Cancer predisposition refers to an increased likelihood of developing certain types of cancer. This indicates a greater chance compared to the general population, often stemming from specific biological factors, with genetics playing a significant role. When a person has cancer predisposition, their body’s normal protective mechanisms against uncontrolled cell growth might be less effective. Understanding this helps individuals and healthcare providers recognize when someone might benefit from tailored prevention or early detection strategies.
What is Cancer Predisposition
Cancer predisposition primarily involves inherited changes, often called mutations or pathogenic variants, in specific genes. These genes regulate cell growth and division, or repair damaged DNA, acting as tumor suppressors. When altered, they may not function correctly, increasing the chance of cells growing uncontrollably and forming tumors. For example, mutations in genes like BRCA1 and BRCA2 increase the risk of breast and ovarian cancers.
These inherited genetic changes are present in nearly every cell from birth. This differs from sporadic cancer, which arises from genetic changes acquired during a person’s lifetime due to environmental factors, aging, or random errors in DNA replication. Inherited cancer predisposition syndromes account for about 5% to 10% of all cancers. While an inherited gene change increases risk, lifestyle and environment still influence whether cancer develops.
How Inherited Risk is Identified
Identifying inherited cancer risk begins with a detailed assessment of an individual’s family health history. Healthcare providers gather information about close blood relatives, including parents, siblings, children, grandparents, aunts, uncles, and first cousins, noting any history of cancer. This includes specific cancer types, ages at diagnosis, affected body parts, and any prior genetic testing results. Patterns such as multiple relatives with the same or related cancers, early-onset cancers, or rare cancer types within a family can suggest an inherited predisposition.
Following the family history review, genetic counseling is recommended. A genetic counselor, or another healthcare professional trained in cancer genetics, assesses the likelihood of inherited cancer risk based on the collected information. During this session, the counselor explains how increased cancer risk can be inherited and discusses the potential benefits, risks, costs, and limitations of genetic testing. They help individuals understand the medical and psychological implications of test results.
Genetic testing involves analyzing a small sample of bodily fluid or tissue, such as blood or saliva, to look for specific inherited genetic changes. These tests can identify known mutations that increase cancer risk. While a positive result confirms an inherited predisposition, a negative result does not always rule out a genetic risk, as not all genetic changes can be detected, or the specific mutation in a family might not yet be known. Multigene panels, which analyze dozens of genes simultaneously, are used, especially when there isn’t a known mutation in the family, or to test for recently discovered genes.
Steps for Managing Inherited Risk
Managing inherited cancer risk involves a personalized program developed in consultation with healthcare providers. One strategy is enhanced surveillance, involving more frequent and specialized screenings to detect cancer at its earliest, most treatable stages. For example, individuals with BRCA1 or BRCA2 gene mutations may undergo annual magnetic resonance imaging (MRI) and mammography for breast cancer screening. This intensified screening aims for early detection.
Risk-reducing surgeries can significantly lower cancer risk. For individuals with BRCA1/2 mutations, a risk-reducing bilateral salpingo-oophorectomy (removal of ovaries and fallopian tubes) is considered the gold standard for preventing ovarian cancer, reducing risk by 80-96%. Risk-reducing mastectomy, the surgical removal of healthy breast tissue, can reduce breast cancer risk by at least 90% in women with BRCA1 and BRCA2 mutations. These surgeries are often considered after childbearing.
Chemoprevention involves medications to reduce cancer development. For instance, selective estrogen receptor modulators (SERMs) like tamoxifen or raloxifene can reduce breast cancer incidence in high-risk women. Tamoxifen can reduce breast cancer occurrence by about 32% in high-risk individuals and the risk of a second breast cancer in BRCA1 and BRCA2 carriers by approximately 44%. Other SERMs, such as arzoxifene and lasofoxifene, also reduce invasive breast cancer incidence.
Lifestyle choices complement these medical interventions in managing inherited cancer risk. While genetic predisposition is a significant factor, healthy behaviors can further influence overall risk. This includes a balanced diet, regular physical activity, and avoiding known carcinogens like tobacco. Studies suggest physical activity can reduce breast cancer risk in women with BRCA1 and BRCA2 mutations by approximately 20%, highlighting the role of behavioral factors.