Tumors associated with radiotherapy: a case series

BACKGROUND: Breast cancer is the cancer with the highest incidence and mortality worldwide. Its treatment is multidisciplinary with surgery, systemic therapy, and radiotherapy. In Colombia, according to Globocan 2018, there is an age-standardized incidence rate of 44 per 100,000 women. Radiotherapy improves local and regional control in patients with breast cancer, and it could even improve relapse-free survival and overall survival in patients with nodal disease. The toxicity of this treatment in most cases is mild and transient, but in a low percentage of patients, radiotherapy-induced tumors may develop. CASE PRESENTATION: Seven Colombian patients treated for breast cancer at our institution developed radiotherapy-induced tumors between 2008 and 2018. The median age was 54.4 (range 35–72) years. Six patients had locally advanced tumors at the time breast cancer was diagnosed, and all of them received neoadjuvant or adjuvant chemotherapy and radiotherapy. The radiotherapy-induced tumors were five sarcomas, one of which was a well-differentiated angiosarcomatous vascular lesion with negative c-Myc (benign lesion), and the remaining patient had basal cell carcinoma associated with radiotherapy. CONCLUSIONS: Sarcomas are the most common radiotherapy-induced tumors after breast cancer treatment. These are rare, aggressive tumors and represent between 0.5% and 5.5% of all sarcomas. Basal cell carcinoma has also been associated with breast cancer treatment. The management is individualized and multimodal, including surgical resection and chemotherapy. Different studies have shown that radiation therapy is a risk factor for the development of soft tissue tumors.