Breast Cancer Risk Calculator

Breast cancer risk assessment estimates the chance that a person without a breast cancer diagnosis will develop the disease over a defined period. Five-year risk and remaining lifetime risk answer different questions. Neither predicts an individual's future with certainty. Risk models compare information from one person with outcomes observed in large populations, and their accuracy depends on whether the model fits that person's age, ancestry, medical history, and available data. Age is one of the strongest population-level factors. Reproductive history can also influence cumulative hormonal exposure, including age at the first menstrual period and age at a first live birth. A history of breast biopsy may matter because the reason for biopsy and the tissue findings contain information. Atypical hyperplasia is more informative than the biopsy count alone. Breast cancer in a mother, sister, or daughter can raise risk, but the relatives' ages at diagnosis, cancers on each side of the family, ovarian or pancreatic cancer, male breast cancer, and inherited variants may require genetic evaluation. Validated tools have strict definitions. The Breast Cancer Risk Assessment Tool, often called the Gail model, and the Tyrer-Cuzick model do not use identical inputs or populations. Some models include breast density, extended family pedigree, hormone therapy, body measurements, or genetic variants. A result from one model should not be substituted for another or compared without understanding its endpoint and assumptions. This page uses a transparent educational weighting to demonstrate how selected factors can move an estimate. It is not an implementation of a validated clinical model. It does not include race or ethnicity calibration, competing mortality, breast density, detailed pathology, genetic variants, ovarian cancer history, chest radiation, or risk-reducing medication. For that reason, the displayed percentages must not determine mammography timing, MRI screening, medication, genetic testing, or preventive surgery. A healthcare professional can choose an appropriate validated model and verify each input. People with a strong family history, known pathogenic variant, prior chest radiation, atypical biopsy, or concerning breast change may need assessment regardless of an online percentage. Report a new lump, skin or nipple change, or discharge promptly. Screening recommendations vary by country and personal history, so use shared decision-making with a qualified clinician.