Cancer is a global term given to a collection of diseases (n >100), all of which are characterized by cells which undergo abnormal, uncontrolled growth. In the case of solid tumors, this expansion in cell numbers creates large masses or tumors, which can either remain in place (benign) or release cells that can then migrate or metastasize to distant tissues, reestablishing the primary tumor. Currently, cancer is viewed as being a genetic disease arising from either inborn or inherited genetic defects or genetic defects caused by cumulative exposure to environmental or carcinogenic factors. Surgery is the primary method for treating most isolated solid cancers and may play a role in palliation and prolongation of survival. This intervention has the goal of removing cancerous masses and surrounding tissues and lymphatic structures, which may harbor cancerous cells and permit their movement to other parts of the body. Another treatment intervention is radiation therapy, which uses high-energy particles to destroy cancer cells and thus eliminate or shrink tumors. The effects of radiation therapy are localized; however, normal cells in the radiation field can also be damaged or destroyed. Finally, chemotherapy involves the treatment of cancer with drugs. Older chemotherapeutic drugs, while effective, typically lack specificity for the cancer cells resulting in widespread damage to healthy cells and tissues. Recently developed drugs have been designed to target specific molecules that are either involved in regulating cancer cell growth or are unique to the cancer cells, earning these drugs the designation of "targeted" therapies. Typically, chemotherapy drugs are given in combination with other chemotherapeutic drugs in an effort to successfully treat the cancer. Many cancer survivors are treated with more than 1 of these 3 primary interventional therapies (surgery, radiation, and chemotherapy), and it is quite clear that these therapies whether used either in isolation or in combination with other therapies can adversely impact the functional and psychological status of the survivor.1,2

Evidence of cancer, specifically an osteosarcoma, has been found in mummies from ancient Egypt, with the Edwin Smith papyrus providing our oldest known description of a cancerous tumor.3 Hippocrates described cancer in detail and used the Greek terms "carcinos" and "carcinoma" to refer to chronic ulcers or growths that seemed to be malignant tumors. Although the word cancer is old, cancer as a frequently diagnosed disease is a relatively new disease. As life expectancy lengthened early in the 20th century, cancer diagnoses became increasingly common. Today, about 77% of all cancers are diagnosed in persons older than 55 years, with the number of cases increasing with increasing age.3 Improved screening, diagnostic testing, and treatment options have increased the 5-year survival rate of all cancer survivors to approximately 66%. The American Cancer Society estimates that there are approximately 14.5 million cancer survivors alive today, and this number is expected to increase to almost 19 million by 2024. Of these survivors 72% are older than 60 years.4

The success in increasing cancer survivorship is tempered by the recognition that virtually all cancer treatments carry with them a risk for sustained and persistent disease-related health problems including pain, neuropathy, fatigue, cardiovascular compromise, lymphedema, cognitive changes, depression, and reduced functional capacity.1,2 For the vast majority of cancer survivors, the temporal emergence of these treatment/disease-related morbidities is superimposed on the well-recognized morbidities associated with the aging process. This confluence of these health challenges in our elders is, perhaps, best described by emerging data, which demonstrate that the physiologic age of older cancer survivors often exceeds their chronological age.5 Older cancer patients are aging prematurely, are frail, and, as a result, are carrying a heavier symptom burden than their age-related healthy counterparts.5,6 This interface between cancer and aging is slowly but increasingly recognized, and Kagan7 suggests that "gero-oncology" should be used to identify this interface. Combining a geriatric focus with an oncology focus provides a way to identify vulnerable older survivors and develop individualized treatment plans, facilitate survivor independence, plan interventions, and decelerate the decline into frailty.8

The rehabilitation approach to the treatment of cancer originated with the National Cancer Act of 1971. This legislation declared cancer rehabilitation to be a national health care objective and directed funds to the development of training programs and research projects. Today, cancer rehabilitation is recognized as requiring a multidisciplinary treatment approach, and, as noted above, members of the treatment team would certainly benefit their patients by also having skills in geriatrics. The purpose of this special issue of Topics in Geriatric Rehabilitation was to introduce geriatric rehabilitation professionals to treatment interventions specific to a cancer diagnosis, new and potentially useful interventions and treatable comorbidities often found in the older cancer survivor. This task has been undertaken in an effort to reduce the symptom burden experienced by the cancer survivor thereby improving the quality of life of both the survivor and his or her caregiver.

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