The role of adjuvant chemotherapy (adj-CT) in stage II colon cancer remains controversial. Circulating tumor DNA (ctDNA) is a promising biomarker for detecting minimal residual disease (MRD) and predicting recurrence. This systematic review and meta-analysis evaluated the prognostic value of ctDNA in stage II colorectal cancer (CRC), focusing on postoperative detection, post adj-CT outcomes, and dynamic surveillance. A literature search identified studies correlating ctDNA positivity in stage II CRC with recurrence risk, recurrence-free survival (RFS), and disease-free survival (DFS). Seven studies met the inclusion criteria. Postoperative ctDNA positivity significantly increased the risk of recurrence (pooled risk ratio [RR:] 3.66; 95% confidence interval [CI]: 1.25–10.72; p = 0.002). CtDNA positivity after adj-CT was strongly associated with poor survival, while dynamic ctDNA monitoring detected recurrence earlier than conventional methods, including carcinoembryonic antigen (CEA) and imaging. CtDNA is a robust prognostic biomarker in stage II CRC, enabling personalized treatment. High-risk ctDNA-positive patients may benefit from intensified therapy, while ctDNA-negative patients could avoid unnecessary treatments. However, the standardization of detection methods and large-scale validation studies are needed before integrating ctDNA into routine clinical practice as a non-invasive, dynamic tool for personalized care.

Local Excision (LE) or Watch and Wait (WW) for patients with complete clinical response or near-complete clinical response after neoadjuvant chemoradiotherapy (nCRT) were proposed to avoid morbidity and impairment of quality of life after rectal resection. The aim of this study is to perform a systematic review of the literature, and to compare rectal-sparing approaches, in terms of rectum-preservation rate, local control, and distant recurrences. A systematic review and meta-analysis were performed of studies published until July 2022 (PROSPERO, registration CRD42022341480), and the quality of evidence was assessed using a GRADE approach. Seven retrospective studies and one prospective trial were included. In six studies, patients were treated with standard long-course nCRT, and in two with Total Neoadjuvant Therapy (TNT). Overall, there were 213 and 188 patients in WW and LE group, respectively, and no difference was found between WW and LE when considering rectum-preservation rate (OR 0.80 95%CI 0.31–2.01, p = 0.63), local disease (OR 1.60 95%CI 0.75–3.42, p = 0.22), locoregional failure (OR 0.85 95%CI 0.20–3.66, p = 0.83) and distant recurrence (OR 0.76 95%CI 0.37–1.55, p = 0.45). Studies directly comparing WW and LE are still lacking, even though no differences between WW and LE in terms of rectum-preservation, local control, and distant recurrences have been found.

Background: Rectal-sparing approaches for patients with rectal cancer who achieved a complete or major response following neoadjuvant therapy constitute a paradigm of a potential shift in the management of patients with rectal cancer; however, their role remains controversial. The aim of this study was to investigate the feasibility of rectal-sparing approaches to preserve the rectum without impairing the outcomes. Methods: This prospective, multicenter, observational study investigated the outcomes of patients with clinical stage II–III mid-low rectal adenocarcinoma treated with any neoadjuvant therapy, and either transanal local excision or watch-and-wait approach, based on tumor response (major or complete) and patient/surgeon choice. The primary endpoint of the study was rectum preservation at a minimum follow-up of 2 years. Secondary endpoints were overall, disease-free, local and distant recurrence-free, and stoma-free survival at 3 years. Results: Of the 178 patients enrolled in 16 centers, 112 (62.9%) were managed with local excision and 66 (37.1%) with watch-and-wait. At a median (interquartile range) follow-up of 36.1 (30.6–45.6) months, the rectum was preserved in 144 (80.9%) patients. The 3-year rectum-sparing, overall survival, disease-free survival, local recurrence-free survival, and distant recurrence-free survival was 80.6% (95% CI 73.9–85.8), 97.6% (95% CI 93.6–99.1), 90.0% (95% CI 84.3–93.7), 94.7% (95% CI 90.1–97.2), and 94.6% (95% CI 89.9–97.2), respectively. The 3-year stoma-free survival was 95.0% (95% CI 89.5–97.6). The 3-year regrowth-free survival in the watch-and-wait group was 71.8% (95% CI 59.9–81.2). Conclusions: In rectal cancer patients with major or complete clinical response after neoadjuvant therapy, the rectum can be preserved in about 80% of cases, without compromising the outcomes.