Survival of women with breast cancer in Ottawa, Canada: variation with age, stage, histology, grade and treatment

Abstract

This study examined the 5-year survival of 2192 breast cancer women diagnosed between 1994 and 1997 in Ottawa, Canada, by age, TNM stage, histology, grade and treatment, including assessment of the independent value of variables in defining prognosis. Our results showed that age, stage, treatment and grade significantly influenced outcome regardless of the confounding factors considered, with histology failing to achieve significant independent prognostic information. The survival rates were highest at ages 50-69 years for stage I and at ages 40-49 years for stages II-IV. The rates were lowest at ages <or=39 years for stages I-II and at ages >or=70 years for stages III-IV. The differences in survival between grade 1 and grade 3 were 9% in stage I and 20% in stage II. The treatment leading to the best survival was surgery plus radiation for stages I-II and surgery combined with chemotherapy for stages III-IV. Lobular carcinoma had a better prognosis than ductal carcinoma; this can be explained by more grade 1 and less grade 3 cases in lobular carcinoma. The worse prognosis for young patients than other ages can be explained by their higher proportion of poorly differentiated cancers. Stage I patients aged 50-69 years having the best survival is likely due to the earlier diagnosis achieved through screening.