FaceAge in Patients with Oligometastatic Cancer: External Validation and Racial Differences in Facial Age Estimates

Purpose: FaceAge is a deep learning biomarker that estimates biological age from facial photographs and has been associated with survival in patients with metastatic cancer. We hypothesized that FaceAge would predict survival in patients with oligometastases and that the newer foundation model FaceAge 2.0 would have smaller racial differences compared to FaceAge 1.0. Methods & Materials: Between 2014 and 2023, 177 consecutive patients with 1 to 5 distant metastases were treated with comprehensive involved-site radiation at a community hospital. Frontal facial photographs obtained during radiation simulation were processed with FaceAge 1.0 and FaceAge 2.0/FAHR-Face. Photographs from 167 patients met quality criteria. Associations with overall survival (OS) were evaluated using Kaplan-Meier estimates, Cox regression and the concordance index. We compared FaceAge estimates across racial groups after adjusting for chronological age. Results: At a median follow-up of 44.0 months, the median OS was 42.8 months. After adjusting for chronological age, FaceAge 1.0 scores were underestimated in Black patients, with a mean difference of 10.6 years (p<0.001) compared to White patients. When using FaceAge 2.0, the difference decreased to 3.0 years (p=0.16). On univariable analysis, FaceAge 1.0 (HR 1.03 per year, p=0.004) and FaceAge 2.0 (HR 1.03 per year, p=0.002) both predicted OS, consistent with previous FaceAge studies. Chronological age was also strongly prognostic (HR 1.04 per year, p<0.001) and remained significant on multivariable analysis. Adding FaceAge to chronological age and established prognostic factors only modestly improved discrimination (C-index 0.74 without FaceAge vs. 0.75 with FaceAge 1.0 or 2.0). Conclusions: FaceAge was externally validated as a univariable prognostic biomarker in oligometastatic cancer. FaceAge 2.0 substantially reduced racial disparities in facial age estimates seen with FaceAge 1.0. Further studies are warranted to determine whether facial aging models perform consistently across racial groups before routine clinical use.