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Make the Diagnosis: Cancer, Family History

Prior Probability

The prior probability of a family history of any carcinoma depends on the specific cancer. The general rates are as shown in Table 20-6.

Table 20-6Prevalence of Family History of Some Common Cancers

Population for Whom a Family History of Cancer Should Be Considered

A family history that addresses cancer should be obtained from all patients. However, the field of genetics and personal risk assessment is changing rapidly, and physicians will need to get further education based on new data that describe a myriad of genetic associations with cancer. Online assessment tools can help patient assess their individual risk (; accessed May 29, 2008). The BRCA mutation, a particularly strong risk factor for breast or ovarian cancer, has specific online resources for assessing risk, although all risk assessments depend on accurate information from the patient ( or; accessed May 29, 2008).

Detecting the Likelihood of a First-Degree Relative With Cancer

A healthy patient who reports no family history of cancer will most likely be correct. However, even among patients with a personal history of cancer, the accuracy of a positive report of cancer in first-degree relatives may sometimes require confirmation, depending on the specific surveillance or genetic screening plan (see Tables 20-7 and 20-8).

Table 20-7Likelihood Ratio of a Healthy Patient's Reported Family History for Cancer
Table 20-8Likelihood Ratio of an Affected Patient's Reported Family History for Cancer

Reference Standard Tests

Verification of cancer from the first-degree relative's medical record, physician, population cancer registry, or autopsy.

Original Article: Does This Patient Have a Family ...

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