- Relationship Between Genes and Cancer
- Relationship between genes and cancer, overview
- What is mutation and what causes a mutation?
- Types of mutations
- How do mutations lead to cancer?
HOW DO MUTATIONS LEAD TO CANCER?
Gene mutations may occur when:
- Your pet carries a gene mutation from birth which could either be inherited from a parent or developed when it was in an embryo.
- Your pet encounters something that damages the genes, like UV radiation or different kinds of herbicides and pesticides.
- Your pet’s genes wear out and either lose their function or function defectively as your pet ages.
Under normal circumstances, the cell’s DNA repair proteins detect correct mutations. If the mutations go unrepaired, the cells receive signals to die through a process known as programmed cell death. However, if a cell has a defective repair mechanism, the mutation may go unnoticed, and the affected cells escape cell death. Avoiding programmed cell death is the hallmark feature of cancerous cells since the cells with damaged DNA survive and divide uncontrollably.
Cancer genes that control cell growth and can cause cancer are divided into three main categories:
- Proto-Oncogenes & Oncogenes: Proto-oncogenes are a class of genes responsible for turning normal cells cancerous when they are mutated. The mutated version of a proto-oncogene is called an oncogene. Proto-oncogenes and oncogenes function as on/off switches. Usually, a proto-oncogene is switched off; however, when it is switched on, it triggers cell growth by directing a cell to grow or divide. Oncogenes are always on, leading to uncontrolled cell growth, causing cancer.
- Tumour suppressor genes (TSGs): TSGs are normal genes that protect your pet against cancer by slowing down cell growth and division, repairing mistakes in DNA, and directing them to die in case of abnormal growth. Mutations in these genes cause the cells to grow out of control, causing cancer.
- DNA repair genes: DNA repair genes play a vital role in fixing genetic mistakes when DNA copies during multiplying. When the genes are mutated, correcting errors in oncogenes and tumor suppressor genes is more challenging, leading to cancer development.
Not all individuals carrying a cancer-causing gene mutation will develop cancer. For instance, two pups (or kittens) from the same parents could inherit the same gene mutation. Still, only one offspring may develop cancer because cancer-causing mutations carry different levels of risk. Mutations with a high risk are more likely to cause cancer in their offspring, while mutations with a low risk are less likely. It is the mutated gene that determines the level of risk. Reports show that canine mammary cancer, lymphoma, leukemia, and mast cell tumors result from genetic alterations. Similarly, lymphoma, mammary cancer, and mast cell tumors in cats are reported to result from genetic mutations.
Learning how mutations lead to cancer helps you understand your pet’s risk. Talk to your vet about your pet’s bloodline, what increases your pet’s chance of developing cancer, and treatment options after diagnosis. These discussions will help you and your beloved furry friend enjoy many happy tomorrows together.

The Pet Cancer Foundation’s Website Editorial team is comprised of veterinarians, veterinary oncologists, and veterinary technicians, as well as scientific writers and editors who have attained their PhD’s in the life sciences, along with general editors and research assistants. All content found in this section goes through an extensive process with multiple review stages, to ensure this extended resource provides pet families with the most up-to-date information publicly available.
The team listing of those contributing to the information on this page is here:
Keep Your Pets Healthy Editorial Team
Last Updated: November 13, 2022
The Pet Cancer Foundation’s medical resource for pet owners is protected by copyright.
For reprint requests, please see our Content Usage Policy.
The Pet Cancer Foundation’s Medical Illustration team is comprised of medical illustration specialists and graphic designers that work in consultation with our team of experts to create the medical art found throughout our website. Though not all medical concepts require the assistance of imagery, when a page does contain a medical illustration, credit to the artist and our medical art director will be noted here.
The Pet Cancer Foundation’s medical imagery is protected by copyright and cannot be used without prior approval that includes a mutually signed licensing agreement. Please review our Content Usage Policy.
The following sources were referenced to write the content on this page:
Adamson, ED 1987, ‘Oncogenes in development’, Development, vol. 99, no. (4), pp. 449–471.
Haga, S, Nakayama, M, Tatsumi, K, Maeda, M, Imai, S, Umesako, S, Yamamoto, H, Hilgers, J & Sarkar NH 2001, ‘Overexpression of the p53 gene product in canine mammary tumors’, Oncol Rep, vol. 8, no. 6, pp. 1215-1219.
Lin J, Kouznetsova VL, Tsigelny IF. Molecular Mechanisms of Feline Cancers. OBM Genetics 2021; 5(2): 131;
London, CA, Kisseberth, WC, Galli, SJ, Geissler, EN & Helfand SC 1996, ‘Expression of stem cell factor receptor (c-kit) by the malignant mast cells from spontaneous canine mast cell tumours’, J Comp Pathol, vol. 115, no. 4, pp. 399-414.
Mealey, KL, Minch, JD, White, SN, Snekvik, KR & Mattoon, JS 2010, ‘An insertion mutation in ABCB4 is associated with gallbladder mucocele formation in dogs’, Comp Hepatol, vol. 9, no. 6, pp. 1-7.
Pang, L & Argyle, D 2016, ‘Veterinary oncology: biology, big data and precision medicine’, Vet J, vol. 213, pp. 38-45.
Setoguchi, A, Sakai, T, Okuda, M, Minehata, K, Yazawa, M, Ishizaka, T, Watari, T, Nishimura, R, Sasaki, N, Hasegawa, A & Tsujimoto H 2001, ‘Aberrations of the p53 tumor suppressor gene in various tumors in dogs’, Am J Vet Res, vol. 62, no. 3, pp. 433-439.
Weinstein, IB & Joe, AK 2006, ‘Mechanisms of disease: oncogene addiction—a rationale for molecular targeting in cancer therapy’, Nat Clin Pract Oncol, vol. 3, no. 8, pp. 448–457.
Wiese, DA, Thaiwong, T, Yuzbasiyan-Gurkan, V & Kiupel, M 2013, ‘Feline mammary basal-like adenocarcinomas: a potential model for human triple-negative breast cancer (TNBC) with basal-like subtype’, BMC Cancer, vol. 13, no. 403, pp. 1-12.
Wu, F.Y.; Iijima, K.; Tsujimoto, H.; Tamura, Y.; Higurashi, M. Chromosomal translocations in two feline T-cell lymphomas. Leuk. Res. 1995, 19, 857–860.
Yoshikawa, Y, Morimatsu, M, Ochiai, K, Ishiguro-Oonuma, T, Wada, S, Orino, K & Watanabe, K 2015, ‘Reduced canine BRCA2 expression levels in mammary gland tumors’, BMC Vet Res, vol. 11, no. 159, pp. 1-8.
The Pet Cancer Foundation’s medical resource for pet owners is protected by copyright.
For reprint requests, please see our Content Usage Policy.