Considerable evidence supports the rationale for postoperative radiotherapy after breast cancer surgery. Moreover, local tumour control affects survival too. High-dose irradiation is inherently associated with an increased risk of secondary malignancies in the long run. This radiobiological phenomenon raises the question whether it is worth taking this hazard, and the exact level of the risk of a secondary malignancy should be clarified. Answering these questions is important, regarding the large population size of breast cancer survivors, as well as patients' improving survival rates and time. The postoperative radiation load to the ipsilateral lung tissue can be reduced, but it is still significant. The current literature review aims to evaluate the risk of secondary lung cancer associated with breast cancer- specific radiotherapy. Published evidence suggests that the benefits of postoperative radiotherapy following breast cancer surgery are much higher than the minimal risk of secondary lung cancer associated with this management strategy.