Published online Nov 28, 2020. doi: 10.3748/wjg.v26.i44.7022
Peer-review started: August 6, 2020
First decision: October 18, 2020
Revised: October 31, 2020
Accepted: November 13, 2020
Article in press: November 13, 2020
Published online: November 28, 2020
Preoperative chemoradiotherapy (CRT) is a standard treatment modality for locally advanced rectal cancer. Although advances in CRT and surgical treatment have helped achieve better outcomes for rectal cancer, the overall survival of patients remains an issue. Moreover, the response to CRT varies from pathologic complete response to disease progression. As preoperative CRT is a time-consuming modality, it is important to determine the predictive factors for treatment response to preoperative CRT.
Carcinoembryonic antigen (CEA) has been reported to be an important surveillance biomarker for colorectal cancer. Although various biomolecular or immune-molecular markers have been recently introduced, they are unable to show sufficiency for clinical application or cost-effectiveness. If we can prove the relationship between changes in CEA levels before and after chemoradiotherapy and the response to CRT for rectal cancer, we can provide personalized treatment for each patient with rectal cancer to ensure a better prognosis.
This study aimed to identify patients with locally advanced rectal cancer eligible for preoperative CRT according to changes in CEA levels before and after preoperative CRT.
We included 145 patients with locally advanced rectal cancer who underwent preoperative CRT and curative resection. Patients were assigned to three groups according to pre- and post-CRT serum CEA levels: both > 5; pre > 5 and post ≤ 5; and both ≤ 5 ng/mL, respectively. We compared the response to CRT depending on changes in serum CEA levels between the groups. Multivariate logistic regression analysis was used to evaluate the prognostic factors for pathologic complete response/good response.
There were 27, 43, and 65 patients in groups A, B, and C, respectively, according to changes in serum CEA levels before and after CRT. Pre-CRT (P < 0.001) and post-CRT (P < 0.001) CEA levels and the ratio of down-staging (P = 0.013) were higher in Groups B and C than in Group A. The ratio of pathologic tumor regression grade 0/1 significantly differed among the groups (P = 0.003). Group C had the highest number of patients showing pathologic complete response (pCR; P < 0.001). Most patients with pCR showed pre- and post-CRT CEA levels of < 5 ng/mL (P < 0.001, P = 0.008). Pre- and post-CRT CEA levels were important risk factors for pCR (odds ratio 18.71; 95% confidence interval 4.62–129.51, P < 0.001) and good response (odds ratio 5.07; 95% confidence interval 1.92–14.83, P = 0.002). Pre-CRT neutrophil-to-lymphocyte ratio and post-CRT T ≥ 3 stage were also prognostic factors for pCR or good response.
Pre- and post-CRT CEA levels as well as changes in CEA levels were prognostic markers for the response to CRT and may facilitate treatment individualization for rectal cancer.
Pretreatment clinical factors such as lymphocyte counts and pre- and post-treatment CEA levels are important markers that predict the response to CRT for locally advanced rectal cancer. These clinical factors may facilitate the development of individualized treatment strategies for advanced rectal cancer.