Second malignancies in breast cancer patients following radiotherapy: a study in Florence, Italy

In order to evaluate the long-term consequences of radiotherapy, a cohort study was conducted based on clinical records for 5,248 women treated for breast cancer in Florence (Italy), with continuous follow-up from 1965 to 1994. The Cox proportional hazards model for ungrouped survival data was used to estimate the relative risk for second cancer after radiotherapy.This study indicated an increased relative risk of all second cancers combined following radiotherapy (1.22, 95% CI: 0.88 to 1.69). The increased relative risk appeared five or more years after radiotherapy and appeared to be highest amongst women treated after the menopause (1.61, 95% CI: 1.13 to 2.29). Increased relative risks were observed specifically for leukaemia (8.13, 95% CI: 0.96 to 69.1) and other solid cancers (1.84, 95% CI: 1.06 to 3.16), excluding contralateral breast cancer. For contralateral breast cancer, no raised relative risk was observed during the period more than five years after radiotherapy.The study indicated a raised risk of second malignancies associated with radiotherapy for breast cancer, particularly for women treated after the menopause.Breast cancer is the most common type of cancer and the major cause of cancer-related mortality among women worldwide [1]. Many patients are diagnosed with this disease each year and are often treated with surgery followed by adjuvant radiation therapy [2]. The use of radiation therapy has increased dramatically since randomised trials in the 1980s showed equivalent outcomes for patients treated with breast conserving surgery and radiation therapy and those treated with modified radical mastectomy [3-5]. With advances in early diagnosis and treatment, breast cancer is becoming an increasingly survivable disease resulting in a large population of long-term survivors. Recent trials have shown an overall survival benefit in favour of adjuvant radiotherapy for breast cancer [6-8]. Nevertheless, there is clear evidence for the association between r