June 2, 2003 -- Fibromyalgia patients and other people with unexplained body pain may be at increased risk for cancer. A study from the U.K. shows that people with body pain who had never been diagnosed with cancer subsequently had a higher incidence of cancer and reduced cancer survival, compared with people without widespread pain.
The investigation is the first to link body pain to a higher risk of developing cancer, and its authors caution that the findings are far from conclusive.
"These data have to be replicated in other studies, and until we do that I think we have to remain somewhat skeptical," study author Gary J. Macfarlane, MD, tells WebMD. "This may well be a chance finding, but it is important that we look into it further."
Widespread chronic body pain for which no cause can be found is the major feature of fibromyalgia, a condition that affects an estimated 3.7 million people -- mostly women -- in the U.S. In earlier research, Macfarlane and colleagues from England's University of Manchester investigated whether having widespread body pain affects life span. In his previous study, he demonstrated an increased death rate in people reporting widespread body pain. The increase in death rate was almost all related to cancer deaths.
"We didn't do this study because we believed these people had an increased risk of cancer," he says. "That was a complete surprise."
In this follow-up study, the researchers attempted to determine whether their earlier findings represented a real increase in cancer risk among patients with fibromyalgia-like pain, or whether the observation suggested delayed cancer diagnosis in these patients.
Roughly 6,000 subjects from the earlier study participated in the follow-up. A total of 15% had reported having widespread body pain, while 48% reported regional body pain and 37% reported no pain. None had been diagnosed with cancer when enrolled in 1991, but 395 developed the disease over the next nine years.
Cancer incidence was lowest among people who had reported having no pain in the original survey and was highest for those who reported widespread body pain. Breast, prostate, and colorectal cancers were diagnosed most frequently.
Among cancer patients in all groups, those who had reported widespread pain were almost twice as likely to die from the disease as those reporting no pain. The findings are published in the June issue of the journal Arthritis and Rheumatism.
"There are a number of possible explanations [for the observed link], but they are just theories at the moment," Macfarlane says.
But fibromyalgia expert Lawrence J. Leventhal, MD, says there is nothing in the previous literature to suggest that patients with fibromyalgia are at increased risk for early cancer death, or early death from other causes.
"Certainly other conditions I deal with, like rheumatoid arthritis and lupus, have been linked to a shortened life span, but this is not true of fibromyalgia," the Philadelphia rheumatologist says. "I would be very surprised if there turns out to be any increase in death from cancer or a shortened life span for any reason associated with fibromyalgia."