Front Oncol: The relationship between preoperative radiotherapy (RT) and CEA level before treatment with the prognosis of patients with locally advanced rectal cancer (LARC)

Preoperative radiotherapy, whether it is long course radiotherapy (LCRT) or short course radiotherapy (SCRT), is the standard neoadjuvant treatment strategy for the treatment of locally advanced rectal cancer (LARC)
.
However, whether it is LCRT or SCRT, the long-term survival benefits of preoperative radiotherapy are still controversial
.
Carcinoembryonic antigen (CEA) is a routine screening and diagnostic index for colorectal cancer, and it is a widely used monitoring marker for postoperative recurrence of colorectal cancer
.
However, there is no report about the use of CEA to guide the long-term clinical prognosis management of preoperative radiotherapy
.
Recently, the team from the Cancer Hospital of Fujian Medical University used the SEER database to assess the long-term survival benefits of preoperative radiotherapy for locally advanced rectal cancer (LARC), and to determine the relationship between the preoperative CEA level and prognosis of patients undergoing preoperative radiotherapy
.
The results were published in Frontiers in Oncology
.

The study collected relevant data of LARC patients diagnosed from 2011 to 2015 in the SEER database, and divided them into surgical treatment group (S) and preoperative radiotherapy continuous surgical treatment group ((RT+S) according to the inclusion criteria
.
The main result is cancer specificity.
Survival rate (CSS) and cancer-specific mortality (CSM).

CSS was evaluated by Kaplan-Meier analysis, and CSM was evaluated by competitive risk model
.
Subgroup analysis was stratified according to the level of CEA before treatment
.

A total of 2760 patients were eligible, including 350 (12.
7%) in S group and 2410 (87.
3%) in RT+S group
.
In short, the proportion of men in the RT+S group, increased CEA, LND<12, and T3 were higher than those in the S group (all p<0.
05)
.
The rates of tumor differentiation grade III/IV, TD, PNI, stage III and N1/2 in the RT+S group were lower than those in the S group (all p <0.
05)
.
However, after the 1:1 propensity score matching, the baseline characteristics between the two groups are comparable (all p ≥ 0.
05)
.

Before PSM, the 1, 3, and 4-year CSS of the RT+S and S groups were 98.
02% vs.
95.
78% (p=0.
078); 90.
63% vs.
87.
51% (p=0.
224) and 84.
57% vs.
82.
94%, respectively (P=0.
374)
.
After PSM, the 1, 3, and 4-year CSS of the RT+S and S groups were 97.
94% vs.
96.
27% (p = P=0.
203); 93.
58% vs.
88.
64% (p = 0.
134) and 88.
36% vs.
83.
68% (p = 0.
279)
.
There was no statistical difference before and after PSM
.

CSS before and after PSM

Before PSM, the 1, 3, and 4-year CSM of the two groups were 1.
97% vs.
4.
20% (p = 0.
068); 9.
21% vs.
12.
28% (p = 0.
189); 15.
03% vs.
16.
61% (p=0.
364)
.
After PSM, the 1, 3 and 4-year CSM of the two groups were 2.
05% vs.
3.
72% (p=0.
194); 6.
38% vs.
11.
18% (p=0.
110); 11.
53% vs.
15.
88% (p = 0.
255)
.
There was no statistical difference before and after PSM
.

CSM before and after PSM

In the matched cohort, 420 patients had normal CEA levels, including 213 patients in the S group and 207 patients in the RT+S group
.
In terms of baseline characteristics, there was no significant difference between the S group and the RT+S group (all p≥0.
05)
.
KM survival analysis showed that the median CSS difference between the two groups was not statistically significant (HR = 0.
73, 95% CI = 0.
30 1.
77, p = 0.
490)
.
Similar results were found in CSM (HR = 0.
74, 95% CI = 0.
31 1.
78, p = 0.
500)
.

The impact of CEA level on CSS after PSM

In the matched cohort, 242 patients had elevated CEA levels before treatment, including 118 in the S group and 124 in the RT+S group
.
Similarly, in terms of baseline characteristics, no significant difference was observed between the S group and the RT+S group (all p ≥0.
05)
.
The median CSS of the RT + S group was better than that of the S group (HR = 0.
41, 95% CI 0.
92 = 0.
18, p = 0.
032).
Similarly, the CSS rate of 1, 3 and 4 years was also higher than that of the S group (97.
12% vs 93.
22%) , 90.
24% vs 79.
79% and 84.
91% vs 63.
51%)
.
Similarly, the median CSM of the RT + S group was better than that of the S group (HR = 0.
42, 95% CI = 0.
19-0.
94, p = 0.
032; Figure 4 b)
.

The effect of CEA level after PSM on CSM

In addition, a multivariate analysis of the subgroup with elevated CEA showed that preoperative radiotherapy was an independent protective factor for CSS and CSM (CSS: HR = 0.
36, 95% CI = 0.
15 0.
83, p = 0.
017; CSM: HR = 0.
41, 95% CI = 0.
18 0.
94, p = 0.
036)
.

Factors related to CSS and CSM in patients with elevated CEA

In summary, studies have shown that the level of CEA before treatment is considered a potential marker for screening LARC patients who have obtained long-term survival from preoperative radiotherapy
.

Original source:

Wang L, Zhong X, Lin H, Shao L, Chen G and Wu J (2021) The Correlation Between Survival Benefit of Preoperative Radiotherapy and Pretreatment Carcinoembryonic Antigen Level in Locally Advanced Rectal Cancer.
Front.
Oncol.
11:735882.
doi: 10.
3389 /fonc.
2021.
735882