Abstract Introduction Molecular tumor boards (MTBs) integrate clinical, pathological, and molecular data to prioritize therapy options. Because MTB-guided treatment starts at varying time points after MTB discussion, vulnerabities to immortal time bias occur if treatment delay is ignored. Methods Retrospective survival analysis of 949 consecutive individuals discussed at the University Cancer Center Hamburg MTB (2016-2022). Index date (t0) was the first MTB discussion. Therapy initiation was modeled as a time-dependent exposure using Mantel-Byar methods and visualized with Simon-Makuch plots. Therapy strata were priority 1 targeted, priority 2 targeted, and non-targeted therapy. Results Among solid tumors (n = 854), targeted therapy was implemented in 24% and was off-label in 51%. ORR/DCR were 30.8%/61% for priority 1, 11.4%/36.4% for priority 2, and 37.5%/52.1% for non-targeted therapy (p = 0.017). The progression-free survival ratio (MTB-directed therapy vs immediately preceding line) exceeded 1.3 in 63% of targeted therapy recipients. From the MTB date, median survivalMTB was 16.5 months (priority 1), 15.5 months (priority 2), and 11.0 months (non-targeted). In Mantel-Byar analysis, progression-free survivalSimonMakuch favored priority 1 (p = 0.002) with 1-year rates of 28%, 12%, and 15% for priority 1, priority 2, and non-targeted therapy, respectively. One-year overall survivalSimonMakuch was 52%, 34%, and 42%. In a time-dependent Cox model, priority 1 was associated with lower risk of death versus no targeted post-MTB therapy (hazard ratio 0.80, 95% confidence interval 0.64-0.99, p = 0.038). Conclusions After correction for immortal time bias, implementation of the top-priority MTB recommendation was associated with improved disease control and survival signals, although confounding and selection effects remain key limitations.
Velthaus-Rusik et al. (Tue,) studied this question.