NEW YORK-Clinicians should base cancer therapy decisions not on a patient's chronological age, but rather his or her "biologic age," according to Irwin H. Krakoff, MD. Better criteria than simply "date of birth" should be used for both study and treatment of cancer in the elderly, said Dr. Krakoff, adjunct professor of medicine at New York University Cancer Institute, New York, NY. Biologic Differences "We need to realize that the elderly...are not just people with gray hair, wrinkles, and a different date on their drivers license," Dr. Krakoff emphasized. "There are biologic differences. Tumor types are different in the elderly compared with younger people, and their tolerances to therapy and their cure rates are different." Pediatric oncology experience provides a precedent for this perspective. Recently, Dr. Krakoff noted, investigators have recognized that children are "not merely small people" but are biologically different from adults and therefore have different tumor-type incidences, therapy tolerance, and cure rates-despite the fact that a tumor manifesting in a child may be morphologically similar to the same tumor in an adult. Likewise, in the elderly, there arebiologic differences vs younger adults, leading to an increased incidence of certain tumors, decreased tolerance to aggressive therapy, and appearance of tumors that do not occur in younger patients. Although it is tempting to use mere age as a landmark in defining "elderly," one should bear in mind that many individuals considered elderly simply because they are 65 years of age or older are still quite "biologically youthful," said Dr. Krakoff. Conversely, headded, many patients who are not near the age at which they could collect Social Security benefits are "old beyond their years" in terms of health status. Treatment of cancers that occur commonly in the biologically elderly, such as lung, pancreatic, or colorectal cancer, is still a difficult enterprise, Dr. Krakoff said, in contrast to the marked advances in treating cancers that primarily affect younger patients, such as acute lymphoblastic leukemia, gestational trophoblastic tumors, and testicular cancer. "Although we havehad some minor successes, serious problems remain," he added. Treatment Validation Studies Needed The dilemma is that cancer must be studied in older patients if it is to be effectively treated. In practice, Dr. Krakoff noted, older patients receive treatment that has been validated in younger groups, but unfortunately, the elderly are often specifically excluded from clinical trials per protocol. Likewise, outside of the experimental setting, elderly patients are frequently undertreated as well. To gain a better understanding of how the elderly might be treated, it is important to investigate the molecular biology of cancer-specific aberrations in specific tumors in elderly populations. "The elderly have a greater proclivity to develop cancer, probably due to biology we still don't fully understand," Dr. Krakoff said. "I am very optimistic that the current emphasis and current explorations in molecular biology and genetics are going to give us further answers...I hope that we will be able to cope not just with cancer in young or middle aged, but in the elderly as well."