Colorectal Surgery

Perioperative immunonutrition modestly reduces minor infectious complications after colorectal cancer resection

This systematic review and meta-analysis included 10 perioperative immunonutrition studies in colorectal cancer resection, half randomized controlled trials. Immunonutrition significantly reduced minor infectious complications (RR 0.67; 95% CI, 0.51-0.89), without clear effect on overall infectious events. There was no observed benefit for noninfectious complications or length of stay. Higher doses of immunonutrition were consistently associated with greater reductions in infection risk, suggesting a dose–response relationship. Methodologic heterogeneity and small sample sizes limit firm recommendations but support considering higher-dose formulas in high-risk patients. 1

MRI tumor deposits identify high-risk pCR rectal cancer patients without adjuvant therapy benefit

In this multicenter cohort of 384 rectal cancer patients with pathologic complete response after neoadjuvant therapy, pretreatment MRI markers were evaluated. Presence of MRI-detected tumor deposits (mrTD+) conferred a five-fold higher recurrence risk (HR 5.16; 95% CI, 2.67-9.97). mrTD+ patients had markedly worse 3-year DFS (74.5% vs 96.6%) and 5-year OS (83.6% vs 98.6%) than mrTD- patients. Adjuvant therapy did not improve prognosis in any MRI-defined subgroup, including mrTD+ patients. These findings support using mrTD to stratify surveillance intensity rather than to select for adjuvant chemotherapy in pCR rectal cancer. 2

Tumor-informed WGS ctDNA tracking supports watch-and-wait selection in locally advanced rectal cancer

This study used a primary-tumor-informed whole-genome sequencing assay to monitor ctDNA in locally advanced rectal cancer across treatment phases. ctDNA was detectable at baseline in 95% of patients, and higher baseline tumor fraction predicted lower chances of sustained clinical complete response. Persistently high or rising tumor fraction during or after neoadjuvant therapy was associated with higher relapse risk. Very low tumor fraction during surveillance occurred in many non-recurrent patients, suggesting minimal residual ctDNA can persist without overt disease. These results support ctDNA dynamics as a tool for selecting and monitoring watch-and-wait candidates, while highlighting current specificity limitations. 3

ENCODER exosome-based liquid biopsy accurately detects early-onset colorectal cancer

The ENCODER multicenter study evaluated a six-biomarker exosome/cell-free RNA panel in 542 individuals for early-onset colorectal cancer detection. Using machine learning, the assay achieved AUROC 97.5% in training and 95.6% in an independent testing cohort. In the testing cohort, overall sensitivity was 91.6% with 87.5% specificity; stage I–III cancers had 97.3% sensitivity. Sensitivity for premalignant high-grade dysplasia lesions was lower at 61.5%. Biomarker levels fell rapidly after surgery, reaching negativity by day 4, suggesting potential utility for postoperative monitoring in young patients. 4