You might be aware that several factors play a role in the development of cancer in the body, and genes inherited from the parents are one of them. Even a slight change in the gene can result in an alteration of some bodily functions leading to cancer. Although genetic mutations may cause cancer, they account for only 5 to 10 per cent of cancers. You will get to know about some cancers that may be inherited here.

Inheritance of cancer

Inheriting the genes from one's family can be pretty disturbing for anyone. People do fear the passing of genes from generation to generation. So, if you ask if cancer is hereditary, the answer is yes, but it's like one out of ten people only. On the other hand, the presence of genetic mutations puts at a higher risk of developing cancer.

Sometimes, family members get the same type of cancer. It may not be due to the inheritance of genes. It may be due to their similar lifestyle choices and the same environmental conditions. For example, they may share the same habits like alcohol consumption, smoking, etc.

Also Read: Cancer Is Hereditary - A Myth Or A Reality?

Influence of heredity on cancer and other facts

Cancer is hereditary or not, it is unwelcome worldwide. It results in several deaths every year. Thus, the patients must select only the best cancer treatment. Below are a few facts about cancer:

• About 22% of cancer deaths are caused due totobaccouse
• Approximately 10% of cancer deaths are due to obesity, lack of physical activity, poor diet, or excessive consumption ofAlcohol.
• Only 5-10% of the cases of cancer are due to genetic defects inherited from the parents.
• About 14.1 million new cases are reported every year.
• In 2015, approximately 90.5 million people had cancer.

Types of genetic mutation

Cancer is an uncontrollable and abnormal growth of the cells in the body. Such mutations can cause the unusual growth of the cells. Genetic mutation can alter the functioning of the cells. For example, a mutation in the gene can affect cell growth and cell division. It can lead to very rapid cell division or very sluggish cell division. It all depends on what gene is affected. This kind of mutation can be inherited or passed on from the parents to their children.

Let us talk about the type of mutation that can occur in the genes:

• Inherited gene mutation: These kinds of mutation occur in the egg cell or sperm. When the fetus develops from such egg cells or sperm, the mutation transfers to the baby or fetus. So, the child is at risk of getting the disease due to the mutation, and he or she can even pass it to the next generation.
• Acquired gene mutation: These kinds of mutation occur in the cells of the body other than the reproductive parts. It may result from damage to the DNA due to exposure to several environmental factors. It might be passed to the cells formed from the cells with mutations. So, not all the cells in your body can be affected. Since mutations are not present in the reproductive cells, they stay within a single generation.

What if you inherit mutated genes?

If you have any mutated genes, you are at an increased risk of getting cancer. But you should note that the mere inheritance of the genetic mutation linked to cancer is not enough. You inherit two sets of the same genes from both of your parents. If one of the genes is mutated while the other one is not mutated and functional, it is less likely that you will develop cancer. It happens because the other gene takes care of your bodily and cellular functions. And hence, it keeps you away from getting this disease. Unfortunately, the other gene is also mutated, or gets harmed by exposure to any carcinogens, cancer may affect you.

How can genes cause cancer?

A structure called the nucleus is present inside every cell of the body. It controls the cell. Within the nucleus, there are 23 pairs of chromosomes which comprise genes. Genes are the coded messages that instruct the cell on how to behave.

Alltypes of cancerare developed because of a fault or a mutation in one or more genes in a cell. In most cases, a gene becomes cancerous if it has 6 or more faults. The cell might stop functioning properly due to these faults. It might become cancerous and divide uncontrollably.

The majority of the gene faults develop during the lifetime of a person. The gene faults might happen due to random mistakes when the cells are dividing. However, some (5-10%) might be inherited from the parents. The gene faults might also occur due to exposure to cigarette smoke or other carcinogens. These genes are not inherited and cannot be passed from the parent to the offspring.

