The Chinese Guidelines for the Diagnosis and Treatment of Colorectal Cancer (2020 edition) recommend endoscopic resection, local excision, or segmental resection for early stage colon cancer (cT1N0M0). Endoscopic resection may be considered for superficial invasive cancers involving submucosal layer (SM1). Before deciding on endoscopic resection, careful evaluation of the tumor size, depth of invasion, tumor differentiation, and other relevant information is necessary. If preoperative endoscopic ultrasound indicates T1 or postoperative pathological examination confirms T1 with complete resection, negative margins (including the base), and favorable histological features (such as good differentiation and no vascular invasion), further surgical resection is not recommended, regardless of whether it is wide-based or pedunculated. If unfavorable histological features are present, or if the resection is incomplete with an inability to assess specimen margins due to fragmentation, additional segmental resection with regional lymph node dissection is recommended[4][8]9]. The two groups exhibited a statistically significant disparity in tumor diameter, indicating that the surgeons and gastroenterologists adhered strictly to the standards of their respective specialties.
In our center, except for one patient with a history of radical surgery for right-sided colon cancer who underwent open radical resection for sigmoid colon cancer, the remaining 32 patients underwent laparoscopic surgery combined with colonoscopy during the procedure. This approach not only allows for precise localization but also enables re-evaluation (except for multiple primary cancers). One patient had five polyps removed using the snare technique during colonoscopy, and the pathological report revealed a tubular adenocarcinoma with moderate differentiation at the descending colorectal junction. During the salvage procedure, two tumors were identified via colonoscopy, and postoperative pathology indicated two foci of colon cancer in the left half of the colon.
Kyong et al. conducted a retrospective analysis of 745 patients with T1 stage colorectal cancer who underwent endoscopic resection or surgical procedures. Among them, 91 patients (12.2%) had regional lymph node metastases. Univariate and multivariate analyses indicated that deep submucosal infiltration, high histological grade (poor differentiation, mucinous adenocarcinoma, signet ring cell carcinoma, and neuroendocrine carcinoma), tumor budding G3, and vascular invasion were high-risk factors for regional lymph node metastasis in T1 stage colorectal cancer. Among patients with one, two, three, or four high-risk factors, the proportions of regional lymph node metastasis were 6.0%, 18.7%, 36.4%, and 100%, respectively[10]. Additionally, as the polyp size increased, the risk of lymph node infiltration and distant metastasis significantly increased, especially when the polyp diameter exceeded 2 cm. This is similar to the findings for early gastric adenocarcinoma[20]. Among the 17 patients in group A, four patients had two high-risk factors, and three patients had three high-risk factors. However, owing to the small sample size and tumor diameter, only one patient with one high-risk factor had lymph node metastasis (2/3). Furthermore, although the mechanism is not yet clear, the NCCN guidelines recommend that the number of lymph nodes detected should reach or exceed 12, as this criterion is associated with prolonged patient survival and accurate staging. Even if lymph nodes are negative, the detection of fewer than 12 lymph nodes should be considered a high-risk factor affecting patient survival[1]. Considering the lymph node detection rate in this study, especially in group A, close cooperation between clinicians and pathologists is necessary in clinical practice to accurately stage the disease and provide a basis for subsequent treatment strategies.
Ki-67 is a proliferative antigen. It is expressed in all phases of the cell growth cycle except for the G0 phase. This specific immune reaction is associated with tumor proliferation. High expression of the Ki-67 antigen has been shown to have prognostic significance[11]. Randomized controlled studies have found that high expression of Ki-67 (≥ 40%) is an independent predictor of reduced relapse-free survival (RFS) in colon cancer[12]. The median Ki-67 value in the entire patient group was 80%, with a majority exceeding 90%. Therefore, in terms of local recurrence, Ki-67 has a reference value for the subsequent treatment of early stage cancer with high-risk factors.
After salvage surgery, there were 3 cases of residual carcinoma of adverse pathological types, specifically deep infiltration beneath the mucosa, which affected the positive vertical margin of endoscopic resection. In one case, postoperative pathology revealed primary carcinomas in the descending and sigmoid colon, known as synchronous colorectal cancer, which is more commonly found in the right half of the colon [13]. The proportion of microsatellite instability is higher in this type of colorectal cancer patients compared to those with isolated colorectal cancer. Owing to the difficulty of detecting small tumors with early staging, the importance of preoperative colonoscopy has been emphasized [14].
During the data screening phase, 4 patients with high-risk factors for recurrence did not undergo salvage surgery. Among them, one patient opted for adjuvant radiotherapy because of a strong desire for sphincter preservation, and long-term follow-up showed no local recurrence. A multicenter randomized controlled trial initiated by Borstlap et al. included 302 patients with intermediate-risk early rectal cancer, including tumors with a diameter between 3–5 cm, or tumors with a diameter less than 3 cm and poor differentiation (with or without vascular or lymphatic invasion) in T1 stage patients, as well as T2 stage patients with high or moderate differentiation, no vascular or lymphatic invasion, and tumors with a diameter less than 3 cm. The patients underwent local curative surgery (including TEM, ESD, and EMR) and were randomly assigned to receive adjuvant chemoradiotherapy (experimental group) or TME (control group). The results showed that for intermediate-risk early rectal cancer patients who underwent curative resection through endoscopic or transanal surgery, if faced with clinical decision difficulties regarding subsequent conventional curative surgery, adjuvant chemoradiotherapy is a safe treatment strategy in terms of oncology [15][16]. Long-term follow-up studies have also confirmed that among early (cT1-3N0M0) colorectal cancer patients who received adjuvant chemoradiotherapy after local treatment, approximately 2/3 had good long-term oncological outcomes and health-related quality of life (HRQoL) [17][18]. However, for high-risk patients with deep submucosal invasion and vascular or lymphatic invasion, curative surgical resection is still recommended [19].
This article describes a descriptive case study that retrospectively collected relevant cases from a single center. The number of cases was small and scattered and the overall prognosis was good. This study provided preliminary evidence regarding the necessity and indications for salvage surgery and perioperative management.