Age-of-onset heterogeneity in hereditary breast cancer: minimal clues for diagnosis.

Knowledge of the family history of cancer may significantly influence diagnosis and surgical management. Hereditary breast cancer (HBC) is common and accounts for approximately 9% of the total breast cancer burden. The pattern of HBC's natural history, including age of onset, increased incidence of bilaterality, integral tumor combinations in certain kindreds, and vertical transmission consonant with an autosomal dominantly inherited factor, when observed in context with the family history, enables pattern recognition so that the diagnosis might be facilitated. We describe seven families from our Hereditary Cancer Consultation Center (HCCC) and the Creighton Oncology Clinic which are noteworthy for extraordinarily early age of onset. This appears to be an additional example of heterogeneity in HBC and may represent the first account of this remarkable subset. The manner in which age of onset can be incorporated with other aspects of natural history for expediting diagnosis is discussed.