How to identify if cancer may be inherited

The first thing to notice is the number of cancer cases in your family. Your family may have a history of the family members affected by the same or different types of cancer. You may look at these hints too:

• Family members having the same type of cancer
• Too many occurrences of cancer
• Any family member may have more than one type of cancer
• Your siblings with cancer
• Cancer cases in many generations

Also Read: How Cancer Runs In Family

Genetic Mutations and Inherited Cancer Syndrome

Cancer cases due to the inheritance of genetic mutation are about 5 per cent. Many genetic mutations can lead to cancer. You can link these mutations to a specific cancer type. Some of them are:

BRCA1 and BRCA2

These mutations can make a woman more susceptible to breast and ovarian cancer. On the other hand, a man with this genetic mutation has an increased risk of getting breast and prostate cancer.

Cowden Syndrome

A gene called PTEN is responsible for this syndrome. If a woman has this mutation, then she is more likely to develop breast and uterine cancer than other women. This genetic mutation also increases the risk of getting thyroid cancer in both men and women.

Familial Adenomatous Polyposis

A mutation in the APC gene may lead to this syndrome. This mutation puts you at an increased risk of getting colorectal cancer and brain tumours.

Li-Fraumeni Syndrome

Li-Fraumeni syndrome is very rare. Most people with this syndrome have a mutation in the gene TP53 gene. This mutation can increase the risk of many types of cancer, such as soft tissue sarcomas, breast cancer, leukaemia, lung cancer, brain tumours, and adrenal gland cancer.

Lynch syndrome

This syndrome can increase the risk of colorectal cancer. The mutation can be in the genes like MLH1, MSH2, MSH6, or PMS2.

Are cancers due to inherited genes common?

Most cancers are not hereditary. Gene changes due to radiation and other factors are the most common cause of cancer than hereditary ones. Environmental factors also play a significant role in cancer. Less than 0.3% of the population carry a genetic mutation that has a detrimental effect on the risk of developing cancer. These genes cause less than 3-10% of cancer.

Types of Hereditary Cancer

A few types of hereditary cancer, in which inherited gene mutations have been discovered are

• Adrenal gland cancer
• Bone cancer
• Breast cancer
• Fallopian tube cancer
• Ovarian cancer
• Prostate cancer
• Skin cancer
• Testicular cancer

Other factors that can cause cancer

Most cancers are due to lifestyle and environmental factors. Environmental factors refer to those factors which are not genetically inherited. They can be lifestyle or behavioural factors. This is where the importance of preventive care comes into play. Common factors that lead to cancer death are tobacco (around 25-30%), obesity (30-35%), radiation, and infection (approximately 15-20%). Below are the causes that could lead to the development of cancer-

• Chemicals:Exposure to carcinogens is linked to the development of specific types of cancer. For example, Tobacco smoke is a cause of 90% of Lung Cancer cases.
• Diet and physical activity:Excessive body weight is linked to the development of many cancers. A high-salt diet might result in gastric cancer.
• Infection:Around 18% of cancer deaths are linked to infectious diseases.
• Radiation:Radioactive material and exposure to UV radiation increase the risk of cancer.
• Physical agents:Some agents cause cancer through their physical effects. Continuous exposure to asbestos can result in mesothelioma.

Thus, most factors that might result in developing cancer are environmental rather than hereditary. However, some cancers are hereditary.

Genetic testing

As said earlier, cancer can happen due to a variety of reasons. You likely want to do genetic testing to test whether you have any genetic mutations. Genetic testing can surely give you more insight into your genetic makeup and also inform you of any inherited mutated genes. But it may not be necessary in your case. So, you should talk to your specialist before doing any genetic testing. Your doctor will ask you about your family's cases of cancer. If your specialist feels the need for genetic testing, your other family members might have to give the same test. Genetic testing gives comprehensive information about your genes rather than a simple yes or no answer. So, you will need a genetic counsellor to guide you through the results.

Summing up

Cancer does happen due to the inheritance of genetic mutations. But in most cases, it is not the cause of getting this disease. Only five to ten per cent of cancer cases are due to mutations in the gene. Still, you should be aware of the possible risk factors to stay a step ahead.

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Reference:

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2. Shiovitz S, Korde LA. Genetics of breast cancer: a topic in evolution. Ann Oncol. 2015 Jul;26(7):1291-9. doi: 10.1093/annonc/mdv022. Epub 2015 Jan 20. PMID: 25605744; PMCID: PMC4478970.