Should pT2N+ Colorectal Cancer Be Downstaged from IIIA to IIA?

Abstract

Background/Aim: This study investigated the significance of lymph node metastasis (LNM) in patients with pT2 colorectal cancer (CRC). Patients and Methods: This retrospective cohort study was conducted at a high-volume cancer center in Japan and targeted all qualifying patients (n=617) with radically resected pT2 CRC. Subjects were stratified by the presence (LNM+) or absence (LNM–) of LNM to compare cancer-specific survival (CSS) and relapse-free survival (RFS) rates before and after propensity score matching. Results: There were 168 (27.2%) and 449 (72.8%) patients in the LNM+ and LNM− groups, respectively. Tumors in the LNM+ (vs. LNM–) group were more often less differentiated (Poor/Sig/Muc: 26.2% vs. 18.5%; p=0.035); more inclined to lymphatic (45.2% vs. 21.4%; p=0.000), vascular (64.9% vs. 44.8%; p=0.000), or neural (7.7% vs. 3.3%; p=0.019) invasion; and yielded more (≥12) harvested lymph nodes (94.0% vs. 85.5%; p=0.004). Although similar in terms of 5-year CSS (LNM–, 98.7%: LNM+, 95.8%; p=0.117), RFS in the LNM− (vs. LNM+) group was found to be significantly better (95.3% vs. 88.7%; p=0.003). After matching, RFS in the LNM− (vs. LNM+) group remained significantly better (95.4% vs. 88.7%; p=0.027). Recurrence was more likely in the LNM+ (vs. LNM–) group (pre-matching: 13.1% vs. 5.6%, p=0.002; post-matching: 12.4% vs. 5.2%, p=0.027), primarily occurring as liver metastases (pre-matching: 8.3% vs. 1.1%, p=0.002; post-matching: 7.8% vs. 1.3%, p=0.006). Conclusion: Lymph node metastasis does not affect CSS after radical resection of pT2 CRC, but vigilance for liver metastasis is essential. Downstaging of T2N+ CRC from stage IIIA to stage IIA is warranted.