Using data from the National Lung Screening Trial (NLST), researchers found that the incidence of second primary lung cancer was approximately 4% among the entire cohort of patients with lung cancer and was as high as 8% among patients undergoing surgery for stage IA disease. The research was presented by Potter et al at the International Association for the Study of Lung Cancer (IASLC) World Conference on Lung Cancer 2022 (Abstract OA05.03).
The incidence, timing, and survival of second primary lung cancers are poorly understood, particularly in patients with lung cancers detected via lung cancer screening. Alexandra Potter, a research assistant at Massachusetts General Hospital, and colleagues sought to examine second primary lung cancers using data from the NLST.
Study Details
Patients diagnosed with a first primary lung cancer in the NLST were grouped according to whether they were diagnosed with a second primary lung cancer less than 6 months after first primary diagnosis (synchronous) or longer than 6 months after diagnosis (metachronous). Ms. Potter and colleagues then compared the histology of second primary lung cancers with the first primary lung cancers. The researchers also calculated the incidence rate of metachronous primary lung cancer per 100 person-years, and the 5-year survival rates for patients diagnosed with synchronous and metachronous second primary lung cancers.
Of the 2,053 patients meeting study inclusion criteria, 85 (4.14%) patients developed a second primary lung cancer, of which 48 (56%) were synchronous and 37 (44%) were metachronous. The incidence of second primary lung cancer varied by treatment type and stage and was as high as 8% among patients undergoing surgery for stage IA disease.
For metachronous primary lung cancer, the median time from cancer diagnosis to the diagnosis date was 32.0 months (interquartile range = 17.5–50.5). For patients with early-stage first primary lung cancer, the incidence of metachronous primary lung cancer increased with increasing time from the diagnosis date of the first lung cancer.
Additional Findings
The distribution of second primary lung cancers by histology was 46% adenocarcinoma, 25% squamous cell lung cancer, 8% lepidic adenocarcinoma, and 6% small cell lung cancer. Approximately 44% (n = 37) of patients were diagnosed with second primary lung cancer of the same histologic subtype as their first primary lung cancer. Five-year survival of patients diagnosed with synchronous and metachronous lung cancers from the date of first primary lung cancer diagnosis was 45.6% (95% confidence interval [CI] = 29.9%–60.1%) and 80.3% (95% CI = 63.0%–90.1%), respectively.
“We found that the incidence of second primary lung cancer in the NLST was approximately 1% to 2% per year among the entire cohort of patients with lung cancer. Among patients who underwent surgery for stage IA disease, the incidence rate of second primary lung cancer increased over time after the first primary lung cancer diagnosis,” Ms. Potter reported. “Even 5 years after the date of first primary lung cancer diagnosis, the incidence rate of second primary lung cancer among patients who underwent surgery for stage IA disease was greater than 2% per year.”
