Modulated Radiotherapy for Breast Cancer: Locoregional Outcomes

Introduction: Breast cancer treatment has evolved considerably over past several decades to enable safe treatment with maximal control and minimum toxicity. Understanding of recurrence patterns with respect to disease stage and biology have enabled fine tuning of radiotherapy (RT) volumes as well as doses. We analysed the data of our breast cancer patients who received local or locoregional radiotherapy with newer techniques to determine recurrence and toxicity patterns Methods: Treatment records of patients treated with curative intent radiotherapy between November 2009 and November 2013 at division of Radiation Oncology at our institute were analysed. Demographics, treatment details and outcomes were determined from recorded data. Stata software version 9 was used for analysis. Results: 364 patients with stages I to III was included. Median age was 55 years. Most common histology was invasive ductal carcinoma. 68% patients were hormone receptor positive. 22.4% patients had pathologic high risk characteristics. 14.1% pts received neoadjuvant chemotherapy. 48.3% had modified radical mastectomy (MRM), 50.8% had breast conservation therapy while 0.8% had completion mastectomy following lumpectomy elsewhere. Most common RT technique was intensity modulated radiation therapy (74.1%). 3.3% pts had grade 3/4 skin toxicity and 11% had grade 3/4 myelosuppression requiring treatment interruption. There was no difference in toxicity between treatment techniques. After a median follow up of 30 months, there were 39 recurrences (24 distant metastases, 4 locoregional and 4 at both locoregional and distant sites simultaneously). 5 year disease free survival was 86%. Higher T and N stage on pathology and MRM were significantly associated with inferior disease free survival. Conclusion: Modern RT techniques provide an acceptable locoregional control while minimising toxicities. Omission of axillary radiotherapy in our patients did not increase the risk of locoregional recurrence.