Survival after resection of perihilar cholangiocarcinoma-development and external validation of a prognostic nomogram

Abstract

Background: The objective of this study was to derive and validate a prognostic nomogram to predict disease-specific survival (DSS) after a curative intent resection of perihilar cholangiocarcinoma (PHC).

Patients and methods: A nomogram was developed from 173 patients treated at Memorial Sloan Kettering Cancer Center (MSKCC), New York, USA. The nomogram was externally validated in 133 patients treated at the Academic Medical Center (AMC), Amsterdam, The Netherlands. Prognostic accuracy was assessed with concordance estimates and calibration, and compared with the American Joint Committee on Cancer (AJCC) staging system. The nomogram will be available as web-based calculator at mskcc.org/nomograms.

Results: For all 306 patients, the median overall survival (OS) was 40 months and the median DSS 41 months. Median follow-up for patients alive at last follow-up was 48 months. Lymph node involvement, resection margin status, and tumor differentiation were independent prognostic factors in the derivation cohort (MSKCC). A nomogram with these prognostic factors had a concordance index of 0.73 compared with 0.66 for the AJCC staging system. In the validation cohort (AMC), the concordance index was 0.72, compared with 0.60 for the AJCC staging system. Calibration was good in the derivation cohort; in the validation cohort patients had a better median DSS than predicted by the model.

Conclusions: The proposed nomogram to predict DSS after curative intent resection of PHC had a better prognostic accuracy than the AJCC staging system. Calibration was suboptimal because DSS differed between the two institutions. The nomogram can inform patients and physicians, guide shared decision making for adjuvant therapy, and stratify patients in future randomized, controlled trials.

Keywords: cholangiocarcinoma; nomogram; prognostic model; survival.

Figure 1.

Nomogram. The predicted 3- and 5-year DSS can be read from this nomogram in two steps: (i) Draw a vertical line for each prognostic factor (margin, nodes, differentiation) from its appropriate value (e.g. for margin the values are ‘wide’, ‘narrow’, and ‘positive’) to the axis termed ‘points’ at the top of the figure. The points assigned for the value of each prognostic factor can be read where the vertical line crosses the ‘points’ axis. (ii) Add the three point scores determined at step 1 and find the sum score on the axis termed ‘total points’. Determine the predicted 3- and 5-year DSS by drawing a vertical line from the sum score on the axis termed ‘total points’ down to the 3- and 5-year DSS axes. The predicted 3-year DSS can be read where the vertical line crosses with the axis termed ‘3-year DSS’.