Cancer is primarily a disease of the elderly. Yet participation by the elderly in clinical trials is not nearly proportional to their representation in the population with cancer.
According to a Southwest Oncology Group study published Dec. 30 in the New England Journal of Medicine, 63% of all cancer patients are older than 65, but they only make up 25% of those enrolled in studies. The numbers get worse for breast cancer: The elderly make up 49% of breast cancer patients, but only 9% of patients 65 or older are in clinical trials for the disease.
Several years ago, federal rules mandated that clinical trials be made up of both women and minorities in proportion to the percentage of the population that has the disease. And in fact, the SWOG study found that these goals have been met.
But those same federal guidelines said nothing of the elderly.
"We need to determine the best cancer therapies for elderly patients as well as for younger patients, which may not be the same," said Lawrence N. Shulman, M.D., vice chair for clinical services in the Department of Adult Oncology at Dana-Farber Cancer Institute in Boston. "The biology of cancers is sometimes different in elderly patients, and the toxicity profile of the treatments we use may be different for elderly patients as well."
While few researchers were surprised by the findings, the question remains, why do so few elderly participate in cancer trials?
In some cases, the problem starts with physicians.
A previously published survey of U.S. oncologists found that while 80% thought that patients had better results when treated in clinical trials, roughly half said they would not recommend patients for clinical trials based on age alone.
One reason may be the belief that those cancer patients 65 and up cannot stand up to the rigors of potentially toxic drugs.
"Theres a tendency among oncologists to say, Theyre older, why bother them, " said Lee Rosen, M.D., director of the Cancer Therapy Development Program at the University of California at Los Angeles Jonsson Comprehensive Cancer Center. "Theres no question that some drugs can help the elderly. If we had studies that randomly assigned patients to low dose versus supportive care, and show the benefit to quality of life, that might support a lot more people to be more aggressive," he said.
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But excluding the elderly misses the point of a trial in the first placeto find out how well a particular drug will work in all patients, including the 65-and-older set, said Maurie Markman, M.D., chairman of the Taussig Cancer Center at the Cleveland Clinic. "We need to make sure that were including all the conditions in the real world for patients," he said.
"If youre not capturing this patient population in trials, its a problem in terms of generalization of results, knowledge, and understanding of how to deal with these situations. I think its important that the elderly are included in trials to make sure you have enough experience with dealing with side effects and find out if you have to give certain dose modifications," he said. "Because most research is done on younger patients, treatments may not be appropriate or may be ineffective in the group most likely to develop cancer."
To some degree, the under-representation of the elderly owes to the realities and business of conducting cancer clinical trials, said John Wasson, M.D.
"You can follow younger individuals for a longer time, and the drug manufacturer is able to recoup money because those patients will live longer," said Wasson, who is the director of the Center for Aging at Dartmouth Medical School in Hanover, N.H.
"That doesnt work when you have an 85-year-old with many different conditions and limited life expectancy," he said. "Its hard to do a study on a group of such individuals because results are difficult to interprettheres so much data noise." As a result, oncologists "need more of them because competing hazardsother diseaseswill take so many out of the study, and you likely cant follow them for long."
Elderly Dont Enroll
In some cases, it is the patients who are reluctant players. While younger patients may be more aggressive in seeking out trials and treatments, older patients may be more likely to wait to be asked. Aminah Jatoi, M.D., assistant professor of oncology at Mayo Clinic Cancer Center, Rochester, Minn., believes a major reason the elderly dont enroll in trials is because they are not asked to.
"If you ask an oncologist how a certain patient will do in chemotherapy, most oncologists would predict a particularly elderly patient would not do well," she said.
"How many elderly want to embark on trial with the potential for significant toxicity?" asked Samuel Taylor, M.D., medical director of the Creticos Cancer Center at the Illinois Masonic Medical Center in Chicago. Many older adults decide they are not willing to undergo potentially grueling treatments to extend their lives.
"Quality becomes more important," said Georgia Sadler, Ph.D., associate director of the University of California at San Diego Cancer Center and director of community outreach. Some elderly patients simply cannot or will not keep up with the study regimen and are more likely to drop out than are younger patients. Still others have trouble getting to a medical center to see the doctor.
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Social and family support also play a tremendously important role in a seniors participation, Trimble said. The elderly tend to become more isolated as they age. Family and friends help influence treatment decisions and are more likely to encourage younger patients to enroll in trials.
Specialized Trials
While the researchers who conducted the SWOG study and others have called for greater participation of the elderly in clinical trials, some, such as UCSDs Sadler, advocate specialized trials for the elderly.
Whereas younger patients seek the most aggressive treatments, such trials would employ milder treatments for people who probably will not live much more than 10 to 20 years.
"We have to have standard clinical trials to know whether a drug works or not," Sadler said. "But we need additional studies because we need to know what happens when we introduce this new drug in someone taking a number of other medications for other health problems. These types of trials will become more important as we age as a society."
"The question is, is it better to give a woman a full dose of chemotherapy for her cancer although she has diminished kidney function, or is it better to give a lower dose, which overall provides a better quality of life?"
Some existing trials focus exclusively on the elderly, though they are by far the exception. The North Central Cancer Treatment Group is conducting a multi-institutional 40-patient phase II trial of carboplatin and taxol for non-small-cell lung cancer for patients 65 and older. Because of potential toxicity, researchers have made dose modifications.
Other groups have begun similar studies. The Cancer and Leukemia Group B is conducting a randomized study of women over 65 comparing intravenous and oral chemotherapy for stage II breast cancer.
Getting the elderly to take part in trials will continue to be increasingly important, researchers agree. "Cancer in the elderly has not been carefully studied," said Richard Schilsky, M.D., chairman of CALGB and associate dean for clinical research at the University of Chicago. "When it has, its not clear its different in the elderly than in younger people."
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