Muscle-Wasting in Cancer Shown to Affect Heart

Disease reduces heart function, changes organ's muscle structure

(RxWiki News) New research suggests that muscle wasting associated with certain cancers causes significant damage to the heart. Before the study, cachexia (characterized by muscle wasting, dramatic weight loss, fatigue, weakness and loss of appetite) was thought to spare the organ.

In mice with colon cancer, cachexia was shown to reduce heart function. The syndrome also changed the mice’s heart muscle structure, according to a recent Ohio State University study.

Previous studies have suggested cachexia to be responsible for up to one-third of all cancer deaths, though means to predict who is most susceptible to the illness remain elusive. Many aspects of the syndrome remain misunderstood.

Martha Belury, lead author of the research and a professor of human nutrition at Ohio State, said knowing which types of cancer are associated with the wasting disease is vital in regard to treatment options. Colon cancer along with other gastrointestinal tumors and certain lung cancers are most associated with cachexia.

“It might be important to think about heart function earlier rather than once people are starting to lose weight,” Belury said. “Clinicians could try to protect the heart while also giving patients chemotherapy for cancer and perhaps added nutrition to maintain weight.”

Researchers compared mice with and without colon cancer, and by day 14, when the mice with tumors had lost weight, scientists measured cardiac function using ultrasound. The mice with tumors had a heart rate of almost 21 percent fewer beats per minute. The afflicted mice’s hearts also pumped significantly less blood than the hearts of the healthy mice.

By day 17 cachexia had taken hold in the mice with cancer, marked by a 23 percent difference in body weight in the healthy and sick mice. Researchers then examined the mice’s hearts with electron microscopy and found clear signs of damage, including an increase in fibrous tissue and changes in the cells that convert carbon to energy (mitochondria).

“The mitochondria looked pretty bad, almost as if they were breaking apart,” Belury said. “And we also saw evidence of the precursors of scarring, or collagen formation, which you don’t want to see in any type of muscle and especially not in the heart muscle.”

Dr HQ Han, from California-based US biotech company Amgen Research, recently demonstrated that muscle plays a key role in cancer survival. The study suggests that reversing muscle wastage associated with cachexia could improve survival rates.

Researchers found that mice in which muscle wasting had been prevented (by using a drug to block a protein secreted by tumors) lived significantly longer, even as their tumors continued to grow.

Heart-muscle wastage was also reversed in the mice in which the protein-pathway had been blocked.

Reviewed by: 
Review Date: 
September 14, 2010