for the 342 patients with an operable, unilateral, and invasive breast cancer in Cox's multivariate analysis (p less than 0.001), followed by histologic grade, type of tumor margin, the primary tumor size (p less than 0.001), and the extent of tumor necrosis (p = 0.003). Histologic type, mitotic count, nuclear pleomorphism, extent of tubule formation, amount of elastin, and extent of intraductal tumor growth were also significant prognostic factors in a univariate analysis.