Table S1.Association among baseline characteristics and PET-CT parameters (SUVmax, WB SUVmax, and WB TLG) in all patients (n=124).

Variables
N / SUVmax (primary tumor) / WB SUVmax / WB TLG
Simple linear / Multiple / Simple linear / Multiple / Simple linear / Multiple
median (range) / β / P-value / β / P-value / median (range) / β / P-value / β / P-value / median (range) / β / P-value / β / P-value
Sex
Male / 80 / 7.15 (1.9-34.6) / 0.033 / 0.715 / 8.6 (1.9-34.6) / -0.030 / 0.745 / 427.95 (0-13609.8) / 0.109 / 0.229
Female / 44 / 5.95 (1.0-30.8) / 7.95 (1.6-39.1) / 391.9 (0-4428.0)
Age, year
≥65 / 23 / 7.8 (1.0-28.4) / 0.016 / 0.864 / 8.6 (1.8-28.4) / -0.026 / 0.776 / 420.7 (0-8463.5) / 0.103 / 0.255
<65 / 101 / 6.3 (1.6-34.6) / 8.5 (1.6-39.1) / 426.0 (0-13609.8)
Differentiation
WD/MD / 40 / 8.05 (1.0-34.6) / 0.158 / 0.080 / 0.076 / 0.416 / 11.05 (3.7-34.6) / 0.187 / 0.038 / 0.160 / 0.125 / 724.05 (56.4-13609.8) / 0.186 / 0.039 / 0.150 / 0.132
PD/SRC/others / 84 / 5.7 (1.6-30.8) / 7.35 (1.6-39.1) / 312.35 (0-9290.7)
Baseline CEA ng/ml
≥5 / 54 / 7.15 (1.0-34.6) / 0.111 / 0.219 / 9.1 (1.9-39.1) / 0.106 / 0.241 / 635.3 (0-13609.8) / 0.190 / 0.035
<5 / 70 / 6.25 (1.6-28.4) / 7.85 (1.6-28.4) / 302.4 (0-9290.7)
Baseline CA19-9, ng/ml
≥37 / 45 / 7.3 (2.4-34.6) / 0.013 / 0.885 / 9.0 (3.4-34.6) / 0.017 / 0.848 / 598.9 (9.3-13609.8) / 0.126 / 0.163
<37 / 79 / 6.0 (1.0-28.4) / 7.8 (1.6-39.1) / 305.5 (0-7673.9)
Baseline CA72-4, ng/ml (n=98)
≥8 / 46 / 7.5 (2.4-30.8) / 0.151 / 0.138 / 9.9 (3.4-30.8) / 0.227 / 0.024 / 0.204 / 0.037 / 689.05 (18.1-8463.5) / 0.211 / 0.037 / 0.237 / 0.018
<8 / 52 / 5.95 (1.0-34.6) / 7.35 (1.8-34.6) / 257.8 (0-13609.8)
Primary tumor location
Distal / 55 / 6.5 (1.0-28.4) / 0.071 / 0.430 / 7.6 (2.7-39.1) / -0.003 / 0.978 / 343.8 (1.7-7673.9) / -0.045 / 0.623
Proximal / 69 / 7.0 (1.6-34.6) / 8.6 (1.6-34.6) / 581.4 (0-13609.8)
HER2 status
Positive / 34 / 9.05 (3.0-34.6) / 0.261 / 0.003 / 0.234 / 0.014 / 11.95 (3.4-34.6) / 0.314 / <0.001 / 0.248 / 0.019 / 603.4 (92.7-13609.8) / 0.122 / 0.177
Negative / 90 / 5.85 (1.0-28.4) / 7.35 (1.6-39.1) / 331.5 (0-9290.7)
Hepatic metastasis
Present / 29 / 7.9 (1.0-17.1) / 0.026 / 0.773 / 9.9 (3.7-22.2) / 0.064 / 0.484 / 1348.4 (27.4-13609.8) / 0.347 / <0.001 / 0.304 / 0.003
Absent / 95 / 6.3 (1.6-34.6) / 7.6 (1.6-39.1) / 319.2 (0-7072.5)
Peritoneal metastasis
Present / 69 / 6.0 (1.6-30.8) / -0.139 / 0.124 / 7.6 (1.6-30.8) / -0.101 / 0.265 / 384.1 (0-7072.5) / -0.159 / 0.078
Absent / 55 / 7.5 (1.0-34.6) / 9.1 (2.7-39.1) / 556.6 (1.9-13609.8)

Abbreviations: MD, adenocarcinoma, moderately differentiated; MTV, metabolic tumor volume; PD, adenocarcinoma, poorly differentiated; SRC, signet-ring cell carcinoma; SUVmax, maximum standardized uptake value; TLG, total lesion glycolysis; WB, whole body; WD, adenocarcinoma, well differentiated.

