Abstract
AIM: The tumor staging of colorectal cancer (CRC) plays a significant role in both treatment and prognosis, impacting surgical planning and adjuvant therapy decisions. Currently, the staging of CRC is based on the TNM system developed by the American Joint Committee on Cancer. Prior studies have suggested that survival rates and recurrent rates of T4a tumors appear to be worse than that of T4b tumors, although there is currently no consensus. Therefore, we collected patient data from Taichung Veterans General Hospital over the past decade in order to conduct further research. METHOD: Between 2010 and 2018, a total of 5760 newly diagnosed CRC patients were seen at the hospital. To eliminate the influence of any local lymph node involvement or distant organ metastasis on the research results, we focused on patients with pathologic Stage IIc disease (T4a-bN0M0). Patients with rectal cancer who had received neoadjuvant concurrent chemoradiotherapy were excluded. Ultimately, 132 patients were included in this study. A multivariate Cox regression analysis was conducted to identify independent risk factors for both 10-year cancer-specific survival (CSS) and overall survival (OS). RESULTS: A total of 132 patients were included in the study, with 90 classified as T4a and 42 as T4b. The 10-year CSS for pT4a and pT4b was 72.5% and 56.5%, respectively, with a p-value of 0.011. The 10-year OS for pT4a and pT4b was 48.4% and 42.5%, respectively, with a p-value of 0.086. There was no significant difference in the site of first recurrence between the pT4a and pT4b groups (p-value = 0.936). Overall, patients who received adjuvant chemotherapy therapy had a significantly better prognosis (p-value < 0.05). However, there was no significant difference in prognosis between oral 5-FU and FOLFOX. CONCLUSION: Based on our data, patients diagnosed with pathologic T4aN0M0 CRC appeared to experience a trend toward better 10-year OS when compared to those with T4bN0M0 disease, but this trend lacks statistical significance. Patients with locally advanced Stage II colon cancer clearly benefited from adjuvant chemotherapy therapy; therefore, FOLFOX may not necessarily be required.