This study aims to determine the psoas muscle index as a precise factor for surgical outcomes. Based on the obtained results, PMI is a potent predictor of hospitalization time, independent of gender. Therefore, this index promises to be a reliable indicator of post-surgery complications regardless of other clinical or demographic characteristics. The notability of PMI is that it is easily accessible and does not require dedicated attainment. Almost all patients with GI cancers have been imaged before surgery and therefore do not need additional radiation. The best site in cross-sectional imaging to determine the PMI is in the range of the L3 vertebra, which is recognizable in CT of the abdomen and pelvis of these patients(16). This index needs to adjust based on the patient's height to provide a comparable value of sarcopenia(11, 17). In this study, the relationship of PMI with a higher period of hospitalization as an indicator of poor survival compared to age and BMI has been specified. Overweight cancer people are advantaged more than other patients from the preference of PMI over BMI because weight loss, one of the well-known cancer clues, may not be observable in obese people, and the high weight of these patients conceals such losses. However, sarcopenia can efficiently be recognized in them. As a result, and based on this study, it is recommended to measure muscle quantity from the beginning of the assessment, especially in overweight people.
This radiological index is also related to the physical potency of patients before performing tumor resection surgery; and is a more accurate factor than BMI and age in the quantity of the hand grip strength test. HGS is directly related to the mortality of cancer patients and is used to identify the nutritional situation of patients who are candidates for gastrointestinal surgery(18). This low-price and accessible test refers to the maximum strength of each hand in kilograms. Our investigation revealed that PMI correlates to HGS of both hands and increases the validity of preoperative exercise testing.
The prevalence of sarcopenia in all types of GI cancers is clarified, which indicates that it is caused by a similar mechanism of malignancies, regardless of its kind(19–21). There are various factors involved in creating alterations in muscle fibers leading to sarcopenia, such as increased apoptotic activity due to the down-regulation of certain hormones like growth hormone and insulin, proteolysis of muscle tissue by increasing the levels of pro-inflammatory mediators like tumor necrosis factor-alpha and interleukin 6, and Mitochondria instability due to the increase of oxygen-containing reactive species (ROS). Decreased intake of adequate nutrients due to inflammatory substances causing diminished appetite also leads to muscle changes visible on imaging(22, 23). Accordingly, the decrease in muscle volume could be a practical guide toward understanding the transformation at the cellular and molecular level of these patients. In addition to the microscopic interactions due to malignancies, various types of cancer treatment can also accelerate the occurrence of sarcopenia. Antineoplastic drugs are of particular importance. Several anti-cancer drugs worsen sarcopenia and exacerbate its adverse effects, which cause toxicity induced by chemotherapy and reduce the response to treatment. Therefore, the association between chemotherapy and sarcopenia is two-way, and each aggravates the unfavorable effect of the other(24, 25). Radiotherapy is another treatment option for GI cancers, including pancreatic and rectal cancer. The impact of sarcopenia on survival after radiotherapy of head and neck cancer patients is well known(26–28). The prognostic value of PMI in radiotherapy of GI cancers requires further research. Also, an additional investigation needs to determine radiotherapy-induced changes in the process of sarcopenia.
After estimating the PMI and distinguishing the high-risk people, treatment approaches for improving the patient's life expectancy recommend. Different processes have been investigated to reclaim muscle mass in individuals with cancer. Proper nutrition is one of the considerable ways to gain adequate muscle capacity(29). For instance, anti-inflammatory materials such as Eicosapentaenoic acid (EPA) found in fish or separately; are beneficial to gain weight and appetite in patients at risk of body composition changes without remarkable side effects. Vitamin D supplements with whey protein and adequate exercise also recommend for low muscle mass treatment(30). In addition, contractile protein mass can enhance by resistance training. These exercises diminish sarcopenia by reducing body fat, increasing muscle strength, and building muscle through protein(31, 32). It is recommended that validated therapeutic modalities be considered for individuals with sarcopenia who are scheduled to undergo tumor resection surgery. Such interventions should be performed under the recommendation of a qualified nutritionist and exercise specialist to decrease the risk of post-surgical morbidity.
Previous research has explored the influence of sarcopenia on the prognosis of patients with GI malignancies and its impact on chemotherapy response and physical strength. The present study seeks to clarify the importance of the defined PMI as an indicator of sarcopenia regarding postoperative complications in this population. Under its accessibility before surgery, PMI becomes a crucial factor in surgical decision-making. This study represents the first study demonstrating the validity of sarcopenia in all forms of GI cancer, thereby proposing surgical approaches to these tumors. Additionally, our investigation confirms the correlation between PMI and HGS, emphasizing this index's importance.
The limitations of this investigation may affect the results to some extent. For instance, despite the high statistical population, due to the limited availability of all variables required for evaluating the correlation in this study, the number of patients whose both PMI and length of stay in the hospital were investigated was restricted, which can undermine the statistical power of the analysis and challenge the comprehensiveness of these statistics in larger communities underscoring the requirement for more extensive studies. Furthermore, the length of hospitalization of postoperative patients can be influenced by previous underlying conditions and medications.
Future studies should aim to determine effectual and precise guidelines for retrieving sarcopenia, including physical therapy or dietary regimens in subjects affected with GI tumors. Additionally, identifying pharmacological agents with a minimal adverse impact on muscle mass during chemotherapy is suggested. In addition, for better practical use of PMI, a precise quantitative level as a cut-off of sarcopenia is highly recommended, which can be easily attended to in managing patients before surgery.
In conclusion, this study highlights the significance of the psoas muscle index (PMI) as a determinant factor for surgical outcomes in patients with GI cancers. PMI is easily obtainable and more precise than BMI and age in determining physical potency and hand grip strength, making this index a practical tool in preoperative assessments. These findings are essential in identifying high-risk patients and choosing proper approaches to enhance their life expectancy, especially considering surgical interventions' risk-benefit ratio.