Table S2. Simple linear Cox analyses ofPFS and OS according to clinicopathological features and PET-CT parameters in HER2-negative gastric cancer patients (n =90).

PFS / OS
Simple linear / Simple linear
Variable / N / Median, month / HR (95% CI) / P-value / -2 loglikelihood ratio / Median, month / HR (95% CI) / P-value / -2 loglikelihood ratio
Sex
Male / 56 / 5.7 / 0.910 (0.586-1.413) / 0.674 / 10.8 / 1.151 (0.737-1.797) / 0.538
Female / 34 / 5.3 / 1 / 12.8 / 1
Age at diagnosis, year
≥65 / 16 / 6.7 / 0.910 (0.523-1.575) / 0.736 / 11.1 / 1.378 (0.780-2.434) / 0.270
<65 / 74 / 5.2 / 1 / 11.6 / 1
Differentiation
PD/SRC/others / 70 / 5.6 / 1.161 (0.692-1.948) / 0.571 / 10.8 / 1.197 (0.709-2.022) / 0.501
WD/MD / 20 / 5.1 / 1 / 11.6
Baseline CEA, ng/ml
≥5 / 32 / 5.8 / 0.747 (0.476-1.171) / 0.203 / 12.5 / 0.743 (0.471-1.172) / 0.202
<5 / 58 / 5.2 / 1 / 10.5 / 1
Baseline CA19-9, ng/ml
≥37 / 26 / 3.1 / 1.104 (0.687-1.777) / 0.682 / 9.9 / 1.298 (0.807-2.087) / 0.282
<37 / 64 / 5.7 / 1 / 12.3 / 1
Baseline CA72-4, ng/ml (n=73)
≥8 / 31 / 4.8 / 1.284 (0.791-2.085) / 0.312 / 9.1 / 1.442 (0.889-2.341) / 0.138
<8 / 42 / 5.3 / 1 / 12.5 / 1
Primary tumor location
Distal / 38 / 6.5 / 0.812 (0.526-1.253) / 0.346 / 14.7 / 0.881 (0.568-1.366) / 0.571
Proximal / 52 / 4.5 / 1 / 10.5 / 1
Hepatic metastasis
Present / 18 / 5.3 / 1.211 (0.784-1.873) / 0.388 / 11.6 / 0.975 (0.563-1.688) / 0.927
Absent / 72 / 5.5 / 1 / 11.1 / 1
Peritoneal metastasis
Present / 53 / 5.1 / 0.809 (0.437-1.381) / 0.437 / 10.2 / 1.353 (0.869-2.106) / 0.181
Absent / 37 / 6.5 / 1 / 12.5 / 1
SUVmax (primary tumor)
>10 / 14 / 4.4 / 1.371 (0.769-2.444) / 0.284 / 7.4 / 1.936 (1.079-3.476) / 0.027 / 607.329
≤10 / 76 / 5.7 / 1 / 12.3 / 1
WB SUVmax
>10 / 24 / 3.9 / 1.682 (1.040-2.722) / 0.034 / 612.843 / 8.5 / 1.678 (1.038-2.713) / 0.035 / 607.451
≤10 / 66 / 5.8 / 1 / 12.5 / 1
WB SUVmean
>4 / 20 / 4.4 / 1.558 (0.934-2.599) / 0.089 / 10.2 / 1.444 (0.870-2.399) / 0.156
≤4 / 70 / 5.7 / 1 / 12.5 / 1
WB MTV (cm3)
>100 / 52 / 4.1 / 1.864 (1.201-2.892) / 0.005 / 609.103 / 9.0 / 1.932 (1.233-3.028) / 0.004 / 603.005
≤100 / 38 / 6.8 / 1 / 14.7 / 1
WB TLG
>600 / 36 / 4.2 / 1.642 (1.061-2.542) / 0.026 / 612.214 / 8.2 / 1.751 (1.130-2.713) / 0.012 / 605.524
≤600 / 54 / 5.7 / 1 / 13.7 / 1

