Metastatic castration‑resistant prostate cancer (mCRPC) increasingly requires treatment decisions that account for patient physiological reserve. This retrospective analysis of 213 mCRPC patients treated with first‑line androgen receptor pathway inhibitors (ARPIs) — abiraterone or enzalutamide — sought to determine whether probable sarcopenia (low muscle mass) predicted overall survival (OS), toxicity, and quality of life (QoL) when geriatric and inflammatory markers were taken into account.
The investigators aimed to compare the prognostic value of low muscle mass against established geriatric screening and comorbidity instruments, and to explore whether combining clinical and laboratory markers could identify patients at very high risk of treatment‑related severe toxicity.
The cohort included 213 men with mCRPC who received first‑line ARPIs. Probable sarcopenia was operationalized using skeletal muscle index (SMI) with a cutoff of < 40.8 cm²/m². Other baseline assessments included the G8 geriatric screening tool and the Cumulative Illness Rating Scale for Geriatrics (CIRS‑G) to quantify comorbidity burden. Inflammatory markers such as neutrophil‑to‑lymphocyte ratio (NLR) and serum albumin were also evaluated.
Geriatric vulnerability was assessed using the G8 screening instrument; comorbidity burden was measured with CIRS‑G. Inflammatory status incorporated routine laboratory markers including NLR and albumin. These measures were incorporated into survival models and used in a classification and regression tree (CART) analysis to identify combined clinical phenotypes associated with high toxicity risk.
Primary endpoints were overall survival (OS) and incidence of grade ≥ 3 toxicity. Secondary outcomes included biochemical response at three months (PSA50) and trajectory of quality of life deterioration.
Among the 213 patients, 93 (reported as having probable sarcopenia by SMI) had substantially shorter median OS compared with patients without low muscle mass: 12.7 versus 24.7 months (p < 0.001). Univariable Cox analysis showed increased mortality risk associated with probable sarcopenia (HR = 2.17, p < 0.001).
Despite the survival difference, early biochemical tumor response did not differ between groups: three‑month PSA50 rates were essentially identical (86.0% vs 85.8%, p = 1.000), indicating comparable initial response to ARPI therapy irrespective of muscle mass status.
When geriatric and inflammatory variables were included in multivariable models, the independent effect of low muscle mass on mortality was attenuated and not statistically significant (adjusted HR = 1.05, p = 0.783). Instead, measures of physiological vulnerability and chronic disease burden remained independent predictors of death: higher CIRS‑G scores (HR = 1.21, p < 0.001) and worse G8 scores reflecting frailty (G8: HR = 0.85, p < 0.001) were associated with mortality in adjusted analyses. These findings suggest that the adverse survival signal observed with probable sarcopenia in univariable testing may be mediated by coexisting frailty and comorbid conditions.
A CART analysis combining comorbidity and inflammatory markers identified a phenotype at very high risk for severe treatment‑related toxicity. The high‑risk node was defined by CIRS‑G > 8.5, NLR > 3.35, and albumin ≤ 3.35 g/dL; patients with this combination experienced an extremely high rate of grade ≥ 3 toxicity (reported as 98%). This composite phenotype highlights how integrating routine clinical scores and laboratory markers can flag patients who may require intensified monitoring or alternative treatment strategies.
Probable sarcopenia was associated with more rapid deterioration in quality of life (QoL) over time. The abstract reports a statistically significant association between low muscle mass and faster QoL decline, emphasizing a functional and patient‑centered consequence of sarcopenia beyond survival statistics.
In this cohort of mCRPC patients treated with first‑line ARPIs, mortality initially linked to low muscle mass in univariable analysis was largely explained by underlying frailty and comorbidity when comprehensive geriatric and inflammatory assessments were included. The study supports the value of routine geriatric screening (G8), comorbidity quantification (CIRS‑G), and simple inflammatory markers (NLR, albumin) to refine prognostic stratification and to anticipate severe toxicity. Use of combined clinical and laboratory metrics may help clinicians identify patients who need tailored supportive care or modified treatment plans.
The abstract reports that external validation is warranted. Details such as imaging modalities for SMI measurement, timing of geriatric assessments, full model covariates, and specifics of toxicity grading beyond the aggregated grade ≥ 3 endpoint are not provided in the abstract and therefore were not available for this summary. The study design was retrospective, which may introduce selection and information biases; these limitations and other methodological details should be reviewed in the full text.
Overall, these results advocate integrating geriatric and inflammatory evaluations into routine assessment of older patients with mCRPC receiving ARPIs to improve prognostication and toxicity risk prediction.