Brain cancer, once thought to reach a peak rate in patients in their 60s and then decline rapidly, now appears to continue to increase dramatically in older Americans to age 85 and beyond, says a new study in today's issue of the Journal of the National Institute of Cancer.
"The rate of brain cancer appears to have increased up to five-fold -- or up to 400 percent -- for elderly groups in 1985 compared to the rates measured from 1973 and 1974 and we find this alarming," says Dr. Nigel H. Greig, a neuroscientist and researcher with the National Institute on Aging.
Instead of peaking in patients between the ages of 65 and 69, "the peak brain cancer rate now shows up 10 years later in patients 75 to 79 years of age," he says.
The study further shows that among those aged 75 to 79, the brain cancer rate in 1985 was twice that in 1973-74; among those aged 80 to 84, the increase was fourfold, and among those 85 and older, there was a fivefold increase.
"We feel that at least part of this detected increase is a true increase," says Greig, who attributes the escalation of brain cancer cases in the elderly to a number of different factors.
Sophisticated diagnostic tools -- such as the CT (computerized tomography) scanner and MRI, magnetic resonance imaging, which allows doctors to see brain cancer even more clearly -- have played a major role in the 1970s and 1980s in uncovering a large number of brain cancer cases, he says.
And, a greater interest in the health of the elderly since the mid-1970s, particularly due to Alzheimer's disease, has pushed doctors to be more precise in their evaluation of illness in the elderly, he says.
Further studies are now under way, Greig says, to determine the extent of the "true increase" in brain cancer incidence among the elderly.
Dr. Richard S. Kaplan, head of neuro-oncology at the University of Maryland Cancer Center, says, "I'm surprised to hear someone speculate about an up to 400 percent increase in brain cancer among the elderly.
"This should not be a cause for panic and apprehension. This probably represents, more than anything else, our capacity to make a brain cancer diagnosis using the CT scanner and MRI, rather than a steady increase in true disease."
The new and continuing work is a collaborative effort that includes Dr. Stanley I. Rapaport, the co-author who heads the neuroscience laboratory at NIA in Bethesda, and collaborators Lynn G. Ries and Rosemary Yancik of the National Cancer Institute, also in Bethesda.
While the incidence rates shot up among the elderly over the 12-year period examined, the study showed virtually no change in incidence rates in all other age groups.
"The findings are alarming because there is no quick fix for this disease," Greig says. "This is just about a universally fatal disease and the treatment is not particularly good right now.
"And, it's alarming because with the treatment that there is, half of the patients are dead within 10 months. If you're elderly, you're on the lower end of that. If you're younger, you're on the upper end."
The study focused on primary brain cancer -- those tumors that start in the brain, not tumors that spread to the brain from other parts of the body. The most common brain tumors in the elderly were gliomas or glioblastoma multiform, and astrocytoma -- both aggressive, dangerous forms of cancer.
Brain cancer is relatively rare in the population as a whole. Each year, there are about 15,000 brain cancer patients in all age groups. Knowledge of risk factors is "very limited" and environmental factors to which everybody is exposed may have a role, Greig says.
Brain cancer is a difficult disease to treat because its cell population is very dissimilar, Greig says. Some cells will be insensitive and other cells will develop resistant mechanisms.
"The worst problem is the cancer's location in the brain," he says. "Both surgeons and radiologists have to be extremely careful not to damage the normal surrounding tissue. Once brain cells are killed, they will not regenerate."
More and better treatment drugs are needed, Greig says, because a single new drug will not have much impact on this killer disease.