Muscle size and muscle fat infiltration in patients with newly diagnosed prostate cancer: a case-control study

Cancer is a recognized risk factor for sarcopenia. While some studies suggest that androgen deprivation therapy (ADT) may contribute to muscle loss in patients with prostate cancer (PCa), it remains unclear whether alterations in muscle composition are already present at the initial diagnosis, before any treatment begins. This study aimed to evaluate computed tomography (CT)-based muscle size and muscle fat infiltration in patients with newly diagnosed prostate cancer.

A total of 143 patients with newly diagnosed PCa (January 2023-June 2024) were enrolled and matched 1:2 with 286 controls. CT attenuation and cross-sectional area of the erector spinae (ES) and full-layer muscle at the T12 level were measured. The muscle-to-spleen attenuation ratio (M/S) was calculated. Muscle fat infiltration was assessed based on muscle CT attenuation. Multivariable logistic regression analyses were performed to examine the association between PCa and the risk of low muscle CT attenuation or low muscle area.

In PCa patients, muscle CT attenuation, M/S ratio, ES area, and full-layer muscle area decreased with advancing age. Overall, muscle CT attenuation and M/S ratio were significantly lower in the PCa group than in controls. Both ES area and full-layer muscle area were also significantly reduced in PCa patients younger than 70years. A similar difference in ES area was observed in the 70-80-year age group. After full adjustment, PCa was significantly associated with an increased risk of low ES CT attenuation (OR=2.59, 95%CI: 1.25-5.39), low full-layer muscle CT attenuation (OR=7.14, 95%CI: 3.30-15.45), low full-layer muscle M/S ratio (OR=4.29, 95%CI: 2.01-8.87), and low ES area (OR=2.94, 95%CI: 1.33-6.53). Similar associations were observed in the non-diabetic subgroup.

Newly diagnosed prostate cancer is associated with an increased risk of CT-based skeletal muscle fat infiltration and reduced muscle area.