Lymphangioleiomyomatosis as a potent lung cancer risk factor: Insights from a Japanese large cohort study

Background and Objective Lymphangioleiomyomatosis (LAM) is a rare neoplastic disease associated with the functional tumour suppressor genes TSC1 and TSC2 and causes structural destruction in the lungs, which could potentially increase the risk of lung cancer. However, this relationship remains unclear because of the rarity of the disease. Methods We investigated the relative risk of developing lung cancer among patients diagnosed with LAM between 2001 and 2022 at a single high‐volume centre in Japan, using data from the Japanese Cancer Registry as the reference population. Next‐generation sequencing (NGS) was performed in cases where tumour samples were available. Results Among 642 patients diagnosed with LAM (sporadic LAM, n = 557; tuberous sclerosis complex‐LAM, n = 80; unclassified, n = 5), 13 (2.2%) were diagnosed with lung cancer during a median follow‐up period of 5.13 years. All patients were female, 61.5% were never smokers, and the median age at lung cancer diagnosis was 53 years. Eight patients developed lung cancer after LAM diagnosis. The estimated incidence of lung cancer was 301.4 cases per 100,000 person‐years, and the standardized incidence ratio was 13.6 (95% confidence interval, 6.2–21.0; p = 0.0008). Actionable genetic alterations were identified in 38.5% of the patients (EGFR: 3, ALK: 1 and ERBB2: 1). No findings suggested loss of TSC gene function in the two patients analysed by NGS. Conclusion Our study revealed that patients diagnosed with LAM had a significantly increased risk of lung cancer. Further research is warranted to clarify the carcinogenesis of lung cancer in patients with LAM. This study reports the association between lymphangioleiomyomatosis (LAM), a rare disease caused by TSC1 and TSC2 gene dysfunction, and a higher lung cancer risk. It highlights the necessity of vigilant monitoring for lung cancer in LAM patients and calls for more research to understand the mechanisms of carcinogenesis in this disease. See related editorial