A study published in BMC Cancer evaluated the predictive ability of the combined skeletal muscle index (SMI) and prognostic nutritional index (PNI) to evaluate probability of survival after surgery for advanced gastric cancer. In total, 650 patients from 2 centers were included in the analysis.
The study enrolled 290 patients who underwent radical gastrectomy for advanced gastric cancer from the First Affiliated Hospital of Dalian University in Liaoning Province, China, and 260 patients from the Fujian Medical University Union Hospital in Fujian Province, China. Patients presented with clinical tumor stage II or III and had no history of radiotherapy or chemotherapy. Patients received conventional chemotherapy following surgery. Clinical data were collected, along with preoperative abdominal computed tomography images, hematology-related examinations, tumor-related characteristics, and surgical and follow-up data. Postoperative follow-up was conducted every 3 months during the first 2 postoperative years, and then every 6 months thereafter.
SMI was calculated using imaging of the L3 vertebral level muscle area, and PNI was calculated based on serum albumin and lymphocyte count indicators. SMI was used to evaluate the presence of sarcopenia. According to the authors, while PNI is used as a comprehensive predictor of survival in patients with cancer, the tool has “certain limitations because it cannot reflect the biological characteristics of the tumor itself.” Thus, the addition of data from the SMI, which assesses muscle mass, may help to improve the predictive accuracy when combined with PNI.
The primary outcomes were overall survival (OS) and disease-specific survival (DSS). Both SMI and PNI outcomes were significantly correlated with postoperative survival according to the Kaplan-Meier survival analysis. The novel combined index, smni, was calculated for each patient.
Smni was significantly associated with both 3-year OS (P<.001) and DSS (P<.001). Univariate and multivariate analysis demonstrated that smni was an independent prognostic risk factor for 3-year OS and DSS. “In the data from 2 centers, the predictive ability of the combined indicator smni for the postoperative survival of gastric cancer patients as an independent risk factor is similar to and significantly higher than that of other risk factors such as [hematological index] FIB and [carcinoembryonic antigen],” the authors concluded. The predictive ability was also higher than the use of SMI and PNI for fitting, which “suggests that the combined indicator smni has a more excellent and stable predictive ability.”
The authors acknowledged several limitations, such as potential information and selection biases. They also noted that a larger and more diverse sample is needed to confirm these findings, as is the addition of patients who received preoperative neoadjuvant chemotherapy. “Future studies can also explore other aspects of the issue, such as the relationship between the combined indicator smni and other predictors of postoperative survival in gastric cancer patients, such as inflammatory markers, biochemical blood indicators, and other nutritional indicators,” they wrote.
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