"One of the most effective tools to identify individuals at increased risk of cancer is to ascertain their family history. For example, having one or more close relatives with colorectal cancer increases risk from 2-fold to 6-fold. Individuals at increased risk of colorectal, breast, or prostate cancer due to family history are recommended to begin screening for these cancers earlier and in some cases using more sensitive methods than average-risk individuals," according to background information in the article. It is recommended that primary care clinicians collect a detailed family cancer history including age at diagnosis for affected first- and second-degree relatives. Little is known about how often clinically important changes in cancer family history occur over time that could change individual's risk and the need for earlier or intensive screening.

Argyrios Ziogas, Ph.D., of the University of California-Irvine, and colleagues conducted a study to quantify how often clinically significant changes in family history of breast, colorectal, or prostate cancer occur throughout adulthood. The study included an examination of baseline and follow-up family history data from participants in the Cancer Genetics Network (CGN), a U.S. national population-based cancer registry, between 1999 and 2009. Participants included adults with a personal history, family history, or both of cancer enrolled in the CGN through population-based cancer registries. Retrospective colorectal, breast, and prostate cancer screening-specific analyses included 9,861, 2,547, and 1,817 participants, respectively; prospective analyses included 1,533, 617, and 163 participants, respectively. Median (midpoint) follow-up was 8 years. The primary outcomes measured included percentage of individuals with clinically significant family histories and rate of change over two periods: (1) retrospectively, from birth until CGN enrollment and (2) prospectively, from enrollment to last follow-up.

The researchers found that retrospective analysis indicated that the percentages of participants who met criteria for high-risk screening based on family history at ages 30 and 50 years, respectively, were as follows: for colorectal cancer, 2.1 percent and 7.1 percent; for breast cancer, 7.2 percent and 11.4 percent; and for prostate cancer, 0.9 percent and 2.0 percent. "In prospective analysis, the numbers of participants who newly met criteria for high-risk screening based on family history per 100 persons followed up for 20 years were 2 for colorectal cancer, 6 for breast cancer, and 8 for prostate cancer. The rate of change in cancer family history was similar for colorectal and breast cancer between the 2 analyses," the authors write.

"Both analyses demonstrate that clinically relevant family history changes substantially during early and middle adulthood, particularly for colorectal and breast cancer, for which the percentage recommended for high-risk screening increases 1.5- to 3-fold between ages 30 and 50 years."

The researchers recommend that family cancer history should be updated at least every 5 to 10 years to appropriately inform recommendations for cancer screening.

Editorial: Recording, Interpreting, and Updating the Family History of Cancer

In an accompanying editorial, Louise S. Acheson, M.D., M.S., of Case Western Reserve University School of Medicine, Cleveland, writes that studies regarding screening must take into account risks, benefits, costs, and lead time issues.

"It is plausible but still unknown whether family history increases the likelihood that breast cancers, prostate cancers, or colon adenomas found by screening are clinically significant. An increase in the incidence of false-positive results and test-associated complications is a cost and potential harm of increased screening based on familial risk. Although some prospective data on the benefits of cancer screening based on familial risk are available, many estimates rely on extrapolation from small studies of patients with high-penetrance hereditary cancer susceptibility or from screening older patients at equivalent levels of risk."

Note: If no author is given, the source is cited instead.

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