Patients with metastatic renal cell carcinoma (mRCC) treated with targeted therapies have a better prognosis if they also have a high quality of muscle, study findings indicate.
The results showed that these patients survived twice as long – without disease progression – as patients with low-quality muscle.
Also, skeletal muscle density, as a measure of muscle quality, when integrated with Heng risk score improved prognosis prediction, which in turn could enhance management of mRCC.
“Prognostic factors for improved OS [overall survival] are lacking for patients with mRCC because the prognosis has been improved with targeted therapies,” note author Sami Antoun (Institut Gustave-Roussy, Villejuif, France) and colleagues.
“By integrating the SMD [skeletal muscle density] status in the Heng risk score, we were able to add a new prognostic group among the patients with intermediate-risk and favorable-risk Heng scores,” they report in Cancer.
The average OS ranged from 8 months for patients with an intermediate-risk Heng score and low SMD to 22 months for those with an intermediate-risk Heng score and high SMD or favorable-risk Heng score and low SMD, and 35 months for those with a favorable-risk Heng score and high SMD.
SMD was assessed in 149 mRCC patients receiving targeted therapy (primarily vascular endothelial growth factor inhibitor therapy) using computed tomography imaging of the skeletal muscle to measure its mean radiation attenuation, expressed in Hounsfield units (HU).
The median OS was 21.4 months and the median muscle density was 38 HU in men and 36 HU in women. The two factors were strongly associated, with OS being twice as long in those with high versus low SMD, at an average of 29 months and 14 months, respectively.
The pattern was the same for progression-free survival, with corresponding averages of 8 versus 4 months in patients with high versus low SMD.
After adjusting for Heng risk score and treatment, SMD below the median was associated with a 1.9-fold increased risk for death and a twofold increased risk for disease progression.
OS and progression-free survival were not associated with body mass index, adipose tissue, or, contrary to the researchers’ expectations, with skeletal muscle area.
“The results of the current study indicate that muscle density could be used as a prognostic factor and could improve the usual prognostic scores,” the team concludes.
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