Colonic Conditions: Locally Advanced Colon Cancer

Locally advanced colon cancers represent a small, but distinct subset of colorectal neoplasms. The American Joint Committee on Cancer Eighth Edition (Weiser, MR. AJCC 8th Edition: 2018) Staging Manual defines “locally advanced” colon cancers as those that either invade the visceral peritoneum (T4a) or those that invade adjacent structures (T4b). Although both subsets are thought to be “high risk” for local recurrence, the recurrence patterns are suspected to be different, with T4a tumors at higher risk for disseminated intraperitoneal spread, and T4b neoplasms at risk for in situ, localized recurrence or persistence. Both categories do require consideration of adjuvant chemotherapy even if node negative, but those that invade adjacent structures create special technical challenges that require accurate preoperative localization of invaded structures when possible, identification of participating multispecialty teams, and consideration of nonstandard uses of chemotherapy and radiation in the neoadjuvant or adjuvant setting. Approaching these tumors with intent-to-cure is possible. Premeditation of local involvement is important, sets patient and provider expectations, and may improve opportunities for R0 resection.