Could cancer run in my family?

The human genome is a vast, complex instruction manual, and for far too long, our understanding of cancer has been built from an incomplete set of pages. Individuals of African descent, who possess the most extensive genetic and phenotypic variation among all humans, account for less than 3% of participants in global cancer genetics studies. This stark underrepresentation is not a simple oversight; it represents a profound gap in our collective knowledge, a blind spot that leaves a significant portion of the world's population with less effective treatments and a higher burden of disease. It’s time to fill that gap, and it starts with understanding the fundamentals of cancer at its most basic level: our genes. Cancer risk is the likelihood of developing cancer.

Is cancer a genetic disease?

Absolutely. At its core, cancer is a genetic disease. It’s not a condition you can "catch" like a cold, but rather a result of DNA damage and genetic changes that occur within a cell. These changes disrupt the normal control mechanisms that govern cell growth and division, leading to the uncontrolled proliferation of cells we know as cancer. While a small percentage of cancers are linked to inherited genetic changes, the vast majority are caused by changes that happen to a person's genes over their lifetime. This is why cancer risk increases with age.

Is cancer hereditary?

While cancer itself is not hereditary, a person can inherit a genetic change from a parent that significantly increases their cancer risk. Inherited changes, or mutations, are present in every cell of the body and can predispose an individual to certain types of cancer. These inherited changes are responsible for approximately 5% to 10% of all cancers. For example, a mutation in the BRCA1 or BRCA2 gene can dramatically increase a person's lifetime risk of breast and ovarian cancer. Most cancers, however, arise from genetic changes that are acquired, not inherited.

How do genetic risks manifest uniquely in African populations?

Because the African continent holds the highest genetic diversity in the world, genetic risks present differently here compared to Western nations. For instance, women of African descent are disproportionately diagnosed with Triple-Negative Breast Cancer (TNBC). This is an aggressive form of breast cancer that occurs at a much younger age, often behaves more aggressively, and lacks the three standard receptors used to target treatments. Furthermore, men of African ancestry experience a significantly higher incidence and mortality rate of prostate cancer, frequently developing it years earlier than men of other ancestral backgrounds. These realities underline the urgent need to look beyond Western-centric data and isolate the unique genetic signatures driving cancer across different African regions.

What is a family cancer syndrome?

A family cancer syndrome is a term used when cancer appears to run in a family due to an inherited genetic change. These syndromes are often characterized by specific types of cancer appearing in multiple family members, often at younger-than-average ages. When an inherited genetic mutation is identified as the cause, it provides a crucial clue for a family, allowing for proactive screening and prevention strategies. It's a powerful piece of information that can change the trajectory of an individual's health and the health of their relatives!

Navigating the complex realities of 'Variants of Uncertain Significance' (VUS)

When an individual undergoes genetic testing, the lab looks for specific deviations in their DNA sequence. However, due to the severe underrepresentation of African genomes in global databases, individuals of African descent are much more likely to receive a test result flagged as a Variant of Uncertain Significance (VUS). A VUS simply means the genetic test found a variation, but scientists do not yet have enough clinical data to determine whether that variation is harmless or a dangerous mutation that causes cancer. As a result, African patients are frequently left in a medical limbo—not knowing whether to take aggressive preventative action or rest easy, emphasizing the critical need for localized genetic databases.

Should I get genetic testing for cancer risk?

Genetic testing for cancer risk is not for everyone. It is a highly valuable tool for individuals who have a strong personal or family history of certain cancers. If your family has a known cancer syndrome or if multiple family members have been diagnosed with the same type of cancer, especially at a young age, genetic counseling and testing can provide life-saving information. This testing can help confirm a diagnosis, assess risk for other cancers, and inform a personalized prevention and screening plan. It's a proactive step that allows you to take control of your health with precise, data-driven insights.

How can I find out what genetic changes are in my cancer?

