Why does a breast biopsy increase breast cancer risk in the Gail model?
Overall, women who have had a breast biopsy have a slightly increased risk of breast cancer. This is because some biopsy results indicate that a woman has the type of breast tissue that is more prone to develop cancer. Yet the Gail model does not consider the results of an individual woman’s breast biopsy. Instead, the Gail model has determined an average effect of all benign breast biopsy results. Some biopsy results, such as atypical hyperplasia and lobular carcinoma in-situ (LCIS), suggest an increased risk of developing breast cancer, whereas others, such as a cyst or fibroadenoma, do not suggest an increased risk. So, if a woman had a breast lump biopsied, and the lump was diagnosed as a fibroadenoma, Gail may overestimate her risk.
