Validation of a postresection pancreatic adenocarcinoma nomogram for disease-specific survival

Abstract

Purpose: Nomograms are statistically based tools that provide the overall probability of a specific outcome. They have shown better individual discrimination than the current TNM staging system in numerous patient tumor models. The pancreatic nomogram combines individual clinicopathologic and operative data to predict disease-specific survival at 1, 2, and 3 years from initial resection. A single US institution database was used to test the validity of the pancreatic adenocarcinoma nomogram established at Memorial Sloan-Kettering Cancer Center.

Patients and methods: The nomogram was created from a prospective pancreatic adenocarcinoma database that included 555 consecutive patients between October 1983 and April 2000. The nomogram was validated by an external patient cohort from a retrospective pancreatic adenocarcinoma database at Massachusetts General Hospital that included 424 consecutive patients between January 1985 and December 2003.

Results: Of the 424 patients, 375 had all variables documented. At last follow-up, 99 patients were alive, with a median follow-up time of 27 months (range, 2 to 151 months). The 1-, 2-, and 3-year disease-specific survival rates were 68% (95% CI, 63% to 72%), 39% (95% CI, 34% to 44%), and 27% (95% CI, 23% to 32%), respectively. The nomogram concordance index was 0.62 compared with 0.59 with the American Joint Committee on Cancer (AJCC) stage (P = .004). This suggests that the nomogram discriminates disease-specific survival better than the AJCC staging system.

Conclusion: The pancreatic cancer nomogram provides more accurate survival predictions than the AJCC staging system when applied to an external patient cohort. The nomogram may aid in more accurately counseling patients and in better stratifying patients for clinical trials and molecular tumor analysis.

Fig 1

Instructions: Locate patient’s variable on the corresponding axis. Draw a line to the Points axis. Sum the points. Draw a line from the Total Points axis to the 12-, 24-, 36-Month DSS axis to determine the patient’s probability of dying from adenocarcinoma within 3 years, assuming the patient does not die of another cause first. DSS, disease-specific survival; M, male; F, female; Y, yes; N, no.

Fig 2

Kaplan-Meier survival curves for the Massachusetts General Hospital cohort of 375 patients based on (A) nomogram groupings and (B) American Joint Committee on Cancer stage.

Fig 3

Calibration of the Memorial Sloan-Kettering Cancer Center (MSKCC) nomogram with the Massachusetts General Hospital (MGH) data set. Nomogram applied to the MGH data set (n = 375) at (A) 1 year, (B) 2 years, and (C) 3 years. The diagonal line represents the performance of an ideal nomogram. The line containing error bars (95% CI) represents the performance of the MSKCC nomogram applied to the MGH data set.

Fig 4

Comparisons of nomogram predictions with the predictions of the American Joint Committee on Cancer (AJCC) stage groupings. Note the heterogeneity of predicted survival probabilities within each AJCC stage.