Cancer survivors’ lean body mass found to be lower than the general population, which was connected with prior abdominal or pelvic radiation.
Adult survivors of childhood abdominal and pelvic cancers who were treated with radiation therapy experience body composition abnormalities and worse cardiometabolic health compared with the general population, according to a recent study published in Cancer Epidemiology, Biomarkers & Prevention.
Previous reports had been made regarding the impact of radiation therapy on the metabolic health of survivors of pediatric leukemia, brain tumors, and hematopoietic stem cell transplants. However, the radiation therapy’s effect on survivors of pediatric abdominal and pelvic tumors had not yet been assessed.
"Body composition abnormalities and cardiometabolic impairments are of concern among survivors given that in the general population, these conditions increase the risk of developing life-threatening diseases including cardiovascular disease and type 2 diabetes," said Carmen Wilson, PhD, assistant member in the Epidemiology and Cancer Control Department at St. Jude Children's Research Hospital, in a press release.
Specifically, the analyses showed that survivors of abdominal and pelvic solid tumors had low lean body mass, which is the measurement of the non-fat content of the body. The researchers found that survivors’ lean body mass was lower than the general population and that the lower relative lean body mass was connected with the prior abdominal or pelvic radiation. Those individuals with lower lean body mass burn fewer calories while resting than those with higher lean body mass, Wilson explained.
In conducting the study, the researchers assessed 431 adult survivors of pediatric abdominal or pelvic solid tumors who were treated at St. Jude Children's Research Hospital. At the time of the study, the median age of the participants was 29.9 years.
Of the childhood diagnoses, the most frequent were neuroblastoma, Wilms tumor, and germ cell tumor, with a median age of 3.6 years at diagnosis. Approximately 37% of participants had received abdominal radiation therapy and 36% had received pelvic radiation therapy during their treatment.
In order to assess the participants' body composition, metabolic abnormalities, and physical function in relation to the general population, the researchers used data from the 2013 to 2014 National Health and Nutrition Examination Survey (NHANES) that matched the age, sex, and ethnicity of the patients in the study.
The researchers found that compared with individuals from NHANES, the survivors of abdominal and pelvic solid tumors had a significantly higher likelihood of having insulin resistance (33.8% vs. 40.6%), high triglycerides (10.02% vs. 18.4%), and low levels of high-density lipoproteins (28.9% vs. 33.5%), which are commonly referred to as good cholesterol. However, the levels of low-density lipoproteins (bad cholesterol) between survivors and individuals from NHANES showed no significant differences.
"It is possible that abdominal and pelvic-directed radiation therapy damages postural muscles or subtly impairs sex hormone production, ultimately affecting muscle mass," Wilson said in the press release.
Radiation therapy has been previously shown to cause muscle injury, resulting in the loss of muscle fiber and muscle regenerative cells in animal studies, Wilson explained. She noted that lifestyle choices could potentially affect relative lean mass and cardiometabolic health as well.
The researchers said that it would be beneficial for future research on the topic to examine the effect of radiation therapy and other cancer treatments in relation to fat distribution in the body. This is of particular interest because increased abdominal obesity can be a stronger predictor of adverse effects than overall obesity, according to the study.
Additionally, Wilson noted that she is interested in investigating how lifestyle behaviors might influence lean mass among survivors of pediatric cancers.
"While it may not be possible to avoid radiation therapy as a key treatment for many solid tumors, early research suggests that resistance training interventions in survivors increase lean mass," Wilson said. "Further work is needed to see if training would also impact cardiometabolic impairments in this population."
Radiation to treat pediatric cancers may have lasting impact on heart and metabolic health. American Association for Cancer Research; August 13, 2020. eurekalert.org/pub_releases/2020-08/aafc-rtt081020.php. Accessed August 14, 2020.