Postoperative Energy and Protein Intake Attainment After Elective Laparoscopic Colorectal Cancer Surgery

Surgery is the mainstay of curative treatment for colorectal cancer, and early oral intake is a core element of every ERAS pathway. Adherence to the nutrition element is nonetheless the least audited part of the bundle. In a Canadian academic centre, patients on an ERAS pathway consumed approximately 0.54 g/kg/day of protein in the first three postoperative days, with only about 36 percent meeting the protein target; the corresponding figures under conventional care were 0.33 g/kg/day and 22 percent. The 2025 ESPEN surgical nutrition guideline recommends 25 to 30 kcal/kg/day and 1.2 to 1.5 g/kg/day of protein, with supplemental parenteral nutrition when less than 60 percent of target is reached by 48 to 72 hours in high-risk patients, and the 2025 ERAS Society colorectal guideline recommends 25 kcal/kg/day and 1.5 g/kg/day of protein together with routine daily monitoring of intake. No comparable quantification exists for Chinese colorectal ERAS programmes. This study is a single-centre, prospective, observational cohort with consecutive sampling. Adults scheduled for elective laparoscopic radical resection of colorectal cancer are eligible. All patients receive the standard institutional ERAS pathway, including a protocolised postoperative oral intake schedule; no nutritional intervention is assigned by the study, and all enteral or parenteral nutrition are prescribed by the treating team and recorded as observed. Daily intake was assessed using either the 24-hour dietary recall method or the dietary record method (bookkeeping method). The dietary record method (bookkeeping method) was adopted for patients whose family members could cooperate with the recording. For patients unable to complete dietary recording, daily intake was measured by 24-hour recall, supplemented by visual plate-waste estimation and information from nursing and family caregivers. Energy and protein intake were subsequently calculated using the Chinese Food Composition Tables and product labels. Targets are calculated from admission body weight, with adjusted body weight for patients with a body mass index of 28 or above. The primary outcome is the proportion of patients reaching at least 60 percent of the energy target on postoperative day 5 or at discharge. Secondary outcomes cover daily attainment, process indicators such as time to first oral fluid, first flatus and first bowel movement, resumption of oral intake within 24 hours and supplement prescription and consumption, gastrointestinal tolerance measured by the I-FEED and feeding intolerance scores, agreement between an objective intake grading and the original descriptive intake item, structured patient-level and clinician-level barriers, and clinical outcomes including gastrointestinal recovery, length of stay, 30-day complications, postoperative serum albumin, the interval to initiation of the first postoperative anti-tumour therapy and body weight loss at 3 months. A total of 360 consecutive patients will be enrolled and followed. The sample size is determined by the precision required for the primary outcome, which is a single proportion estimated in the whole cohort rather than a between-group comparison. Published ERAS cohorts show mean postoperative intakes well below prescription, with only a minority of patients reaching 60% of energy requirements during the first three postoperative days[4, 10]. The investigators accordingly assumed p = 0.50, the value that maximises variance and therefore yields the most conservative sample size, with a two-sided 95% confidence interval. A permissible error of 5 percentage points requires 384 patients; the protocol enrols 360, which gives a half-width of 5.2 percentage points and was accepted as the operating precision. Recruitment is consecutive and continues until 360 patients have completed the primary assessment, so that post-enrolment exclusions do not erode the final sample. The two age cohorts will not be of equal size. Based on the age distribution of consecutively admitted patients, approximately two thirds are expected to be aged 60 years or older, giving roughly 240 patients in the older cohort and 120 in the younger cohort. A cohort of about 120 patients yields a half-width of approximately 8.9 percentage points for the cohort-specific proportion. With this allocation, the study has 78% power at a two-sided α of 0.05 to detect an absolute difference of 15 percentage points between age cohorts, and 95% power to detect a difference of 20 percentage points. The primary analysis is performed on the whole cohort; the age-stratified comparison is a prespecified secondary analysis and is not powered as a primary endpoint.