The very first step in evaluating an individual's risk for cancer is to assess the individual's concerns and reasons for seeking counseling to guarantee that personal needs and priorities will be met in the counseling process. The next step is to collect the pertinent medical, family, and personal information to assemble a risk profile and begin to explore options for dealing with the risk. A detailed family history is the cornerstone of effective genetic counseling. The counselor begins with the health of the proband and proceeds outward to include first-, second-, and third-degree relatives on both the maternal and paternal side. In addition to cancer diagnoses by primary site, age at onset, bilaterality when appropriate, and current age or age at death are recorded. Cancer diagnoses are validated by obtaining medical records, pathology reports, or death certificates when possible. Other medical and genetic conditions that may predispose individuals to cancer risk (e.g., Crohn's disease and colon cancer, atypical ductal hyper-plasia, and breast cancer) should also be noted. It is important to include information about family members unaffected with cancer to appreciate the penetrance of the disease and overall patterns of inheritance. Information about possible consanguinity is also valuable, particularly in the considera tion of recessive disorders. Ancestry and ethnicity should be recorded, as some inherited conditions are more common in certain ethnic groups (founder effects).
Family history data are graphically represented on a pedigree, which follows standard nomenclature to illustrate family relationships and disease information17 (Figure 25.1). Factors that limit the informativeness of the pedigree are small family size, early deaths in family members precluding the possibility of developing adult diseases, prophylactic surgeries that remove an organ from subsequent risk of cancer (e.g., total hysterectomy for uterine fibroids where the ovaries are also removed), and incomplete information about the health of family members. The degree of accuracy of reporting cancer diagnoses in relatives varies by how close the relatives are to the proband, with lack of information about specific cancer diagnoses in older second and/or third generations being a particularly common problem encountered in pedigree generation.
The collection of a targeted medical history of the proband serves two purposes: (1) the identification of premalignant conditions associated with subsequent cancer progression and (2) the estimation of other risk factors that may interact with or modify familial cancer risk. A careful reproductive history is pertinent to a number of common cancers in women. Exogenous hormone use and other medication history is also of value. The knowledge of other medical conditions may affect the management recommendations for reducing cancer risk. Caution about the use of exogenous estrogens in women with a familial predisposition of breast cancer, for example, may be tempered by a strong personal or family history of osteoporosis.
Environmental exposures and lifestyle factors, such as smoking, diet and alcohol use, and type of occupation may contribute to the overall estimation of risk, and their identification may offer opportunities for lifestyle changes to alter risk. Although occupational exposures to carcinogens such as benzene or asbestos account for a relatively small proportion of cancer, their recognition is very important in elucidating patterns of cancer and in eliminating other causes among exposed individuals. Environmental exposures and lifestyles are often shared by family members and must be recognized when assessing hereditary patterns of cancer. Finally, a record of past cancer screening practices establishes a history of health promotion behavior and will help guide the counselor in making reasonable and appropriate health recommendations.
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