International validation and update of the Amsterdam model for prediction of survival after pancreatoduodenectomy for pancreatic cancer
BACKGROUND:
The objective of this study was to validate and update the Amsterdam prediction model including tumor grade, lymph node ratio, margin status and adjuvant therapy, for prediction of overall survival (OS) after pancreatoduodenectomy for pancreatic cancer.

METHODS:
We included consecutive patients who underwent pancreatoduodenectomy for pancreatic cancer between 2000 and 2017 at 11 tertiary centers in 8 countries (USA, UK, Germany, Italy, Sweden, the Netherlands, Korea, Australia). Model performance for prediction of OS was evaluated by calibration statistics and Uno's C-statistic for discrimination. Validation followed the TRIPOD statement.

RESULTS:
Overall, 3081 patients (53% male, median age 66 years) were included with a median OS of 24 months, of whom 38% had N2 disease and 77% received adjuvant chemotherapy. Predictions of 3-year OS were fairly similar to observed OS with a calibration slope of 0.72. Statistical updating of the model resulted in an increase of the C-statistic from 0.63 to 0.65 (95% CI 0.64-0.65), ranging from 0.62 to 0.67 across different countries. The area under the curve for the prediction of 3-year OS was 0.71 after updating. Median OS was 36, 25 and 15 months for the low, intermediate and high risk group, respectively (P < 0.001).

CONCLUSIONS:
This large international study validated and updated the Amsterdam model for survival prediction after pancreatoduodenectomy for pancreatic cancer. The model incorporates readily available variables with a fairly accurate model performance and robustness across different countries, while novel markers may be added in the future. The risk groups and web-based calculator www.pancreascalculator.com may facilitate use in daily practice and future trials.
Research authors: van Roessel, S, Strijker, M, Steyerberg, EW, ..., Besselink, MG
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Discrimination

Rows included 0
C-index 0.69 ROC
Brier score 0
Scaled Brier score 0

Classification plot

Not specified

Calibration

Regression coefficient 0.72
Intercept 0.07
Hosmer-Lemeshow GOF < 0.001
 

Calibration plot

Histogram

Not specified

Decision curve

Not specified
Comparison
Original study population: 350
Validation study population: 3081

Categorical characteristics

Name Subset / Group Nr. of patients Validation P-Value
American Society of Anesthesiologists (ASA) grade ASA I 75 Not available
ASA II 211
ASA III/IV 64
Jaundice Yes 288 Not available
No 62
Preoperative drainage Yes 224 Not available
No 126
Resection procedure Whipple 48 1774 Not available
PPPD 302 1304
Adjuvant therapy Yes 123 2359 Not available
No 227 722
Overall morbidity Yes 184 Not available
No 166
Surgical morbidity Yes 143 Not available
No 207
In-hospital mortality Yes 4 Not available
No 346
Resection margin R0 141 1785 Not available
R1 198 1296
R2 11 0
TNM classification T1 35 657 Not available
T2 84 1934
T3 223 410
T4 6 63
Tx 2 0
N0 98 663
N1 252 2418
M0 342 3081
M1 8 0
Perineural growth Yes 107 2671 Not available
No 243 410
Angioinvasion Yes 60 Not available
No 290
Tumor differentiation Grade I (well) 28 192 Not available
Grade II (moderate) 199 1848
Grade III (poor) 123 1041

Continuous characteristics

Name Mean SD Unit Plot
Original Validation Age 64
66
10
years
Original Validation Body mass index (BMI) 24
6
kg/m2
Original Validation Tumor size 2.8
3.0
1.5
cm
Name LL Q1 Median Q3 UL Unit
Original Validation Number of lymph nodes
5
8
13

nodes
Original Validation Hospital stay
10
14
19

days
Original Validation Lymph node ratio (positive lymph nodes/total number of lymph nodes)
0
0.2
0.4

ratio
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