ObjectiveCRC patients with sarcopenia often have a poor prognosis, and the timing for preoperative intervention to improve sarcopenia is unclear. Sarcopenia can affect the body's overall inflammatory status. This study aims to investigate whether sarcopenia exacerbates the inflammatory response in colorectal cancer patients following surgical stimulation, and consequently, its impact on their prognosis. MethodA retrospective analysis was conducted on a cohort of 215 CRC patients, who were categorized into either a sarcopenia group or a non-sarcopenia group based on their Skeletal Muscle Index (SMI) values. Inflammation-related indicators were collected from patients both before and after surgery, allowing for the calculation of the differences in preoperative and postoperative changes. The correlation between inflammatory markers and postoperative complications was also assessed. All patients were followed up for a period ranging from 2 to 5 years, with an average follow-up duration of 3 years, during which their recurrence and mortality rates were recorded. Additionally, the relationship between inflammation indicators was explored. Results45 out of 215 patients with sarcopenia had higher levels of preoperative baseline inflammation markers such as CRP (P=0.002), IBI (P<0.001), SIRI (P=0.009), and SII (P=0.002) compared to non-sarcopenia patients. There was a significant difference in inflammatory indicators before and after surgery between dIBI, dSIRI, and dSII, with the largest effect observed. Additionally, the predictive capabilities of dIBI, dSIRI, and dSII on postoperative complications, as measured by AUROC, were found to be 0.938, 0.877, and 0.818 respectively. Furthermore, survival analysis indicated that dIBI, dSIRI,and dSII were all effective in predicting long-term postoperative mortality in patients. ConclusionThe findings suggest sarcopenia plays a significant role in exacerbating postoperative inflammatory response in CRC patients, leading to an increased risk of postoperative complications and influencing long-term survival outcomes.