For those already diagnosed, genetic testing on the tumor itself, known as somatic or biomarker testing, can identify the specific genetic changes driving the cancer's growth. This information is invaluable! It can help your healthcare team choose the most effective treatment, as many new therapies are designed to target specific genetic mutations. This is the cornerstone of precision medicine using your tumor's unique genetic fingerprint to create a truly personalized treatment strategy.

Who can see my genetic test results?

The results of your genetic testing are a form of protected health information. The Genetic Information Nondiscrimination Act (GINA) prevents health insurers and employers from discriminating against you based on your genetic information. However, this protection has some limitations, so it's always wise to discuss the specifics with a genetic counselor. You have control over your results, and it's essential to understand who has access to this sensitive information and what protections are in place to ensure your privacy.

Overcoming structural and cultural barriers to genetic testing in Africa

While legislative protections like GINA exist in Western nations, the infrastructure for genetic privacy and healthcare equity varies considerably across the African continent. Accessing genetic testing in many African regions comes with distinct challenges. These include a shortage of certified genetic counselors, the high out-of-pocket costs of specialized diagnostic tests, and deep-seated cultural stigmas surrounding hereditary illnesses. In many communities, a cancer diagnosis is heavily misunderstood, mistakenly attributed to external spiritual causes or lifestyle failures rather than cellular DNA changes. Overcoming these barriers requires a community-centric approach that pairs medical access with comprehensive genetic literacy, bringing local leaders and healthcare workers into the conversation to demystify hereditary health.

How do genetic changes cause cancer?

Genetic changes cause cancer by disrupting the fundamental rules that govern cell behavior. Our genes contain the instructions for producing proteins that regulate cell growth, repair DNA damage, and trigger cell death. When genes are altered, these proteins can malfunction. Some mutations can activate "on" switches for cell growth (oncogenes), causing cells to divide uncontrollably. Others can break the "brakes" on cell division (tumor suppressor genes), allowing damaged cells to proliferate unchecked. A single genetic change is rarely enough to cause cancer; it typically takes a series of accumulated changes to transform a healthy cell into a cancerous one.

Study Helps Explain How Ovarian Cancer Forms

The formation of cancer is a complex process, and new research is constantly shedding light on its intricacies. For instance, a recent study has provided new insights into how ovarian cancer develops. This kind of research is critical because it helps us move from simply treating the disease to understanding its origins, paving the way for more targeted prevention and early detection strategies.

What kinds of genetic changes cause cancer?

The genetic changes that lead to cancer are varied and can range from tiny to massive.

1. Point Mutations: These are small, single-nucleotide changes in the DNA sequence, like a single typo in a long sentence. While small, a point mutation can have a major impact, altering a protein's function and potentially turning on a cancer-causing gene.
2. Chromosomal Rearrangements: These are large-scale changes where parts of chromosomes are deleted, duplicated, or moved to a different location. This can result in the loss of a tumor-suppressor gene or the creation of a new, fusion gene that promotes cancer growth.
3. Epigenetic Changes: These changes don't alter the DNA sequence itself but affect how genes are "read" and expressed. They can act like dimmer switches, turning gene expression up or down. For example, an epigenetic change could silence a tumor-suppressor gene, allowing a cell to become cancerous without any change to the underlying DNA.

These different types of genetic changes often work together to contribute to cancer development. The interplay of inherited and acquired genetic factors, coupled with environmental influences, is what makes cancer a truly personalized disease. Understanding these changes is the key to unlocking the future of cancer treatment and prevention.

Published 4th September 2025

References

American Cancer Society. The Genetics of Cancer: How Genes Influence Cancer Risk. Available at: https://www.cancer.org/cancer/risk-prevention/genetics.html

National Cancer Institute. Genetics of Cancer: How Genetic Changes Cause Cancer. Available at: https://www.cancer.gov/about-cancer/causes-prevention/genetics

MDPI Genes Journal. The Current State of Breast Cancer Genetics in Populations of African Ancestry (2025). Available at: https://www.mdpi.com/2073-4425/16/2/199

PMC Oncology. Genetic Contributions to Prostate Cancer Disparities in Men of West African Descent. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC8606679/