Close margin of adverse histologic factors with a negative primary tumor margin is not associated with increased locoregional recurrence in colon cancer

Purpose: Locoregional recurrence after resection of colon cancer is increased when primary tumor margin is positive (<1 ​mm). Data is limited regarding the risk of locoregional recurrence with close margin (<1 ​mm) of histologic factors, such as intravascular tumor, intranodal tumor, tumor deposits, or extranodal extension. We hypothesized that close margin of these factors doesn't affect locoregional recurrence.

Methods: A retrospective review of all colon cancer surgical resections for adenocarcinoma from 2007 to 2020 was performed. Inclusion criteria were specimens with a negative primary tumor margin but a close margin of adverse histologic factors, defined as intravascular tumor, intranodal tumor, tumor deposits, or extranodal extension within 1 ​mm of a mesenteric or circumferential margin.

Results: Among 4435 pathology reports reviewed, 45 (1 ​%) of cases met inclusion criteria. Average follow-up was 38 months. The adverse histologic factor was identified as intranodal tumor in 24 (53 ​%) cases, intravascular tumor in 8 (17.8 ​%), tumor deposits in 5 (11.1 ​%), and more than one pathologic feature in 6 (13.3 ​%). There were 9 (20 ​%) recurrences; 6 (13 ​%) had distant recurrences only, 2 (4 ​%) patients had locoregional recurrences only, and 1 (2 ​%) patient had both locoregional and distant recurrence. The adverse histologic factor in these three patients was intravascular in two and both intravascular and intranodal in one.

Conclusion: Based on our results, we do not have evidence that the presence of intravascular tumor, intranodal tumor, tumor deposits, or extranodal extension within 1 ​mm of a mesenteric or circumferential margin is associated with increased risk of locoregional recurrence.