By Eugenie Muchetu
Harare, (New Ziana) –Genetics are known to play a significant role in the development of cancer, accounting for an estimated 5 to 10 percent of all cases, with certain inherited mutations markedly increasing the risk of developing various types, making family history and testing critical factors in understanding vulnerability to the disease.
The National Cancer Institute of the United States of America notes that cancer is a genetic disease, caused by changes in genes that control the way cells grow and multiply.
Cells are the building blocks of human bodies and each one carries a copy of the genes, which act like an instruction manual. Genes are sections of DNA (deoxyribonucleic acid, the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA) that carry instructions to make proteins.
Scientists have identified hundreds of DNA changes, also called variants, mutations, or alterations, that help cancer form, grow, and spread.
Dr Nothando Christagirl Mutizira, Head of the Oncology Radiotherapy Department at Parirenyatwa Group of Hospitals, told New Zian that genetics play a significant role.
“Genetics plays a significant role, accounting for 5–10 percent of all cancers. For instance, mutations in genes like BRCA1 and BRCA2 can substantially increase the risk for breast and ovarian cancer. However, most cancers—about 90 percent—are not inherited,” she said, adding that a family history of certain cancers can indicate a genetic predisposition.
Inherited genetic changes can be passed down if present in a parent’s egg or sperm cells with, for example, if a parent passes a mutated BRCA1 or BRCA2 gene to their child, she will have a much higher risk of developing breast and several other cancers.
That is why cancer sometimes appears to run in families as up to 10 percent of all cancers may be caused by inherited genetic changes. Importantly, inheriting a cancer-related genetic change does not mean one will definitely develop cancer—it means the risk is increased.
Genetic testing identifies mutations and if a cancer diagnosis reveals a hereditary mutation, it can influence treatment options. Even for those without cancer, testing is important—especially with a family history—because it can guide preventive steps or early detection when treatment is most effective.
Identifying mutations can also help family members manage their own risks and in Zimbabwe, genetic testing for people without cancer is not yet widespread, underscoring the need to encourage families with cancer histories to seek testing.
A well-known example is actress Angelina Jolie, who underwent a double mastectomy as a preventative measure after discovering she carried a BRCA1 mutation.
Her mother died of ovarian cancer at age 56 and her decision highlights the importance of genetic testing and informed decision-making in cancer prevention, with her story empowering many women to take proactive steps regarding their health, emphasizing awareness and education about genetic risks.
Harvard Health Publishing reports that in the general population, about 12 out of 100 women (12 percent) will develop breast cancer during their lifetime while among women with harmful BRCA1 or BRCA2 mutations, as many as 60 out of 100 (60 percent) will develop breast cancer.
Women with at least two close relatives—a mother, sister, or daughter—who have had breast or ovarian cancer are also at much higher risk while men with these mutations face increased risk of breast cancer as well.
There are two main types of genetic testing, namely Somatic, which is done on the cancer cells themselves to learn about the cancer, helping doctors plan treatment and predict how well the cancer might respond, and Germline, which looks for inherited mutations present from birth that put a person at greater risk for cancer and should be encouraged for people with a family history of certain cancers.
Sister Irene Holland (70) of the Sisters of Nazareth recounted that she was first diagnosed with ductal cancer in 1997 in London. With a family history—her sister later developed breast cancer and her father died of lung cancer—she has undergone multiple mastectomies over three decades.
She has been on tamoxifen, a drug that blocks estrogen’s effects on breast tissue, keeping her cancer in remission for 17 years.
Dr Mutizira explained that recent years have seen advancements in cancer treatment including in radiotherapy techniques, which have allowed for more precise targeting of tumors.
There is also growing access to newer chemotherapy agents and hormonal therapies, with the introduction of the national HPV vaccination program being a monumental advancement in primary prevention for cervical cancer.
Preventive measures in Zimbabwe include the HPV vaccination program for girls, public health campaigns promoting abstinence from smoking, healthy diets, physical activity, and awareness about early detection through screening programs such as VIAC for cervical cancer and breast self-examinations.
“It is critically important. Education empowers individuals to recognize early warning signs, adopt healthier lifestyles, and participate in screening programs. An informed public is the first line of defence in the fight against cancer, as early detection dramatically improves treatment outcomes,” said Dr Mutizira.
“Diets low in fruits and vegetables and high in processed meats and fats are linked to an increased risk for several cancers, including colorectal and stomach cancers,” she added.
While women with inherited mutated genes face a very high chance—up to 60 percent—of developing cancer, awareness and encouragement for genetic testing are essential.
Frequent screenings and consultations with doctors can minimize risk, help catch cancer early, and improve treatment options while ultimately, education, prevention, and access to testing remain the strongest tools in reducing the burden of cancer.
New Ziana
