Factors associated with complete clinical response after neoadjuvant therapy in locally advanced rectal cancer: A Mexican retrospective study

Table 1 Clinical, tumor, and neoadjuvant treatment characteristics of the overall cohort (n = 101)

Characteristic	Value
Age (years), mean ± SD (range)	61.7 ± 13.3 (23-85)
Sex
Male	55 (54.5)
Female	46 (45.5)
Clinical stage
II	19 (18.8)
III	82 (81.2)
Tumor size (cm)	7.28 ± 2.52
< 5	22 (21.8)
≥ 5	79 (78.2)
Tumor location
Lower rectum	40 (39.6)
Middle rectum	39 (38.6)
Upper rectum	22 (21.8)
Distance from anal verge (cm)	6.91 ± 3.74
Hemoglobin < 10 g/dL	34 (33.7)
CEA ≥ 5 ng/mL	50 (49.5)
Albumin (g/dL)	4.0 ± 0.59
Leukocytes (× 103/μL)	7.28 ± 5.03
Neoadjuvant radiotherapy	101 (100)
Neoadjuvant chemotherapy
Yes	82 (81.2)
No	19 (18.8)
Complete response	20 (19.8)

Data were showed as mean ± SD or n (%). Complete response is reported descriptively and defined as complete clinical response managed with watch-and-wait or pathological complete response confirmed after surgery. Inferential analyses in this study were focused on complete clinical response. CEA: Carcinoembryonic antigen.

Table 2 Patients achieving complete response after neoadjuvant (n = 20)

Variable	Value
Age (years)	61.6 ± 12.9
Sex
Male	12 (60.0)
Female	8 (40.0)
ECOG performance status
0	11 (55.0)
1	8 (40.0)
≥ 2	1 (5.0)
Distance from anal verge (cm)	5.0 (1.5-6.3)
Tumor length (cm)	5.8 ± 2.4
Baseline CEA (ng/mL)	3.2 (1.8-6.4)
Post-neoadjuvant CEA (ng/mL)	1.9 ± 0.8
Clinical T stage
≥ T3	17 (85.0)
≤ T2	3 (15.0)
Clinical N stage
Positive	14 (70.0)
Negative	6 (30.0)
Radiotherapy type
Long-course radiotherapy	18 (90.0)
Short-course radiotherapy	2 (10.0)
Neoadjuvant chemotherapy regimen
CAPOX	14 (70.0)
Capecitabine	3 (15.0)
FOLFOX	3 (15.0)
cCR	15 (75.0)
pCR	5 (25.0)
Local recurrence during follow-up among complete responders	(n = 20)
Yes	2 (10.0)
No	18 (90.0)

Data were showed as mean ± SD, median (interquartile range), or n (%). Both local recurrence events occurred exclusively in the complete clinical response watch-and-wait subgroup (2/15; 13.3%). ECOG: Eastern Cooperative Oncology Group; CEA: Carcinoembryonic antigen; cCR: Complete clinical response; pCR: Pathological complete response.

Table 3 Exploratory univariate analysis of factors associated with complete clinical response after neoadjuvant treatment (n = 101)

Variable	Measure of association (OR)	95%CI	P value
Categorical variables (univariate logistic regression)
Sex (male vs female)	1.19	0.35-4.05	0.77
Hemoglobin (< 10 g/dL vs ≥ 10 g/dL)	1.14	0.30-4.32	0.97
CEA (> 5 ng/mL vs ≤ 5 ng/mL)	0.98	0.76-1.17	0.83
Albumin (≤ 3 g/dL vs > 3 g/dL)	0.59	0.20-1.75	0.67
Tumor size (per cm increase)	0.77	0.61-0.96	0.028
Tumor location (lower rectum vs others)	0.98	0.20-4.33	0.89
Clinical stage (III vs II)	1.32	0.59-2.97	0.49
Neoadjuvant treatment (CRT vs RT alone)	0.70	0.12-4.04	0.86
Continuous variables (Student’s t test)
Age at diagnosis (years)	0.0111	-20.6 to 20.8	0.991
Distance from anal verge (cm)	1.6551	-4.8 to 5.3	0.215
Degree of luminal stenosis (%)	0.8201	-31.4 to 249.7	0.382

¹t statistic.

All analyses are exploratory and based on univariate models. Given the limited number of complete clinical response events (n = 15), multivariable modeling was not performed to avoid overfitting. Therefore, results should not be interpreted as demonstrating independent predictive effects. CEA: Carcinoembryonic antigen; CRT: Chemoradiotherapy; RT: Radiotherapy.