Purpose: The role of local excision for pT2 distal rectal cancer has been challenged due to the observation of high rates of lymph node metastases and local failure. However, neoadjuvant chemoradiation (CRT) therapy for distal rectal cancer has led to increased local disease control and significant tumor downstaging, possibly decreasing rates of lymph node metastases. In this setting, a possible role for local excision of ypT2 has been suggested.
Methods: 289 patients with incomplete clinical response were managed by radical surgery. Patients with final pathological stage ypT2 were compared to ypT0-4 to determine the risk of unfavorable pathological features that could represent unacceptable risk for local failure after local excision. Also, patients with ypT2 were studied to determine those with increased risk for lymph node metastases.
Results: 88 (30%) patients had ypT2 rectal cancer. Final ypT status did not correlate with pre-treatment radiological staging (p=0.62). ypT status was significantly associated with the risk of lymph node metastases (p=0.001), risk of perineural and vascular invasion (p<0.001), and recurrence (p=0.001). Patients with ypT2 rectal cancer had 19% of lymph node metastases. Lymph node metastases in ypT2 was associated with perineural invasion (47% vs 4%; p=0.000), vascular Invasion (59% vs 6%; p=0.001) and decreased mean interval CRT-surgery (12wk vs 18wk;p=0.001) but not with mean tumor size (3.2 vs 3.1cm; p=0.8). Disease-free and overall survival rates were significantly better for patients with ypT2N0 (p=0.02 and p=0.006 respectively) when compared to ypT2N+ after a mean follow-up of 57 months. 55 (62.5%) patients with ypT2 had at least one unfavorable pathological feature for local excision (lymph node metastases, vascular or perineural invasion, mucinous type or tumor size > 3cm).
Conclusions: Lymph node metastasis was present in a considerably high proportion of patients with ypT2 and was significantly associated with poor survival rates. The risk of lymph node metastases could not be predicted by radiological pre-treatment staging or tumor size. Radical surgery should be considered the standard treatment option for ypT2 rectal cancer following CRT.