Can cancer be inherited?
Cancer cannot be inherited, but the risk of developing cancer can be. That is, the tendency to develop cancer runs in some families, as has been shown with the discovery of specific abnormal genes that make a woman more likely to develop breast cancer under certain conditions. The presence of genetic abnormalities doesn’t mean that the disease itself is hereditary, however.
In cancers with a hereditary component, an abnormal gene is passed from parent to child. However, a cell becomes abnormal during a person’s lifetime because of additional changes in the DNA such as a spontaneous gene mutation or a cancer-causing agent (carcinogen) in the environment. Asbestos, cigarette smoking, and some pesticides are well-known carcinogens. According to die information that is currently available, the majority of cancers appear to be the spontaneous variety rather than the inherited kind linked to predisposition.
Another extremely important point to remember is that many people who have either an inherited cancer gene or a gene that has mutated spontaneously do not develop the disease. The abnormal gene might mean a tendency to develop a cancer, but additional mutations must occur before a tumor can develop. In fact, most cancer cells have a number of different defects in their DNA. Thus, one abnormal gene rarely causes cancer.
Genetic Counseling Genetic counseling is a new and rapidly evolving field that is important for parents who are concerned that they may pass a disease, such as sickle-cell anemia, cystic fibrosis, or cancer, to their children. Genetic counselors interview couples about their family histories to determine what type of disease may have occurred in relatives. For example, because some cancers, such as breast and ovarian cancer, go together, women whose relatives have developed either type of cancer at a young age may be at risk for either type of cancer. Under certain circumstances, a genetic counselor may recommend that a person have his or her genes examined in the laboratory. If a genetic abnormality is identified, the counselor can then discuss the potential risks for them or their children, the need for regular screening, and preventive measures.
Although genetic counseling can be helpful in some cases, it also raises a number of difficult questions:
- Can something be done to prevent the cancer? If nothing can be done to prevent the cancer, can more frequent testing for the cancer, and early detection, at least make a difference in terms of treatment and recovery? – Will the information make the person’s life better or worse? That is, will worry about the possibility of developing cancer dominate the person’s thoughts, so that his or her quality of life is diminished? – Will the information be kept confidential, so that insurance companies and employers don’t have access to it? (Insurance companies and employers may discriminate against a person if genetic testing indicates that he or she has inherited a tendency to develop cancer.)
Because questions such as these sometimes have unsatisfactory answers, many people, understandably, avoid genetic testing. The decision to undergo genetic testing is a difficult and personal one. It should be made only after discussion with an expert in oncology or genetic counseling.
