Sarcopenia among treated cancer patients before and after neoadjuvant chemotherapy: a systematic review and meta‐analysis of high-quality studies

Background Neoadjuvant chemotherapy, used to shrink tumors before surgery, is increasingly applied in clinical practice. However, retrospective studies indicate that it may increase sarcopenia rates and consequently result in an elevated occurrence rate of postoperative severe complications such as severe surgical incision infection, severe respiratory failure, and severe postoperative hemorrhage, especially in the elderly population. Currently, no systematic analysis examines the association between neoadjuvant chemotherapy and sarcopenia. This study aims to fill this gap with a comprehensive meta-analysis focused on this critical aspect of the field. Methods A systematic literature search was conducted in the PubMed and Web of Science databases from their inception to January 2024. The included studies encompassed patients who received neoadjuvant chemotherapy and underwent computed tomography (CT) scans both before and after treatment to calculate skeletal muscle index (SMI) or categorize them for the presence of sarcopenia. The determination of sarcopenia status was based on well-established and validated threshold criteria. Data extraction was performed independently by two reviewers. A meta-analysis was employed to estimate the pooled odds ratio (OR) and its corresponding 95% confidence interval (95% CI) to assess the risk of neoadjuvant chemotherapy-induced muscle reduction. Results In the 14 studies with complete categorical variable data, comprising 1853 patients, 773 patients were identified as having sarcopenia before neoadjuvant treatment and 941 patients had sarcopenia after neoadjuvant therapy. The OR and its 95% CI was calculated as 1.51 [1.31, 1.73]. Among these, 719 patients had digestive system cancer, with 357 patients having sarcopenia before neoadjuvant treatment and 447 patients after, resulting in an OR of 1.74 [1.40, 2.17]. In the remaining 1134 patients with non-digestive system cancers, 416 were identified as having sarcopenia before neoadjuvant treatment, and 494 patients had sarcopenia after, with an OR of 1.37 [1.15, 1.63]. Additionally, in seven studies with complete continuous variable data, including 1228 patients, the mean difference in the change of SMI before and after neoadjuvant treatment was − 1.13 [− 1.65, − 0.62]. After excluding low-quality small-sample studies with fewer than 50 patients, the same trend was observed in the analysis. Conclusion The risk of muscle reduction significantly increases in cancer patient