Incidence and prognosis in early onset breast cancer.

The aim of this study was to assess the incidence and prognosis in early onset breast cancer. Age-adjusted incidence and death rate for the 5394 Swedish women diagnosed with breast cancer under the age of 40 between 1960 and 1996 was studied using data from the Swedish Cancer Registry and Swedish Death Cause Registry. A total of 107 consecutive young patients with invasive breast cancer undergoing surgery during 1980-1993 in the Southeast Swedish health care region were retrospectively followed up and their cancers reviewed and graded blindly. The median follow-up time was 11.2 years. The applicability of the Nottingham Prognostic Index (NPI) as a prognostic tool was investigated. Grade, age, node status, tumour size, S-phase fraction and steroid receptor content were related to survival univariately and multivariately in a Cox proportional hazard analysis. The incidence of early onset breast cancer has increased moderately and the survival rate has not improved during the last 35 years. When young women are diagnosed with breast cancer their tumours are larger, their lymph nodes more often involved, and the median grade higher than in older with 64% having grade 3 tumours. Lymph node status was the strongest sole prognostic indicator but the use of NPI gave more accurate prognostic information than node status alone.