Radiotherapy was associated with the lower incidence of metachronous second primary lung cancer

Abstract

Our study aims to estimate the incidence of metachronous second primary lung cancer(SPLC) in initial primary lung cancer(IPLC) survivors and to determine whether radiotherapy affects the risk of metachronous SPLC in the first five years after the diagnosis of lung cancer. Incidence data of IPLC individuals who survived ≥2 years were obtained from SEER-18 database in 2004–2007. Joinpoint regression analysis and competing risk analysis were used to calculate the incidence of metachronous SPLC. Propensity score matching and decision analysis were available to estimate the effect of radiotherapy on metachronous SPLC. 264 of 11657 IPLC survivors with radiotherapy and 1090 of 24499 IPLC survivors without radiotherapy developed metachronous SPLC during 5-year follow-up, respectively. In joinpoint regression analysis, the 5-year incidence of metachronous SPLC in the radiotherapy group was lower than that in the nonradiotherapy group(2385 per 100,000 vs 4748 per 100,000, HR = 0.43,95% CI:0.39–0.47). Competing risk analysis showed that the survivors with radiotherapy were associated with the lower 5 year incidence of metachronous SPLC compared with those without radiotherapy(2.28% vs 4.47%, HR = 0.49,95% CI:0.43–0.57). Through propensity score matching, 4077 pairs of survivors were available to further study that radiotherapy potentially decreased the risk of developing metachronous SPLC with the adjustment of various factors(2.5% vs 3.3%, HR = 0.72, 95% CI:0.55–0.96). Decision analysis suggested that radiotherapy was a negative independent risk factor of metachronous SPLC with clinical net benefit in a range of risk thresholds (2% to 5%). Survivors of IPLC with radiotherapy likely had a low risk of metachronous SPLC during the first five years follow-up, especially non-small cell lung cancer.

Long-term radiation therapy-related risk of second primary malignancies in patients with lung cancer

“…Thakur et al demonstrated a higher risk of developing a second lung cancer in patients with previously treated lung cancer (7). Although many studies also concluded that radiotherapy was significantly associated with an increased incidence of second lung cancer, longterm follow-up results did not support the association in studies by our group and others (9,20,21).…”

“…Similar to our results, one previous study assessed the risk of second thoracic cancer following the diagnosis of the initial lung cancer and found that radiotherapy was significantly associated with an increased risk of second primary esophageal cancer when the latency was set as ≥5 years, but no such significant difference was observed for second primary lung and breast cancers (20). The studies from both Hu et al and Abdel-Rahman et al reported that radiation therapy was significantly associated with a lower incidence of a metachronous second primary lung cancer within 5 years after the diagnosis of the initial lung cancer (20,21). However, in contrast to our study, Berrington de Gonzalez et al concluded that lung cancer patients receiving radiation therapy had an increased risk of developing SPM (9).…”

Triple primary lung cancer: a case report

“…The primary tumor control rate of SRS is 97.6% in medically inoperable early-stage non-SCLC [ 8 ]. Recently, the risk of metachronous MPLC was found to be lower with radiotherapy than non-radiotherapy [ 6 , 8 ] even though in stage IA lung cancer [ 5 ]. The incidence of metachronous MPLC was 0.5% at 1 year and 2.28% at 5 years among solitary PLC survivors with radiotherapy, which was lower compared to the non-radiotherapy group [ 6 ].…”

“…Recently, the risk of metachronous MPLC was found to be lower with radiotherapy than non-radiotherapy [ 6 , 8 ] even though in stage IA lung cancer [ 5 ]. The incidence of metachronous MPLC was 0.5% at 1 year and 2.28% at 5 years among solitary PLC survivors with radiotherapy, which was lower compared to the non-radiotherapy group [ 6 ]. Based on these findings, it is assumed that the SRSs might not induce metachronous MPLC in our patient.…”

“…Smoking and COPD are independent risk factors for MPLC [ 4 ]. PLC increased the risk of MPLC despite stage IA lung cancer [ 5 , 6 ]. We suggest that his history of exposure to exhaust fumes in addition to smoking, COPD, and PLC contributed to the metachronous MPLC.…”