Concurrent chemoradiotherapy versus radiotherapy alone after induction chemoimmunotherapy for stage III NSCLC patients who did not undergo surgery: a single institution retrospective study

Background With remarkable success and few side effects, induction chemoimmunotherapy has been used to improve the prognosis of patients with resectable or potentially resectable non-small cell lung cancer (NSCLC), even in stage III disease. However, for patients who are medically inoperable, unresectable or refuse surgery after induction chemoimmunotherapy, it is unclear whether patients should be treated with concurrent chemoradiotherapy (cCRT) or radiotherapy (RT) alone considering patient safety and tolerability. This study aimed to determine whether cCRT is safe and superior to RT alone after chemoimmunotherapy for stage III NSCLC. Methods Patients diagnosed with stage III NSCLC who received chemoimmunotherapy followed by cCRT/RT alone without surgery at Tianjin Cancer Hospital between November 2018 to December 2021 were retrospectively collected. Patients were divided into two groups: induction chemoimmunotherapy followed by cCRT (cCRT cohort) or RT alone (RT alone cohort). Kaplan-Meier method was used to estimate survival. Univariate and multivariate Cox regression models were adopted to estimate risk factors for PFS. Results Sixty-five patients were included, with 44 (67.7%) received RT alone and 21 (32.3%) received cCRT. Patients in the cCRT group had significantly prolonged PFS (HR = 0.155, p = 0.004), LPFS (HR = 0.225, p = 0.029) and DMFS (HR = 0.028, p = 0.006) than those in the RT alone group. Albeit nonsignificant, a trend toward improved OS (HR = 0.030, p = 0.069) was also observed in the cCRT group. The multivariate analysis further confirmed that cCRT (HR = 0.141, p = 0.008) was the independent factor for promoting a favorable PFS. Treatment-related adverse events were similar between groups (p > 0.05). Patients with consolidation immunotherapy exhibited a trend of improved PFS (HR = 0.398, p = 0.274) and numerically better OS (HR = 0.018, p = 0.209) compared with those without. Conclusions For patients with unresectable stage III NSCLC, cCRT following chemoimmunotherapy appears to be safe and may prolong survival compared with radiotherapy alone. Further investigations on the combination of chemoimmunotherapy and CRT are warranted.