Rheumatoid arthritis patients at higher risk of cancer death

People with rheumatoid arthritis are at an increased risk of dying from cancer but are not more likely to develop it, according to a study published in the March Arthritis & Rheumatism.

Researchers analyzed data on 2,105 patients in primary care practices in Norfolk County, England, who were diagnosed with inflammatory polyarthritis between 1990 and 1999. Investigators concluded that most with this diagnosis progressed to rheumatoid arthritis, and these patients had a 40% increased risk of dying of cancer within five years compared with the general population. In this population, a 60% increased risk of developing hematopoietic cancer was detected -- a finding evidenced in previous studies. But the risk of developing other cancers was not amplified.

"Patients with RA who develop cancer have a reduced survival which may be due to several factors," said Dr. Alan Silman, senior author and professor of rheumatic disease epidemiology at the University of Manchester, also in England.

This study is the latest attempt to explain why RA patients have double the risk of death from a wide array of medical conditions. "The data underscore one of the important contributors to morbidity and mortality associated with rheumatoid arthritis," said Jack Cush, MD, chief of rheumatology and clinical immunology at Presbyterian Hospital in Dallas. He was not affiliated with this project.

Experts suggest that this may be caused by delays in cancer diagnosis, because the pain caused by a carcinoma can be mistaken for that associated with rheumatoid arthritis. In light of this study and others, specialists suggest that patients' new symptoms may be caused by some other disease process such as cancer, although screening above and beyond what is recommended for the general population is unnecessary.

"We have a high vigilance for cancer with rheumatoid arthritis patients. We do routine screening that is age and gender appropriate, and we're directed by symptoms," said Eric L. Matteson, MD, MPH, a rheumatologist and professor of medicine at Mayo Clinic in Rochester, Minn. "But we don't scan everybody, every year. That's not worth it."

The additional cancer mortality also may be a result of the inflammatory process caused by RA or the drugs used to treat it. The labels of anti-tumor necrosis factor antibody therapies that treat this condition warn of an increased risk of cancer, although studies have been mixed. One in the May 17, 2006, Journal of the American Medical Association found an increased risk. Another presented at the American College of Rheumatology meeting in November 2006 did not. Experts consider the risk to be small, if it exists, and these drugs are generally regarded as safe.

"It's still an open question. It's hard to separate the effect of the disease from the treatment," said Dr. Matteson, one of the authors of the JAMA study. "In the end, I think it's likely that rheumatoid arthritis increases the risk of cancer."

These patients also could be saddled with infections and cardiovascular disease. And having two diseases, no matter what they are, is probably far worse than one.

"My sense is that it's the overall burden of illness," said Fred Wolfe, MD, lead author on the ACR study and director of the National Data Bank for Rheumatic Diseases in Wichita, Kan. "Patients with diabetes and pneumonia are probably worse than those who have pneumonia and not diabetes."

Previous studies also found higher rates of lung and skin cancer, but lower rates of colorectal and digestive tract cancers, in these patients.