Published online Apr 16, 2024. doi: 10.4253/wjge.v16.i4.193
Peer-review started: November 29, 2023
First decision: December 27, 2023
Revised: January 28, 2024
Accepted: March 18, 2024
Article in press: March 18, 2024
Published online: April 16, 2024
The incidence of malignant colorectal polyps is increasing with the introduction of colorectal screening programs. Even with the application of optical diagnostic tools, many of these lesions are diagnosed only after endoscopic polyp removal. Submucosal invasion that is already present by this time can result in lymphovascular invasion and metastasis formation. Choosing the management strategy (completion surgery vs surveillance only) is mainly based on histological prognostic factors.
Suboptimal reporting of prognostic histological features might lead to inadequate post-polypectomy management choice (including both over-treatment resulting in unnecessary bowel resection and under-treatment leading to an increased risk of disease recurrence and dissemination). The decision over post-polypectomy management is further complicated by the fact that evidence about long-term outcomes of a surveillance-only strategy is limited.
This study aimed to assess the long-term outcomes of endoscopic removal of malignant colorectal polyps by comparing local and distant recurrence rates between the two post-polypectomy management strategies (completion surgery and surveillance-only strategy). We also assessed the residual malignancy and lymph node involvement rate after secondary surgery as well as the adequacy of reporting of post-polypectomy prognostic histological features and investigated the adherence to post-polypectomy surveillance colonoscopies.
A retrospective cohort study over a 10-year study period was conducted. Residual disease rate and nodal metastases after secondary surgery and local and distant recurrence rates for those with at least 1 year of follow-up were investigated. The relatively longer follow-up period in our study compared to previous reports allowed for adequate assessment of adverse outcomes.
Reporting of high-risk histological features varies greatly. While tumor differentiation was reported in almost 90% of cases, budding was only reported in 25% of cases. The residual malignancy and lymph node involvement rates were 25% and 10%, respectively, but could only be detected in surgical specimens after R1 endoscopic resection. The long-term post-polypectomy adverse outcome rate was 9.0%, which was somewhat elevated compared to previously reported rates. Secondary surgery for completion after endoscopic polypectomy did not affect the occurrence of adverse outcomes. Adherence to surveillance colonoscopy was low with only half of the patients presenting at the 1-year follow-up.
Reporting of high-risk features is often inadequate to serve as a basis for the decision of the optimal management strategy and needs to be improved. The definition of a positive resection margin after endoscopic resection needs to be reconsidered, as residual malignancy and lymph node involvement were found only in surgical specimens after R1 endoscopic resection. The relatively higher long-term adverse outcome rate draws attention to the importance of adequate prepolypectomy assessment and implementation of advanced polypectomy techniques. Tumor markers cannot serve as a basis of adverse outcome prediction. Improving adherence to surveillance colonoscopy is essential.
There is a pressing need for further, long-term, multicentric studies considering optimal timing and participation rate of surveillance examination. Our study mainly focused on sporadic malignant colorectal polyps, but any potential differences between adverse outcomes of hereditary and sporadic lesions might further be investigated.