CRUCIAL: Analysis of the incidence of second primary cancers in the Spanish thoracic tumor registry according to treatment

BackgroundPatients who have been cured of a first primary lung cancer (FPC) are at increased risk of developing a second primary cancer (SPC). It is currently unknown whether immunotherapy with immune checkpoint inhibitors (ICIs) impacts the risk of developing an SPC. Primary objective: To analyze the risk of second malignancies according to treatment received over time.MethodsPatients were collected through the Thoracic Tumor Registry (TTR) of Spain, an ongoing multicenter prospective registry, where patients are included and followed with an observational nature and nationwide coverage (81 centers over Spain participate). Start of recruitment: August 2016. Time of data extraction: March 2023, with 26,149 patients enrolled. Comparison of treatment groups: χ2 test for categorical variables and ANOVA for quantitative variables. Second malignancy-free survival (Events = presence of a second malignancy or death): Kaplan-Meier method. Comparison survival curves: log-rank test with Benjamini & Hochberg correction method. Median follow-up times: reverse Kaplan-Meier method.Results485 p developed SCP and the median follow-up time for the patients included was 40.6 months. The incidence of SPC is higher in chemotherapy group (2.9%) compared to immunotherapy group (2.1%) and targeted therapy group (1.5%) (p <0.001). Median treatment time is shorter in chemotherapy group (71 days) than in immunotherapy group (179 days) and targeted therapy group (236 days) (p<0.001). The hazard ratio (HR) to develop SCP of immunotherapy and targeted therapy with respect to chemotherapy is HR=0.715 (95%CI 0.688-0.744) and HR=0.688 (95%CI 0.651-0.726), respectively.ConclusionsPatients treated with immunotherapy for lung cancer have a lower hazard ratio to develop SPC than patients treated with chemotherapy. Patients in the chemotherapy group develop more SPC even though they have a shorter treatment exposure time and a shorter or similar follow-up time than targeted therapy or immunotherapy, respectively.Legal entity responsible for the studyFundacion GECP, Spanish Lung Cancer Group.FundingHas not received any funding.DisclosureAll authors have declared no conflicts of interest.