The Special Case of Previous Chest Radiation Therapy

Abstract

The risk of developing a secondary cancer after chest radiation therapy (CRT), largely used to treat malignancies, in particular, Hodgkin lymphoma (HL), is higher than that of the general population. Breast cancers (BCs) are the most common female solid tumors in survivors of HL, with 8.23 relative risk and onset at a younger age (40 versus 61 years) in comparison with the general female population, so that in these women the BC risk is similar to that in BRCA mutation carriers. A positive correlation with the radiation dose and an inverse correlation with age at HL diagnosis were observed. The most common pathological BC subtype is invasive ductal, estrogen receptor negative, and triple negative, but a high frequency of ductal carcinoma in situ (DCIS) up to 50% was reported. The most frequent locations are the upper outer quadrants, within or at the margin of the CRT field. At mammography, BCs mostly appear as irregular masses and differently from BRCA mutation carriers microcalcifications have been reported in 25% of the cases. Several medical bodies recommend a surveillance based on annual mammography and MRI, with different thresholds for CRT doses and different time intervals from CRT to the start of surveillance. The Children’s Oncology Group recommends annual mammography plus MRI screening since 8 years after CRT or at 25 years of age, whichever occurs last. The use of mammography as adjunct to MRI is based on the following: MRI sensitivity is lower (63-80%) and that of mammography is higher (67-70%) than those observed in women with hereditary BC predisposition, due to a higher incidence of DCIS with microcalcifications and low neoangiogenesis in lymphoma survivors. A sensitivity close to 95% can be obtained only by combining both tests.