Prognostic value of preoperative enhanced computed tomography as a quantitative imaging biomarker in pancreatic cancer

Table 1 Patient characteristics, n (%)

Patient characteristics	n = 67
Age (yr)
≤ 60	31 (46.3)
> 60	36 (53.7)
Sex
Male	42 (62.7)
Female	25 (37.3)
Tumour location
Head/uncinate	44 (65.7)
Body/tail	23 (34.3)
CA19-9
< 37 ng/mL	20 (29.9)
≥ 37 ng/mL	47 (70.1)
AJCC stage (2017)
I	11 (16.4)
II	27 (40.3)
III	29 (43.3)
Tumour differentiation
Highly/moderately	49 (73.1)
Poorly/undifferentiated	18 (26.9)
Surgical margin
Negative	57 (85.1)
Positive	10 (14.9)
Vascular invasion
No	51 (76.1)
Yes	16 (23.9)
Adjuvant chemotherapy
No	33 (49.3)
Yes	34 (50.7)

CA19-9: Carbohydrate antigen 19-9; AJCC: American Joint Committee on Cancer.

Table 2 Computed tomography attenuation values and tumour relative enhancement ratio

Location, phase and TRER	Value
ROT
Nonenhancement phase (HU)	36.1 (31.0-39.2)
PV phase (HU)	58.0 (50.3-70.0)
PTOT
Nonenhancement phase (HU)	43.5 (36.8-48.1)
PV phase (HU)	82.7 (71.8-98.4)
TRER	0.57 (0.41-0.78)

TRER: Tumour relative enhancement ratio; ROT: Region of the overall tumour; PTOT: Pancreatic tissue outside the tumour; PP: Pancreatic parenchymal; PV: Portal venous.

Table 3 Computed tomography enhancement situation comparing the portal venous phase to the pancreatic parenchymal phase

CT enhancement situation (PV phase and PP phase)	No. of patients (n)
	PV phase > PP phase	PV phase < PP phase
ROT	64	3
PTOT	50	17

ROT: Region of the overall tumour; PTOT: Pancreatic tissue outside the tumour; PP: Pancreatic parenchymal; PV: Portal venous.

Table 4 Baseline characteristics of the low-and high-enhancement groups

Variable	TRER ≤ 0.7, No. of patients, n (%)	TRER > 0.7, No. of patients, n (%)	P value
Age (yr)			0.397
≤ 60	22 (50.0)	9 (39.1)
> 60	22 (50.0)	14 (60.9)
Sex			0.170
Male	25 (56.8)	17 (73.9)
Female	19 (43.2)	6 (26.1)
Tumour location			0.117
Head/uncinate	26 (59.1)	18 (78.3)
Body/tail	18 (40.9)	5 (21.7)
CA19-9			0.230
< 37 ng/mL	11 (25.0)	9 (39.1)
≥ 37 ng/mL	33 (75.0)	14 (60.9)
AJCC stage (2017)			0.015
I	4 (9.1)	7 (30.4)
II	16 (36.4)	11 (47.8)
III	24 (54.5)	5 (21.7)
Tumour differentiation			0.634
Highly/moderately	33 (75.0)	16 (69.6)
Poorly/undifferentiated	11 (25.0)	7 (30.4)
Vascular invasion			0.071
No	30 (68.2)	21 (91.3)
Yes	14 (31.8)	2 (8.7)
Surgical margin			0.501
Negative	36 (81.8)	21 (91.3)
Positive	8 (18.2)	2 (8.7)
Adjuvant chemotherapy			0.087
No	25 (56.8)	8 (34.8)
Yes	19 (43.2)	15 (65.2)

CA19-9: Carbohydrate antigen 19-9; AJCC: American Joint Committee on Cancer; TRER: Tumour relative enhancement ratio.

