Nonmetastatic breast cancer patients with low muscle mass face higher mortality

According to research published April 5 in the Journal of the American Medical Association, nonmetastatic breast cancer patients with sarcopenia, or low muscle mass, may have a higher mortality rate than those without.  

"The importance of body size on cancer outcomes is of great clinical interest," wrote lead author Bette Caan, DrPH, a senior research scientist and a nutritional epidemiologist at the Kaiser Permanente Northern California Division of Research in Oakland, California. "Measures of body composition that can distinguish adipose tissue distribution, as well as the quantity and quality of muscle, can help refine our understanding of body size to cancer survival."  

The team analyzed CT scans taken between January 2000 to December 2013 of 3,241 female. Patients were between the ages of 18 and 80 and diagnosed with stage II or III invasive breast cancer (who also underwent abdominal or pelvic CT scan at the time of diagnosis). Muscle area, muscle radiodensity and adiposity were measured from CT scans within six months of diagnosis and before chemotherapy or radiation, the researchers wrote.  

Of the total number of patients, 34 percent had sarcopenia and 37 percent had low muscle radiodensity, the researchers wrote. Additionally, those with sarcopenia showed a higher mortality rate than those without.  

However, body mass index (BMI) alone was found to be unrelated to mortality, the researchers noted. Measures of sarcopenia and adiposity may also provide prognostic information that BMI cannot. The authors explained their study demonstrated the effects of muscle consistently across age, BMI and cancer stage.  

"We demonstrated that sarcopenia is not a condition restricted to patients with later-stage disease but rather is highly prevalent among patients with nonmetastatic disease across all levels of BMI," the researchers wrote. "Our findings are likely generalizable across many other nonmetastatic cancers because the associations with muscle and improved survival for those with metastatic cancer has been observed across a variety of solid tumors."