Kumar, Ashok V.

AbstractBackgroundRecent therapeutic advances and screening technologies have improved survival among patients with lung cancer, who are now at high risk of developing second primary lung cancer (SPLC). Recently, an SPLC risk‐prediction model (called SPLC‐RAT) was developed and validated using data from population‐based epidemiological cohorts and clinical trials, but real‐world validation has been lacking. The predictive performance of SPLC‐RAT was evaluated in a hospital‐based cohort of lung cancer survivors.MethodsThe authors analyzed data from 8448 ever‐smoking patients diagnosed with initial primary lung cancer (IPLC) in 1997–2006 at Mayo Clinic, with each patient followed for SPLC through 2018. The predictive performance of SPLC‐RAT and further explored the potential of improving SPLC detection through risk model‐based surveillance using SPLC‐RAT versus existing clinical surveillance guidelines.ResultsOf 8448 IPLC patients, 483 (5.7%) developed SPLC over 26,470 person‐years. The application of SPLC‐RAT showed high discrimination area under the receiver operating characteristics curve: 0.81). When the cohort was stratified by a 10‐year risk threshold of ≥5.6% (i.e., 80th percentile from the SPLC‐RAT development cohort), the observed SPLC incidence was significantly elevated in the high‐risk versus low‐risk subgroup (13.1% vs. 1.1%, p < 1 × 10–6). The risk‐based surveillance through SPLC‐RAT (≥5.6% threshold) outperformed the National Comprehensive Cancer Network guidelines with higher sensitivity (86.4% vs. 79.4%) and specificity (38.9% vs. 30.4%) and required 20% fewer computed tomography follow‐ups needed to detect one SPLC (162 vs. 202).ConclusionIn a large, hospital‐based cohort, the authors validated the predictive performance of SPLC‐RAT in identifying high‐risk survivors of SPLC and showed its potential to improve SPLC detection through risk‐based surveillance.Plain Language Summary Lung cancer survivors have a high risk of developing second primary lung cancer (SPLC). However, no evidence‐based guidelines for SPLC surveillance are available for lung cancer survivors. Recently, an SPLC risk‐prediction model was developed and validated using data from population‐based epidemiological cohorts and clinical trials, but real‐world validation has been lacking. Using a large, real‐world cohort of lung cancer survivors, we showed the high predictive accuracy and risk‐stratification ability of the SPLC risk‐prediction model. Furthermore, we demonstrated the potential to enhance efficiency in detecting SPLC using risk model‐based surveillance strategies compared to the existing consensus‐based clinical guidelines, including the National Comprehensive Cancer Network.

Abstract Introduction: Radiotherapy has long been examined in association with second malignancies, but the impact of radiotherapy for initial primary lung cancer (IPLC) on the risk of second primary lung cancer (SPLC) remains controversial. We evaluated associations between IPLC radiotherapy and the risks of SPLC and overall mortality among lung cancer survivors. Methods: We identified 689,785 patients diagnosed with IPLC in 1988-2013 from SEER. We applied cause-specific Cox (CSC) regression to evaluate association between IPLC radiotherapy and SPLC risk, adjusting for age at IPLC diagnosis, IPLC stage and histology, and prior history of cancer. To allow a latency period of exposure to IPLC radiotherapy on SPLC risk, we performed subgroup analyses restricted to patients who survived ≥5 and ≥10 years after IPLC diagnosis. Using Cox regression, we evaluated association between IPLC radiotherapy and overall mortality, adjusting for the same covariates used in the CSC analysis. Mediation analysis quantified the indirect effect of IPLC radiotherapy on overall mortality mediated through radiotherapy-driven SPLC diagnosis. Validation utilized data from 7,758 IPLC patients (496 SPLCs) at Mayo Clinic. Results: Of 689,785 IPLC patients, 18,818 (2.7%) developed SPLC in SEER. IPLC patients treated with radiotherapy had a reduced SPLC risk versus non-irradiated patients when evaluated at the time of initial diagnosis (cause-specific hazard ratio [csHR]=0.90, P&lt;1x10-6). However, the association between IPLC radiotherapy and SPLC risk was reversed when analyses were restricted to those who survived at least 5 years (csHR=1.08, P=0.01) and 10 years (csHR=1.16, P=0.009), thus long-term survivors treated with IPLC radiotherapy having a significantly increased risk of SPLC. Mayo Clinic data showed consistent results, with the effect of IPLC radiotherapy increasing from csHR of 2.41 (P&lt;1x10-6) to 3.38 (P=0.001) among 5-year and 10-year survivors, respectively. Similarly, compared to non-irradiated patients, those treated with IPLC radiotherapy showed a significantly increased risk of overall mortality among 10-year survivors (hazard ratio [HR]=1.46, P&lt;1x10-6 in SEER and HR=1.54, P=5.1X10-5 in Mayo Clinic). Mediation analysis showed that a substantial proportion of the total effect of IPLC radiotherapy on overall mortality—ranging from 32% to 59%—was due to radiotherapy-driven SPLC among 10-year survivors in SEER and Mayo Clinic. Conclusions: IPLC radiotherapy is associated with increased risks of SPLC and overall mortality, with its effects more pronounced among long-term survivors. Citation Format: Eunji Choi, Vicky T. Lam, Jacqueline A. Aredo, Ashok V. Kumar, Jason Wampfler, Julie T. Wu, David C. Christiani, Iona Cheng, Christopher I. Amos, Rayjean J. Hung, Leah M. Backhus, Joel W. Neal, Heather A. Wakelee, Ping Yang, Summer S. Han. Long term effect of radiotherapy on risk of second primary lung cancer and overall mortality among lung cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3445.