Having a “cancer gene” means inheriting a genetic variation that increases susceptibility to certain cancers. This predisposition does not guarantee a diagnosis, but signifies a higher lifetime risk compared to the general population. These genetic changes can disrupt normal cellular processes, making cells more prone to uncontrolled growth. Understanding this elevated risk allows for proactive strategies to monitor and potentially reduce cancer development.
Understanding Inherited Cancer Risk
Inherited cancer genes, or germline mutations, predispose individuals to cancer. These mutations are present in every cell from conception, passed down from a parent. They differ from somatic mutations, which are acquired during a person’s lifetime and are not inherited. While all cancers involve genetic changes, only about 5% to 12% are linked to these inherited alterations.
Many inherited cancer genes are tumor suppressor genes that regulate cell growth and division or repair damaged DNA. When mutated, these genes fail to perform their protective roles, allowing genetic errors to accumulate. For instance, BRCA1 and BRCA2 genes are involved in DNA repair; mutations in them significantly increase the risk of breast, ovarian, prostate, and pancreatic cancers. Genes like MLH1, MSH2, MSH6, and PMS2 are part of the mismatch repair system; mutations in them are associated with Lynch syndrome, elevating risks for colorectal and endometrial cancers.
Inheriting one of these mutations means an individual begins life with a “first hit” towards cancer development. This increases susceptibility, making them more likely to develop cancer, often at an earlier age. However, possessing such a gene does not mean cancer is inevitable, as additional genetic changes or environmental factors are typically required. The presence of an inherited mutation establishes a genetic predisposition, highlighting the importance of tailored surveillance and risk management.
Genetic Testing for Cancer Genes
Genetic testing typically discovers if one carries a cancer gene, often initiated after reviewing personal and family medical history. Candidates for testing include individuals with a strong family history of cancer, early-onset diagnoses (e.g., colon cancer before age 50), or specific cancer types like ovarian, male breast, triple-negative breast, pancreatic, or metastatic prostate cancer. These factors signal a higher likelihood of an underlying inherited genetic mutation.
Testing usually requires a small sample of blood or saliva, analyzed in a laboratory to identify specific genetic changes. Results fall into three categories: positive, negative, or a variant of uncertain significance (VUS). A positive result confirms a pathogenic mutation, while a negative result indicates no known cancer-predisposing mutations were found.
A VUS describes a genetic change with insufficient scientific data to classify it as harmful or benign. VUS results are common, especially with multi-gene panel testing, and typically do not guide medical management. Genetic counseling is crucial, providing information about testing risks, benefits, and limitations, helping individuals understand their results and their health implications.
Managing Elevated Cancer Risk
For individuals with an inherited cancer gene, proactive management strategies mitigate elevated risk. A primary approach is increased surveillance, meaning more frequent, specialized screenings than recommended for the general population. For example, women with BRCA1/2 mutations typically begin mammograms and breast MRIs at younger ages, sometimes as early as 25, and undergo them annually. Individuals with Lynch syndrome often start colonoscopies in their 20s or early 30s, repeating them every one to two years, significantly earlier and more frequently than average, to detect precancerous polyps or early-stage colorectal cancer.
Beyond enhanced screening, risk-reducing interventions offer additional protective measures. Preventive surgeries are a consideration, such as prophylactic mastectomy to reduce breast cancer risk, or salpingo-oophorectomy (removal of ovaries and fallopian tubes) to lower ovarian cancer risk in BRCA1/2 carriers. These are personal decisions made in close consultation with medical professionals, weighing benefits against potential impacts on fertility, body image, or menopausal symptoms. Chemoprevention, using medications like tamoxifen to reduce breast cancer risk, is another option for certain inherited conditions.
While medical interventions are central to risk management, healthy lifestyle choices complement these strategies. A balanced diet, regular physical activity, and avoiding tobacco use are general recommendations supporting overall health. These choices may help reduce cancer risk, even for those with genetic predispositions, by promoting a healthy cellular environment. The combination of surveillance, interventions, and lifestyle adjustments is tailored to each individual’s genetic mutation, health profile, and preferences, developed with their healthcare team.
Implications for Family Members
Discovering an inherited cancer gene has significant implications for biological family members. Since these mutations are passed down, first-degree relatives (parents, siblings, children) of a person with a positive genetic test result each have a 50% chance of inheriting the same alteration.
“Cascade testing” allows targeted genetic testing for at-risk relatives once a specific mutation is identified in one family member. This approach identifies those who could benefit from increased surveillance or risk-reducing measures, and spares those who test negative from unnecessary interventions.
Genetic counseling guides families through these discussions. Counselors help family members understand their risks, interpret test results, and explore management options. This support ensures decisions about testing and health management are made with comprehensive information and consideration.