Synchronous peritoneal metastases from lung cancer: incidence, associated factors, treatment and survival: a Dutch population-based study.

Peritoneal metastases (PM) from lung cancer are rare and it is unknown how they affect the prognosis of patients with lung cancer. This population-based study aimed to assess the incidence, associated factors, treatment and prognosis of PM from lung cancer. Data from the Netherlands Cancer Registry were used. All patients diagnosed with lung cancer between 2008 and 2018 were included. Logistic regression analysis was performed to identify factors associated with the presence of PM. Cox regression analysis was performed to identify factors associated with the overall survival (OS) of patients with PM. Between 2008 and 2018, 129,651 patients were diagnosed with lung cancer, of whom 2533 (2.0%) patients were diagnosed with PM. The European Standardized Rate of PM increased significantly from 0.6 in 2008 to 1.4 in 2018 (p < 0.001). Age between 50 and 74 years, T3-4 tumour stage, N2-3 nodal stage, tumour morphology of a small cell lung cancer or adenocarcinoma, and the presence of systemic metastases were associated with the presence of PM. The median OS of patients with PM was 2.5 months. Older age, male sex, T3-4 tumour stage, N2-3 nodal stage, not receiving systemic treatment, and the presence of systemic metastases were associated with a worse OS. Synchronous PM were diagnosed in 2.0% of patients with lung cancer and resulted in a very poor survival.