Barbara Resnick, PhD, CRNP; and Sandra W. McLeskey, PhD, RN
The older population has increased by 3.2 million, or 9.4%, since 1995, and approximately 1 in 8 individuals (12.5% of the population) is older than 65 years.1
With increased age, it is well known that there is an increased risk for the development of cancer.1,2
Most new cancers and cancer deaths occur in persons older than 65 years.3
Readers are referred to specific comprehensive review articles related to the science of cancer and aging.4,5
Specifically, these reviews address the mechanisms of aging that affect the development and suppression of cancer.
In older adults, cancer affects life expectancy and has a major effect on quality of life. Moreover, older adults who experience cancer are likely to be living with additional comorbidities such as heart disease, diabetes mellitus, dementia, or arthritis. The associated comorbidities, life expectancy, and perceived health status of these individuals influence decisions regarding screening, treatment, and ongoing cancer surveillance and care.
The objectives of this article are to consider what is known about screening for cancer among older adults and to address how this knowledge can be applied to current clinical practice and to the direction of future research. Screening refers to testing in individuals who have not previously been diagnosed as having a malignancy. However, some consideration is also given to ongoing cancer surveillance, which includes patients who continue to undergo screening procedures (eg, mammography) but have already been diagnosed as having cancer.CANCER SCREENING
There are numerous published recommendations for cancer screening among older adults, and Medicare has specific guidelines for coverage of the recommended screening tests6-11
). However, the recommendations established by the United States Preventive Services Task Force (USPSTF)11
are the only ones that are solely evidenced-based. With regard to older adults, it is generally recommended that screening be based on the life expectancy of the individual, the risk vs benefit associated with screening, and the preferences of the patient or his or her caregiver.12-14
Recognizing the heterogeneity of older adults, it is critical to consider the overall health status of the individual.15,16
When comorbidity, functional status, and life expectancy are taken into consideration,17
evidence supports the effectiveness of screening for cancer among older adults.18,19
Moreover, most older individuals (particularly well-educated individuals of white race/ethnicity) realize the benefits of cancer screening and are willing to engage in screening tests.20
Similar findings have been noted by B. Resnick, PhD (unpublished data, 2007). However, it is apparent that adherence to screening guidelines for all older individuals may not always be in the best interest of the individual because the tests may result in unnecessary stress, morbidity, and even mortality without affecting the life span.16,21,22
Conversely, there may be a decrease in quality of life (eg, pain from a tumor or other consequences of a missed malignancy) associated with not screening a particular individual based purely on health status and life expectancy. For example, performing breast cancer screening in an 85-year-old woman in the upper quartile of health status and life expectancy (ie, those in better health with a >20-year life expectancy) is more likely to be beneficial for that particular individual compared with breast cancer screening in a 75-year-old woman in the lower quartile of health status and life expectancy (ie, those in worse health with a <3-year life expectancy).16Breast Cancer Screening
recommends a screening mammography (with or without clinical breast examination) every 1 to 2 years for women 40 years and older. There is insufficient evidence to recommend for or against routine clinical breast examination without mammography to screen for breast cancer.11
Mammograms optimally identify tumors when the breast tissue is fatty, as occurs in the postmenopausal woman. Fatty breast tissue has fewer areas of density (white areas on the mammogram) that can obscure a suspicious area (Figure
). For this reason, the sensitivity of mammography increases as a woman ages.7
Screening recommendations related to breast cancer do not address the potential risks of performing mammography in older adults. These risks include undergoing additional tests and biopsies associated with false-positive test results, emotional distress and anxiety, and exposure to futile evaluations and treatments.23,24
For example, if a breast malignancy is found in a frail older adult with limited life expectancy, treatment options may be limited and may engender significant morbidity or even mortality.
Mammography has a high false-positive rate and is unable to detect about 5% of breast cancers.7
Because of this, other screening modalities are being explored such as the use of dualenergy x-ray absorptiometry to accurately detect breast density25
and the use of breast density to help determine the risk of breast cancer.26-28
The measurement of breast density, along with other known risk factors associated with breast cancer diagnosis such as age, race / ethnicity, family history of breast cancer, a prior breast procedure, body mass index, natural menopause, the use of hormone therapy, and a false-positive mammogram in the past, can be used to help identify those at particular risk.28
Alternatively, magnetic resonance imaging has been used to detect breast cancer (particularly in situations in which mammography alone has poor sensitivity),29
to help identify age-related changes in the breast,30
or to detect local chest wall tumor recurrence after mastectomy.31
Magnetic resonance imaging is recommended by the American Cancer Society as an adjunct to mammography in women at high risk for breast cancer.27
However, there is no evidence to suggest the usefulness of this type of testing in older adults.32
Likewise, digital or computer-aided diagnostic mammography, while more accurate in identification of breast tumors in younger women, has not been shown to be advantageous for older women.33Mammography Surveillance Recommendations in Breast Cancer Survivors
There are approximately 2 million women with a known diagnosis of breast cancer, more than half of whom are older than 65 years.34
Most of these women had no metastatic disease at diagnosis but are at risk for local or systemic recurrence. In addition, after an initial diagnosis of breast cancer, a woman is at an approximately 2-fold increased risk for a second breast cancer, which may be in the same breast if breast-conserving surgery was used or in the ipsilateral breast.35
Guidelines for follow-up include an annual history, a physical examination, and a surveillance mammogram.7
In a study23
that included a sample of 1846 older women with stage I and stage II breast cancer, there was a 0.69-fold decrease in the odds of breast cancer mortality with each additional surveillance mammogram and an almost one third reduction in the mortality rate. The protective association of a surveillance mammogram was strongest among those with stage I disease, those who had a mastectomy, and those in the oldest age group (>85 years). As with initial breast cancer screening, surveillance screening should consider the individual’s comorbidities, life expectancy, health status, and quality of life.Colorectal Cancer Screening
As summarized in Table 1, recommendations for colorectal cancer screening include the following screening options6,8,9,11,36,37
: annual fecal occult blood test, flexible sigmoidoscopy once every 4 years or once every 2 years if the patient is at high risk, or colonoscopy every 2 years if the patient is at high risk for colon cancer (no age limit). Barium enema can be a substitute for sigmoidoscopy or colonoscopy if this is more advisable for the patient. There is no evidence to support the recommendation of one type of screening procedure over another.
Given that 90% of all cases of colon cancer occur after age 50 years, all older adults are at risk. Screening for colorectal cancer focuses on identifying premalignant adenomatous polyps. It is believed that this type of polyp will progress from an adenoma to cancer during 5 to 10 years. Therefore, screening for colon cancer has a particular advantage in that it is more likely to prevent the occurrence of cancer rather than just to identify disease once it is present.
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