Secondary malignancies in survivors of breast cancer: how to overcome the risk.

Secondary radiation-induced cancers (SRIC) are rare but well-documented as long-term side effects of radiation in a large population of breast cancer survivors. The estimate of the standardized incidence ratio is 1.2, increasing with time elapsed from irradiation, and influenced by age, genetic and environmental backgrounds of the patient and systemic treatments. The majority of SRIC occurs in or close to high-dose treatment volume in the intermediate dose level. It is a dose- and rate-dependent phenomenon that rarely occurs in tissues with a cumulative dose of <3.5Gy. Careful patient selection, thorough treatment planning and modern radiation equipment can reduce the dose to the surrounding tissues and decrease the incidence of SRIC.