Abbreviations: CA19-9, carbohydrate antigen 19-9; CA72-4, carbohydrate antigen 72-4; CEA, carcinoembryonic antigen; CI, confidence interval; GEJ, gastroesophageal junction; HER2, human epidermal growth factor 2; HR, hazard ratio; MD, adenocarcinoma, moderately differentiated; MTV, metabolic tumor volume; PD, adenocarcinoma, poorly differentiated; PET, positron emission tomography; SRC, signet-ring cell carcinoma; SUVmax, maximum standardized uptake value; SUVmean, mean standardized uptake value; TLG, total lesion glycolysis; WD, adenocarcinoma, well differentiated; WB, whole body.

Table S3.Simple linear and multiple Cox analyses ofPFS and OS according to clinicopathological features and PET-CT parameters in HER2-positive gastric cancer patients with trastuzumab as first-line treatment (n =34).

PFS / OS
Simple linear / Multiple / Simple linear / Multiple* / Multiple†
Variable / N / Median,
month / HR (95% CI) / P-value / HR (95% CI) / P-value / Median,
month / HR (95% CI) / P-value / HR (95% CI) / P-value / HR (95% CI) / P-value
Sex
Male / 24 / 5.8 / 1.210 (0.564-2.598) / 0.625 / 14.9 / 0.642 (0.294-1.403) / 0.266
Female / 10 / 6.8 / 1 / 14.1 / 1
Age at diagnosis, year
≥65 / 7 / 14.1 / 0.529 (0.213-1.315) / 0.171 / 14.9 / 0.727 (0.290-1.818) / 0.495
<65 / 27 / 5.9 / 1 / 14.7 / 1
Differentiation
PD/SRC/others / 14 / 5.8 / 1.327 (0.627-2.809) / 0.456 / 13.8 / 2.572 (1.139-5.808) / 0.023 / 1.669 (0.732-3.806) / 0.223 / 1.588 (0.689-3.660) / 0.278
WD/MD / 20 / 6.8 / 1 / 16.8 / 1 / 1 / 1
Baseline CEA, ng/ml
≥5 / 22 / 5.5 / 2.443 (1.082-5.516) / 0.032 / 3.300 (1.046-7.747) / 0.006 / 12.2 / 2.107 (0.937-4.735) / 0.071 / 2.274 (0.946-5.467) / 0.067 / 1.874 (0.767-4.579) / 0.168
<5 / 12 / 7.4 / 1 / 1 / 16.8 / 1 / 1 / 1
Baseline CA19-9, ng/ml
≥37 / 19 / 6.8 / 1.119 (0.528-2.367) / 0.770 / 15.7 / 0.959 (0.449-2.049) / 0.959
<37 / 15 / 5.8 / 1 / 14.1 / 1
Baseline CA72-4, ng/ml (n=25)
≥8 / 15 / 7.4 / 0.572 (0.242-1.355) / 0.205 / 19.2 / 0.591 (0.248-1.407) / 0.591
<8 / 10 / 5.5 / 1 / 14.2 / 1
Primary tumor location
Distal / 17 / 6.6 / 1.263 (0.622-2.566) / 0.519 / 14.2 / 0.871 (0.417-1.819) / 0.713
Proximal / 17 / 6.8 / 1 / 15.6 / 1
HER2 positivity
IHC2+/amplification by ISH / 7 / 5.0 / 1.864 (1.159-2.995) / 0.010 / 2.354 (1.388-3.993) / 0.001 / 13.2 / 3.000 (1.164-7.731) / 0.023 / 5.222 (1.716-15.887) / 0.004 / 4.514 (1.529-13.330) / 0.006
IHC3+ / 27 / 7.9 / 1 / 1 / 16.8 / 1 / 1 / 1
Hepatic metastasis
Present / 11 / 6.6 / 0.800 (0.366-1.750) / 0.576 / 19.2 / 1.069 (0.483-2.363) / 0.870
Absent / 23 / 5.9 / 1 / 14.7 / 1
Peritoneal metastasis
Present / 16 / 5.8 / 1.133 (0.557-2.308) / 0.730 / 12.2 / 1.729 (0.830-3.603) / 0.144
Absent / 18 / 6.8 / 1 / 15.7 / 1
SUVmax (primary tumor)
>10 / 13 / 6.8 / 0.568 (0.248-1.301) / 0.181 / 15.6 / 0.607 (0.274-1.345) / 0.218
≤10 / 21 / 6.6 / 1 / 14.1 / 1
WB SUVmax
>10 / 22 / 5.8 / 0.989 (0.469-2.087) / 0.977 / 14.1 / 1.011 (0.479-2.138) / 0.976
≤10 / 12 / 6.6 / 1 / 19.2 / 1
WB SUVmean
>4 / 19 / 5.8 / 1.035 (0.503-2.130) / 0.926 / 14.7 / 0.837 (0.394-1.780) / 0.644
≤4 / 15 / 7.4 / 1 / 16.8 / 1
WB MTV(cc)
>100 / 19 / 6.6 / 1.315 (0.630-2.744) / 0.466 / 14.1 / 2.263 (1.069-5.211) / 0.034 / 2.887 (1.216-6.855) / 0.016
≤100 / 15 / 5.9 / 1 / 15.6 / 1 / 1
WB TLG
>600 / 17 / 5.8 / 1.753 (0.831-3.696) / 0.140 / 13.8 / 2.836 (1.269-6.335) / 0.011 / 2.703 (1.127-6.478) / 0.026
≤600 / 17 / 7.4 / 1 / 16.8 / 1 / 1

