Conditional disease-free survival after curative-intent liver resection for neuroendocrine liver metastasis

Background: Neuroendocrine liver metastases (NELM) are typically associated with high recurrence rates following surgical resection. Conditional disease-free survival (CDFS) estimates may be more clinically relevant compared to actuarial survival estimates. Methods: CDFS was assessed using a multi-institutional cohort of patients. Cox proportional hazards models were used to evaluate factors associated with disease-free survival (DFS). Three-year CDFS (CDFS3) estimates at “x” year after surgery were calculated as CDFS₃ = DFS(x + 3)/DFS(x). Results: A total of 521 patients met the inclusion criteria. While actuarial 3-year DFS gradually decreased from 49% at 1 year to 39% at 5 years, CDFS₃ increased over time. CDFS₃ at 5 years was estimated as 89% vs actuarial 8-year DFS of 39% (P <.001). The probability of remaining disease-free at 5 years after resection increased as patients remained disease-free. For example, the probability of being disease-free for an additional 3 years was 66.3% and 88.8% for patients who lived 2 and 5 years, respectively. Overall, CDFS₃ in each subgroup increased postoperatively as years elapsed, however, the impact of each prognostic factor on CDFS₃ changed over time. Conclusion: CDFS of patients who underwent resection of NELM exponentially improved as patients survived additional years without recurrence. CDFS provides more accurate prognostic measures compared with traditional DFS measures.