Purpose: Because of the adverse consequences of radical resection of T2 colorectal cancer, criteria are needed for selection of patients who can safely undergo local excision without requiring additional radical surgery. We therefore conducted a retrospective study of patients with T2 colorectal cancer to identify risk factors for nodal involvement that might be used in selecting patients for local excision.
Methods: We reviewed records from consecutive patients who had undergone curative resection of T2 colorectal cancer at the Department of Surgery, National Defense Medical College, Saitama, Japan, between 1985 and 2005. Data on conventional clinicopathologic variables were retrieved from pathology reports at the time of surgery, and archived slides were evaluated regarding potential risk factors such as extent of poorly differentiated component (grade I-III), myxoid cancer stroma, tumor budding, and growth pattern and invasion depth in the muscularis propria.
Results: A total of 244 patients (139 men and 105 women) treated for T2 colorectal cancer were included. Nodal involvement was found in 7 (8.4%) of 83 patients classified as grade I on the poorly differentiated component vs. 47 (29.2%) of 161 patients classified as grade II or III (P < .001). Of 148 patients negative for myxoid cancer stroma, 30 (16.9%) had nodal involvement vs. 24 (36.4%) of 42 patients who were positive for myxoid cancer stroma (P = .0011). According to multiple variable logistic analysis, significant independent risk factors for nodal involvement included poorly differentiated component (P = .002), myxoid cancer stroma (P = .032), and lymphovascular invasion (P = .022).
Conclusions: Poorly differentiated component, myxoid cancer stroma, and lymphovascular invasion are significant independent risk factors for nodal involvement in T2 colorectal cancer. We need further study to validate these results on another data set, especially in patients with rectal cancer, and to confirm whether local resection of T2 rectal cancer is able to predict the nodal involvement before laparotomy.