Potential for Metastasis and Recurrence in Colorectal Carcinoma In Situ: A Retrospective Analysis of 1069 Patients

Background: Colorectal carcinoma in situ, characterized by cancer limited to the intramucosal layer or known as intraepithelial carcinoma, has conventionally considered to be without any risk of regional lymph node metastasis. However, isolated cases of regional lymph node metastasis, local recurrence, and distant metastasis challenge this assumption. This study aimed to assess the occurrence of regional lymph node metastasis and recurrence of colorectal carcinoma in situ. Methods: A retrospective analysis was conducted in 1069 patients who underwent full-thickness local excision or radical surgery for colorectal carcinoma in situ between January 1994 and December 2020. Histopathological features were assessed by 2 experienced pathologists. In cases of suspected recurrence, evaluation involved abdomen-pelvis and chest computed tomography, or PET-CT. Results: The recurrence rate of colorectal carcinoma in situ patients was 0.46%. Among the patients, 9 were diagnosed with regional lymph node metastasis or cancer recurrence. Of these, 4 patients were diagnosed with lymph node metastasis during primary surgery; 2 exhibited regional lymph node metastasis, and 2 presented with both regional and distant lymph node metastases. Regional lymph node metastasis occurred in additional 2 patients after radical surgery for the primary tumor. Distant metastasis was observed in 3 patients: hepatic metastasis in 1, hepatic and pulmonary metastases in another, and small bowel metastasis in the third patient. Among the 5 patients experiencing cancer recurrence, 1 expired due to cancer progression. Conclusion: Contrary to previous assumptions, colorectal carcinoma in situ can potentially metastasize to lymph nodes and recur. Therefore, careful assessment at the time of diagnosis is crucial, recognizing the possibility of lymph node metastasis or recurrence. This approach is essential for accurately identifying instances of cancer recurrence and ensuring optimal oncological outcomes.