You must have remembered the nucleus, chromosomes and genes from your science class. Nucleus contains 23 pairs of chromosomes, and one chromosome in each pair comes from your father and another comes from your mother. Further each chromosome is made up of thousands of genes that makes us who we are.
Any change in the gene can alter its functions and lead to mutations. If any of your parents has a genetic mutation, there are 50% chances that this mutation will pass on to you. These faulty mutations can increase the risk of getting hereditary or genetic disorders and cancer is one of them.
We all know that cancer is caused by uncontrolled growth of body cells. It can be due to any harmful changes in the genes (gene mutations) which controls the growth and division of cells. Some of these mutations can be inherited one (hereditary) and others occur spontaneously as a result of environmental factors such as exposure to UV rays, chemical carcinogens, tobacco and smoking (acquired).
In this blog, we will discuss how cancer passes on from one generation to another, various inheritable cancers, your risk of getting an inheritable cancer and how to prevent or detect it at an early age?
How cancer runs into families?
In 5-10% of the cases, cancer runs into families, called inheritable or hereditary cancers. In these cases, an individual inherits a copy of mutated gene from one parent and another copy of normal gene from another parent. This mutated gene is called the cancer susceptibility gene.
If the normal copy of a gene also gets mutated, the cell can become cancerous. Thus individuals with a cancer susceptibility gene are at higher risk of developing cancer, but it is not important that anyone with a cancer susceptibility gene will develop cancer.
What is your risk of getting hereditary cancer?
When speaking of a risk of hereditary cancer, your medical health practitioner often assesses your family history or family tree to determine degree of relatedness. If an individual has an inherited mutation, there is 50% of passing on this mutated gene to his first degree relatives (Siblings, parents and children).
However, this risk decreases in second degree and third degree relatives which share 1/4th and 1/8th of the parent DNA. Second-degree relatives are uncles and aunts, grandparents, grandchildren, nephews and nieces whereas third-degree relatives include cousins, great grandparents, great-aunts and great-uncles.
Your risk of getting an mutated cancer causing gene increases, if:
- Your two or more relatives with the same type of cancer, on the same side of the family (either mother or father side)
- Several generations in your family are affected (such as grandfather, father and then son)
- Your relatives are affected by same type of cancer
- Your family members have cancer in young age (below 50)
- Your close relative has had 2 different types of cancer (such as women with both breast cancer and ovarian cancer)
What are the most common hereditary cancers?
There are many hereditary cancers which result from a mutation in a specific gene. Below are some common hereditary cancer syndromes such as:
1) Hereditary Breast and Ovarian Cancer
In some families, women develop breast and ovarian cancer at a young age due to an inherited mutation in the BRCA1 or BRCA2. Women with these genetic mutations have a higher risk of developing breast and ovarian cancer, but this risk increases even more with BRCA1 genetic mutation. Along with breast and ovarian cancer, mutations in the BRCA1 and BRCA2 may lead to pancreatic, melanoma and prostate cancer.
2) Lynch syndrome
This syndrome is a hereditary disorder caused by mutations in specific mismatch repair genes such as MLH1, MSH2, MSH6, PMS2, and EPCAM. An individual born with these mutated genes is at higher risk of developing colon cancer, endometrial cancer and other types of cancers such as brain, urinary tract, pancreas and stomach cancer.
3) Li-Fraumeni syndrome
It is a rare hereditary disorder caused due to the mutation in the TP53 gene. This mutation can increase your risk of developing soft tissue sarcomas, leukemia, breast cancer, lung cancer, brain tumors and adrenal gland cancer.
4) Cowden Syndrome
This syndrome is caused due to mutation in the PTEN gene. It puts a woman at the risk of developing breast, uterine and thyroid cancer whereas men are at a risk of developing thyroid cancer.
5) Familial Adenomatous Polyposis
It is also a rare hereditary condition caused due to a defect or mutation in the adenomatous polyposis coli (APC) gene. This mutant gene increases your risk of getting colorectal, soft tissue and brain tumors.
6) Von Hippel-Lindau Disease
It is a hereditary disorder which is associated with tumors arising in multiple organs. It occurs due to mutation in the VHL gene resulting in the abnormal growth of blood vessels and increased risk of developing kidney and other cancers.
7) Peutz-Jeghers Syndrome
It is also a rare disorder caused by mutation in the serine/threonine kinase 11 (STK11) gene. It can be characterized by presence of two or more hamartomatous polyps throughout the gastrointestinal tract, and mucocutaneous hyperpigmentation of the mouth, lips, nose, eyes, genitalia, or fingers. It increases the risk of breast, ovarian cancer, cervical, pancreatic, lung, gastric and colon cancer.
Reducing risk of hereditary cancer
Genetic testing is the first and most essential step to reduce the risk of hereditary cancer. This medical test will diagnose any unwanted changes in chromosomes, genes or DNA which are associated with the risk of cancer and other diseases. It is often recommended in patients who have a personal or family history of cancer.
Along with knowing your family history of cancer, you should also take other steps to lower the risk of developing cancer. It includes:
- Eating a healthy diet
- Exercising regularly
- Maintaining a healthy weight
- Having regular examination and checkups
- Beginning screening tests such as mammography and colonoscopy at an early age
- Quitting alcohol and smoking
- Reducing exposure to environmental carcinogens
Cancer is a disorder which is caused due to mutations in specific genes. An individual has 50% chances of getting a faulty or cancer causing genes from his/her parents. However, it is not mandatory that an individual with faulty genes will always develop cancer. Many others also can increase your risk of cancer such as exposure to environmental carcinogens, and certain chemicals from tobacco and smoking.
Knowing your family history can be beneficial for reducing the risk of developing hereditary cancers. Undergoing genetic testing and screening at an early age with a healthy lifestyle and regular health checkups will surely make dramatic changes and improve health outcomes of patients. So, be aware of past cancer diagnosis throughout your family tree and assess your possible risk of inherited cancer.
You can also explore, ‘Why is early detection essential for cancer prevention?’