Conditional Probability of Long-term Survival After Liver Resection for Intrahepatic Cholangiocarcinoma A Multi-institutional Analysis of 535 Patients

IMPORTANCE Whereas conventional actuarial overall survival (OS) estimates rely exclusively on static factors determined around the time of surgery, conditional survival (CS) estimates take into account the years that a patient has already survived. OBJECTIVE To define the CS of patients following liver resection for intrahepatic cholangiocarcinoma (ICC). DESIGN, SETTING, AND PARTICIPANTS Between January 1, 1990, and December 31, 2013, a total of 535 patients who underwent resection of ICC were identified from an international multi-institutional database. In this retrospective international study conducted from January to June 2014, clinicopathological characteristics, operative details, and long-term survival data were analyzed. Conditional survival estimates were calculated as the probability of survival for an additional 3 years. INTERVENTION Resection of ICC. MAIN OUTCOMES AND MEASURES Overall survival and CS. RESULTS While actuarial OS decreased over time from 39% at 3 years to 16% at 8 years (P = .002), the 3-year CS (CS3) increased over time among those patients who survived. The CS3 at 5 years-the probability of surviving to postoperative year 8 after having already survived to postoperative year 5-was 65% compared with 8-year OS of 16%(P = .002). Factors that were associated with worse OS included larger tumor size (hazard ratio [HR], 1.02; 95% CI, 1.00-1.05; P = .05), multifocal disease (HR, 1.49; 95% CI, 1.19-1.86; P = .01), lymph node metastasis (HR, 2.21; 95% CI, 1.67-2.93; P < .01), and vascular invasion (HR, 1.39; 95% CI, 1.10-1.75; P = .006). The calculated CS3 exceeded the actuarial survival for all high-risk subgroups. For example, patients with lymph node metastasis had an actuarial OS of 11% at 6 years vs a CS3 of 49% at 3 years (Delta 38%). Similarly, patients with vascular invasion had an actuarial OS of 15% at 6 years compared with a CS3 of 50% at 3 years (Delta 35%). CONCLUSIONS AND RELEVANCE Conditional survival estimates may provide critical quantitative information about the changing probability of survival over time among patients undergoing liver resection for ICC. Therefore, such estimates can be of significant value to patients and health care professionals.