Platelet count and mean platelet volume are associated with not only bone, soft tissue, and lymph node metastases but also with malignant pleural effusion in lung cancer patients.

An increased platelet count is often observed in lung cancer patients. Whether and how the platelets affect cancer progression have yet to be established. The aim of the study was to investigate the involvement of the platelet count and mean platelet volume (MPV) in the prognosis and progression of lung cancer patients. This retrospective study included 146 patients with newly diagnosed primary lung cancer. The platelet count and MPV were measured before invasive diagnostic procedures and treatment. These platelet indices, overall survival of the patients, and tumor metastases for each organ were analyzed. On Kaplan-Meier survival analysis, the overall survivals of patients with platelet counts ≤ 244.0 × 109/L or MPV > 9.7 fL were longer than those of patients with platelet counts > 244.0 × 109/L or MPV ≤ 9.7 fL. Cox regression analysis showed that poor performance status, increased platelet count, and increased C-reactive protein were independent prognostic factors. The platelet indices were associated with metastases to bone, soft tissue, and lymph node, in addition to malignant pleural effusion. Increased platelet count and decreased MPV were unfavorable prognostic factors for patients with lung cancer, and they were involved in bone, soft tissue, and lymph node metastases and malignant pleural effusion.