The aim of this study was to elucidate the diagnostic and prognostic roles of the mean platelet volume (MPV) in various malignant tumors through a systematic review and meta-analysis. The current study included 2,053 patients and 1,396 healthy subjects in 18 eligible studies. We performed a meta-analysis of MPV levels and the mean difference between healthy subjects and pre- and post-treatment patients. Subgroup analysis was conducted based on specific organs and platelet counts. In addition, the correlation between MPV and survival was investigated. The pooled MPVs of healthy subjects, pre-treatment, and post-treatment patients were 8.428 fL (95% confidence interval [CI] 8.118-8.738), 8.831 fL (95% CI 8.582-9.087), and 8.521 fL (95% CI 8.162-8.880), respectively. The mean difference in MPV between healthy subjects and pre-treatment patients was 0.502 (95% CI 0.285-0.719, P < 0.001). However, in lung cancer, the mean difference between pre-treatment patients and healthy subjects was -0.352 (95% CI -0.763-0.060, P = 0.094). The pooled MPV of post-treatment patients was significantly decreased compared to pre-treatment patients. There was no correlation between MPV and disease-free survival rate (hazard ratio 1.033, 95% CI 0.369-2.895). Our results showed that the MPV level was significantly higher in malignant tumors than in healthy subjects and was decreased after treatment. Further cumulative studies will be required before MPV levels can be applied for screening malignant tumors and predicting prognosis.
Keywords: Diagnosis; malignant tumor; mean platelet volume; meta-analysis; prognosis.