BACKGROUND: It is controversial whether breast cancer in young women is more aggressive than in older women. This study was initiated to determine age-associated outcome of women with breast carcinoma. METHODS: Patients with breast carcinoma, who were identified in a statewide tumor registry, were divided into age groups based on 10-year intervals (ages 40 and younger, 41 to 50, 51 to 60, 61 to 70, 71 to 80, and older than 80 years). Age at diagnosis, American Joint Committee on Cancer classification, 5-year disease free (5DFS) and cancer specific (5CSS) survival estimates using Kaplan-Meier analysis were determined. RESULTS: Between 1985 and 1992, 3722 women were diagnosed with invasive breast carcinoma. Approximately 5.6% (210) of the women were 40 years old or younger. The youngest age group had the worst 5CSS of 69.7%, followed by the oldest age group (> 80, 5CSS = 71.45%). The age groups 41 to 50, 51 to 60, 61 to 70, and 71 to 80 years had 5CSS of 80.30%, 78.45%, 82.06%, and 84.27%, respectively. The oldest age group (> 80) had the worst 5DFS (39.88%) followed by the youngest age group (< or = 40, 5DFS = 60.79%). The age groups 41 to 50, 51 to 60, 61 to 70, and 71 to 80 years had 5DFSs of 73.22%, 66.87%, 71.53%, and 63.11%, respectively. Analyzed by stage, young (< or = 40 years) women had a worse 5CSS when compared with the other age groups, except for those with Stage I disease. CONCLUSIONS: Our results indicate that women 40 years of age and younger have a worse 5CSS than their older counterparts. This difference in survival is not solely a reflection of more advanced disease but may reflect differences in tumor biology.