Table 5 Univariate analysis using Cox regression for postoperative overall survival in all patients

Variable	No. of patients, n (%)	No. of events	Median OS (mo) (95%CI)	P value
Age (yr)				0.699
≤ 60	31 (46.3)	27	14.6 (9.1-20.0)
> 60	36 (53.7)	30	10.2 (5.7-14.7)
Sex				0.651
Male	42 (62.7)	34	10.2 (4.3-16.1)
Female	25 (37.3)	23	13.6 (9.2-18.1)
Tumour location				0.836
Head/uncinate	44 (65.7)	36	12.0 (7.7-16.3)
Body/tail	23 (34.3)	21	12.8 (4.1-21.6)
AJCC stage (2017)				0.005
I	11 (16.4)	6	27.3 (14.9-39.6)
II	27 (40.3)	23	12.0 (10.2-13.8)
III	29 (43.3)	28	8.9 (5.0-12.7)
CA19-9				0.033
< 37 ng/mL	20 (29.9)	14	15.8 (10.4-21.2)
≥ 37 ng/mL	47 (70.1)	43	11.3 (7.2-15.3)
Tumour differentiation				0.255
Highly/moderately	49 (73.1)	42	14.7 (11.9-17.6)
Poorly/undifferentiated	18 (26.9)	15	8.2 (5.7-10.7)
Surgical margin				0.141
Negative	57 (85.1)	47	12.3 (7.5-17.1)
Positive	10 (14.9)	10	12.0 (2.9-21.1)
Vascular invasion				0.435
No	51 (76.1)	41	12.3 (7.7-16.9)
Yes	16 (23.9)	16	12.0 (4.8-19.2)
Adjuvant chemotherapy				0.000
No	33 (49.3)	32	8.2 (6.6-9.7)
Yes	34 (50.7)	25	17.7 (14.4-20.9)
TRER				0.001
≤ 0.7	44 (65.7)	42	10.0 (5.9-14.1)
> 0.7	23 (34.3)	15	22.0 (12.4-31.6)

CI: Confidence interval; CA19-9: Carbohydrate antigen 19-9; AJCC: American Joint Committee on Cancer; TRER: Tumour relative enhancement ratio; OS: Overall survival.

Table 6 Multivariate analysis using Cox regression for postoperative overall survival in all patients

Variable	Hazard ratio	95%CI	P value
CA19-9 (ng/mL)	2.279	1.174-4.422	0.015
Tumour differentiation	3.057	1.585-5.898	0.001
Surgical margin	2.860	1.315-6.222	0.008
Adjuvant chemotherapy	0.200	0.106-0.380	0.000
TRER	0.432	0.229-0.812	0.009

CI: Confidence interval; CA19-9: Carbohydrate antigen 19-9; TRER: Tumour relative enhancement ratio.

Table 7 Correlation between tumour relative enhancement ratio and clinicopathological characteristics

Variable	TRER ≤ 0.7, No. of patients, n (%)	TRER > 0.7, No. of patients, n (%)	P value	Coefficient of correlation
Tumour location			0.117	0.192
Head/uncinate	26 (59.1)	18 (78.3)
Body/tail	18 (40.9)	5 (21.7)
CA19-9			0.230	0.147
< 37 ng/mL	11 (25.0)	9 (39.1)
≥ 37 ng/mL	33 (75.0)	14 (60.9)
AJCC stage (2017)1			0.003	-0.353
I	4 (9.1)	7 (30.4)
II	16 (36.4)	11 (47.8)
III	24 (54.5)	5 (21.7)
T stage			0.005	0.343
T1/2	13 (29.5)	15 (65.2)
T3/4	31 (70.5)	8 (34.8)
N stage1			0.046	-0.245
N0	12 (27.3)	11 (47.8)
N1	15 (34.1)	8 (34.8)
N2	17 (38.6)	4 (17.4)
Lymph node metastasis			0.138	0.181
Negative	13 (29.5)	11 (47.8)
Positive	31 (70.5)	12 (52.2)
Vascular invasion			0.071	0.258
No	30 (68.2)	21 (91.3)
Yes	14 (31.8)	2 (8.7)
Tumour differentiation			0.634	0.058
Highly/moderately	33 (75.0)	16 (69.6)
Poorly/undifferentiated	11 (25.0)	7 (30.4)

¹Spearman rank correlation was used, and Spearman correlation coefficient was calculated. The other variables were tested by chi-square test, and Cramer’s V correlation coefficient was calculated.

CA19-9: Carbohydrate antigen 19-9; AJCC: American Joint Committee on Cancer; TRER: Tumour relative enhancement ratio.