ESTRO 2024 - Abstract Book

S1975

Clinical - Mixed sites, palliation

ESTRO 2024

probability estimate (CPE) statistics. Time-dependent areas under the receiver operating characteristic curves (AUC) were used to assess the capability of DMV groups as a prognostic marker for OS over time.

A p-value threshold of 0.05 was designated for statistical significance.

Results:

A total of 221 and 349 patients were included from the PVC and RVC, respectively, compared to 303 in the RDC. The median age was 69 years in the PVC, 68 years in the RVC and 66 years in the RDC. The most common primary tumors were prostate (24.0%) and colorectal cancer (18.6%) in the PVC, non-small cell lung cancer (23.2%) and colorectal cancer (21.5%) in the RVC, compared to lung (36.3%) and non-colorectal gastrointestinal cancers (14.5%) in the RDC. The median time from SBRT to distant failure was 7.7 months (range 0.32-49.5) in the PVC, 8.5 months (range 0.7 67.15) in the RVC, compared to 3.6 (range 0.03-42.9) in the RDC. The median number of lesions at distant failure was 3 (range 1-32) in the PVC, 1 (range 1-7) in the RVC, compared to 3 (range 1-100) in the RDC. These resulted in a median DMV of 0.37 (range 0.02-32.0) in the PVC, 0.17 (range 0.01-15.22) in the RVC, compared to 0.71 (range 0.02 121.8) in the RDC.

DMV groups differed significantly in OS in both the PVC (p=0.0006) and the RVC (p<0.0001) (Fig. 1), as was the case in the RDC (p<0.0001).

DMV groups also differed significantly in WFFS (calculated for the subgroup of patients with 5 or fewer metastases at first distant failure) in the PVC (p=0.016, n=166) and in the RVC (p< 0.0001, n=341) (Fig. 2), comparable to the RDC (p=0.037, n=215).

Gönen & Heller’s CPE for the single variable Cox proportional hazard model for OS including the three DMV groups was 0.59 (SE 0.02) in the PVC, 0.56 (SE 0.01) in the RVC, compared with 0.61 (SE 0.02) in the RDC.

Mean time-dependent AUC for OS, which assesses the discrimination over time, was 0.66 (95% CI 0.68-0.72) for the PVC, 0.63 (95% CI 0.62-0.64) in the RVC, compared with 0.65 (95% CI 0.65-0.67) in the RDC.