Although the prognosis of patients with NSCLC Pancoast tumor has traditionally been poor, recent technological advancements have led to significant improvements in the prognosis of these patients. According to a recent clinical trial, the 5-year survival rate of patients treated with tri-modal therapy was about 50%. 4 There are also published data on patients with Pancoast tumors treated with highdose radiotherapy. The results demonstrate that selected patients with Pancoast tumors treated with high-dose intensity-modulated radiotherapy (IMRT) concurrent with chemotherapy may have longterm disease-free survival. 5,6 Still, most of these patients have low overall survival and very often the late toxicities of treatment cannot be assessed. One of the late side effects of radiotherapy is secondary cancer, which may occur in 17%-19% of patients. The use of radiotherapy increases a patient's risk of developing secondary cancer during their lifetime. 7 Preston et al., 8 have shown that the lungs are more susceptible to develop radiation-induced cancers compared with other organs. Thus, the risk of secondary cancer in patients with lung cancer is highly correlated with radiotherapy and deserves further investigation. 7 As young patients are likely to survive for a longer duration after radiotherapy, they are at a greater risk of developing secondary cancers. 9 Moreover, secondary radiotherapy-related cancer is often a concern in patients treated with radiotherapy for cancers with a better prognosis, such as Hodgkin lymphoma, breast, testicular, cervical, and thyroid cancer. 10 In this paper, we discuss a possible case of secondary cancer in a patient with a stage 4 NSCLC Pancoast tumor that was treated with radical dose lung radiotherapy.