Monson R R, Yen S, MacMahon B
Lancet. 1976 Jul 31;2(7979):224-6. doi: 10.1016/s0140-6736(76)91026-6.
733 women in whom chronic mastitis had been diagnosed were followed for an average of 30-3 years. 49 died from breast cancer compared with an expected number of 18-8. The excess risk of dying from breast cancer persisted for at least 30 years after chronic mastitis was diagnosed.