Cancer Genetics Risk Assessment and Counseling (PDQ®): Genetics - Health Professional Information [NCI] - Components of the Risk Assessment Process
Both multimedia-based (e.g., Internet) and print-based (e.g., family history questionnaires) tools are currently available to gather information about family history. In the United States, many are written at reading grade levels above 8th grade, which may reduce their effectiveness in gathering accurate family history information. On average, print-based tools have been found to be written at lower reading grade levels than multimedia-based tools.
Standards of pedigree nomenclature have been established.[31,32] Refer to Figure 1 for common pedigree symbols.
Figure 1. Standard pedigree nomenclature. Common symbols are used to draw a pedigree (family tree). A pedigree shows relationships between family members and patterns of inheritance for certain traits and diseases.
Documentation of a family cancer history typically includes the following:
- A minimum of three generations of relatives on both the maternal and paternal sides of the family. Information on multiple generations helps to demonstrate inheritance patterns. Hereditary cancer can be inherited from either the maternal or paternal side of the family and is often an adult-onset disease.
- Race, ancestry, and ethnicity of all grandparents. This may influence decisions about genetic testing because specific mutations in some genes are known to occur with increased frequency in some populations (founder effect).
- Information about seemingly unrelated conditions, such as birth defects, atypical skin bumps, or other nonmalignant conditions of children and adults that may aid in the diagnosis of a cancer susceptibility syndrome.
- Notation of adoption, nonpaternity (the biologic father should be included in the pedigree), consanguinity, and use of assisted reproductive technology (e.g., donor egg or sperm), when available.
A three-generation family history includes the following:
- First-degree relatives (e.g., children, brothers and sisters, and parents).
- Second-degree relatives (e.g., grandparents, aunts and uncles, nieces and nephews, grandchildren, and half-siblings).
- Third-degree relatives (e.g., first cousins, great aunts, and great uncles).
- Additional distant relatives are included if information is available, especially when there are known cancer histories among them.
For any relative with cancer, collect the following information:
- Primary site of each cancer, with supportive documentation of key cancers (if available) to confirm primary site and histology (e.g., pathology reports, clinical documents, and death certificates).
- Age at diagnosis for each primary cancer.
- Where the relative was diagnosed and/or treated.
- History of surgery or treatments that may have reduced the risk of cancer. For example, bilateral salpingo-oophorectomy in a premenopausal woman significantly reduces the risk of ovarian and breast cancers. This may mask underlying hereditary predisposition to these cancers.
- Current age (if living).
- Age at death and cause of death (if deceased).
- Carcinogenic exposures (e.g., tobacco use and radiation exposure).
- Other significant health problems.