This study reported the incidence of lymphopenia in 271 stage III NSCLC patients treated with IMPT (n=71) vs IMRT (n=200) and concurrent chemotherapy. The incidence of lymphopenia grade ≥ 3 was 67 % and 47 % in the IMRT and IMPT group (P = 0.03). The incidence of anemia grade ≥ 3 was 26 % and 9 % in the IMRT and IMPT group (P = 0.001). IMPT was associated with a lower rate of Performance Status (PS) ≥ 2 at day 21 and 42 after CCRT (13 % vs. 26 %, P = 0.04, and 24 % vs. 39 %, P = 0.02). Concurrent chemo-radiotherapy followed by adjuvant durvalumab is standard-of-care for fit patients with unresectable stage III NSCLC. Patients treated with IMPT had a higher probability of receiving adjuvant durvalumab (74 % vs. 52 %, P = 0.01).