Indications for neoadjuvant treatment based on risk factors for poor prognosis before and after neoadjuvant chemotherapy alone in patients with locally advanced rectal cancer

Introduction The oncological benefit of neoadjuvant chemotherapy (NAC) alone for locally advanced rectal cancer (LARC) remains controversial. The aim of this study was to clarify the clinical risk factors for poor prognosis before and after NAC for decision making regarding additional treatment in patients with LARC. Materials and methods We examined a total of 96 patients with MRI-defined poor-risk locally advanced mid-low rectal cancer treated by NAC alone between 2006 and 2018. Survival outcomes and clinical risk factors for poor prognosis before and after NAC were analyzed. Results In the median follow-up duration after surgery of 60 months (3–120), the rates of 5-year overall survival (OS), relapse-free survival (RFS), and local recurrence (LR) were 83.6%, 78.4%, and 8.2%, respectively. In the multivariate analyses, patients with cT4 disease had a significantly higher risk of poor OS (HR; 6.10, 95% CI; 1.32–28.15, P = 0.021) than those with cT3 disease. After NAC, ycN+ was significantly associated with a higher risk of poor OS (HR; 5.92, 95% CI; 1.27–27.62, P = 0.024) and RFS (HR; 2.55, 95% CI; 1.01–6.48, P = 0.048) than ycN-. In addition, patients with CEA after NAC (post-CEA) ≥ 5 ng/ml had a significantly higher risk LR (HR; 5.63, 95% CI; 1.06–29.93, P = 0.043). Conclusion NAC alone had an insufficient survival effect on patients with cT4 disease, ycN+, or an elevated post-CEA level. In contrast, NAC alone is a potential treatment for other patients with LARC.