Abbreviations: CA19-9, carbohydrate antigen 19-9; CA72-4, carbohydrate antigen 72-4; CEA, carcinoembryonic antigen; CI, confidence interval; GEJ, gastroesophageal junction; HER2, human epidermal growth factor 2; HR, hazard ratio; IHC, immunohistochemical staining; ISH, in situ hybridization; MD, adenocarcinoma, moderately differentiated; MTV, metabolic tumor volume; PD, adenocarcinoma, poorly differentiated; PET, positron emission tomography; SRC, signet-ring cell carcinoma; SUVmax, maximum standardized uptake value; SUVmean, mean standardized uptake value; TLG, total lesion glycolysis; WD, adenocarcinoma, well differentiated; WB, whole body.

*Cox regression model calculated using pathological differentiation, baseline serum CEA, HER2 IHC/ISH status, and WB MTV, excluding WB TLG. The -2-log likelihood ratio of this model is 145.0.

†Cox regression model calculated using pathological differentiation, baseline serum CEA, HER2 IHC/ISH status, and WB TLG, excluding WB MTV. The -2-log likelihood ratio of this model is 146.1.

FIGURE LEGENDS

Figure S1. Consort flow diagram of this study

FigureS2. Survival outcomes according to tumor HER2 status in all patients (n=124).

(A) PFS according to HER2 status; (B) OS according to HER2 status.

Figure S3. Survival outcomes according to SUVmax, WB SUVmean, and WB MTV in all patients (n = 124).

(A) PFS according to SUVmax; (B) OS according to SUVmax;
(C) PFS according to WB SUVmean; (D) OS according to WB SUVmean;
(E) PFS according to WB MTV; (F) OS according to WB MTV.

Abbreviations: MTV, metabolic tumor volume; OS, overall survival;PFS, progression free survival; SUVmax, maximum standardized uptake value; SUVmean, mean standardized uptake value; WB, whole body.

Figure S4. PFS according to WB SUVmax and WB TLG in HER2-negative gastric cancer group (n=90) and HER2-positive gastric cancer group (n = 34).

(A) PFS according to WB SUVmax in HER2-negative gastric cancer group;

(B) PFS according to WB SUVmax in HER2-positive gastric cancer group;

(C) PFS according to WB TLG in HER2-negative gastric cancer group;

(D) PFS according to WB TLG in HER2-positive gastric cancer group;

Abbreviations: HER2, human epidermal growth factor receptor 2; OS, overall survival; PFS, progression free survival; SUVmax, maximum standardized uptake value; TLG, total lesion glycolysis; WB, whole body.