Approximately 6% of patients with stage I to III lung cancer develop second primary lung cancer within 5 years of their initial diagnosis, according to research presented at the International Association for the Study of Lung Cancer (IASLC) 2022 World Conference on Lung Cancer.1
Analysis of data from the National Lung Screening Trial (NLST) showed a rate of second primary lung cancer of approximately 1% to 2% per patient year over a follow-up period of approximately 3 to 5 years. The median time to diagnosis of metachronous primary lung cancers was 2.7 years.
“More than one-quarter (27%) of second primary cancers were diagnosed over 4 years after the date of first primary lung cancer diagnosis, which illustrates the importance of lifelong follow-up,” said study author Alexandra L. Potter, a researcher at Massachusetts General Hospital and President of the American Lung Cancer Screening Initiative.
Alexandra L. Potter
As Ms. Potter explained, with the onset of lung cancer screening in the United States, the number of patients diagnosed with early-stage lung cancer is increasing. Many patients whose screen-detected lung cancers achieve excellent long-term survival, said Ms. Potter, raising the importance of examining the risk of developing second primary lung cancer in this population.
According to Ms. Potter, the risk of second primary lung cancer among lung cancer survivors has been shown to be four- to sixfold greater compared with the risk of lung cancer in the general population after adjusting for age, sex, race, and calendar year.
For this study, Ms. Potter and colleagues examined the incidence, timing, and survival of second primary lung cancers using data from the NLST, a large-scale randomized trial that compared the effectiveness of low-dose computed tomography (CT) vs chest x-ray in reducing lung cancer mortality.
The NLST enrolled 53,454 high-risk individuals aged 55 to 74 years who currently smoked or had quit smoking within the past 15 years. For the present study, the researchers included patients diagnosed with clinical stage I to III initial primary lung cancer. Second primary cancers were categorized as either synchronous or metachronous. Synchronous primary lung cancers were defined as second primary lung cancers that were diagnosed within 6 months of the first primary lung cancer, whereas metachronous primary lung cancers were defined as second primary lung cancers that were diagnosed more than 6 months after the diagnosis of the first primary lung cancer.
Of the 1,971 patients diagnosed with lung cancer in the NLST, 1,405 patients were diagnosed with clinical stage I to III initial primary lung cancer. The incidence of second primary lung cancer was 5.8%, of which 55% were synchronous and 45% were metachronous.
The median follow-up time of patients diagnosed with synchronous primaries was 29.8 months, and the median follow-up time of those diagnosed with metachronous primaries was 65.9 months. Most patients who developed synchronous or metachronous lung cancer in the study cohort underwent surgery for their initial primary lung cancer.
“Among patients with stage I disease, the incidence of metachronous primary lung cancer increased with increasing time from the date of first primary lung cancer diagnosis,” said Ms. Potter.
Similar trends were observed among patients diagnosed with stage II to III second primary lung cancer. However, no second primaries were diagnosed more than 5 years after the date of first primary lung cancer diagnosis among patients with stage II and III first primary lung cancers, said Ms. Potter.
For patients diagnosed with synchronous and metachronous primary lung cancers, the 5-year overall survival from the date of initial primary lung cancer diagnosis was 55.2% and 90.0%, respectively. The 10-year overall survival rates from the date of initial primary lung cancer diagnosis were 39.5% and 30.8% for synchronous and primary lung cancers, respectively.
Overall survival from the date of the second primary lung cancer diagnosis was similar for patients diagnosed with synchronous and metachronous second primary lung cancers. For patients diagnosed with metachronous second primary lung cancers, the 5-year overall survival was 51.8%, and the 10-year overall survival was 22.2%.
DISCLOSURE: Ms. Potter reported no conflicts of interest.
1. Potter AL, Pan M, Mathey-Andrews C, et al: Incidence, timing, and survival of second primary lung cancer in patients in the National Lung Screening Trial. 2022 World Conference on Lung Cancer. Abstract OA05.03. Presented August 7, 2022.