Heredity and Cancer
Cancer, a deadly disease is abnormal multiplication of cells that invade other cells and tissues in an uncontrolled manner and spreads to other body parts through lymph systems and blood. Cancer is broadly categorized into groups such as carcinoma (occurs in skin or tissue), sarcoma (occurs in bone, cartilage and blood vessels), leukemia (occurs in bone marrow), myeloma and lymphoma (begins in cells of immune system) and also central nervous system cancers that occur in the tissues of the brain and spinal cord. They are categorized mainly on the basis of the point of origin or from the organ it begins to spread.
There exist many causes and risk factors associated with cancer beginning from consumption of tobacco to exposure to asbestos but it is the association of cancer and heredity that has gained significance in the field of continuous research apart from other linked areas of cancer such as its treatment, ways of prevention and of course how to recognize the warning signals. Cancer etiology is thus multifactorial with lifestyle, environmental, medical and genetic factors combine to form the malignancy.
What is hereditary cancer?
It is a subject of debate whether the inherited genes of an individual is a cause of developing cancer. When individual genes are predisposed to develop cancer, we refer to it as a hereditary cancer syndrome. Hereditary cancer is often described as an autosomal dominant trait, an alteration in gene leading to genetic susceptibility to development of cancer.
Why alteration in gene is a problem?
We have millions of cells in our body and as we grow, repair or age, the cells divide to form new cells, replace the damaged or the worn out cells by forming new cells. This happens through a process of encoding in the gene that consists of material called DNA. Each cell has two copies of each gene. The next generation inherits one copy of each gene from each parent. With cell division occurring, each gene is copied and given to the new cell. However, the problem arises when the inherited gene is copied with alteration of two or more genes. The mistake continues as the new cell begins its process of division resulting in mutation and the gene responsible for that is referred to as mutant gene. At the end, we might develop a large number of cells that consist of mutant genes. It has been found that the cancer-predisposing traits are mainly found in an autosomal dominant fashion and the susceptibility to cancer occurs as one inherits one copy of the altered gene. It is the genetic information of an individual that helps us to identify people who have greater risk of developing cancer.
Some features of hereditary cancer include:
- Tumors (multiple) in the same organ
- Primary tumors (multiple) in different organs
- Tumors with unique histology
- Tumors associated with congenital defects, cutaneous lesions, and genetic traits as well some other rare disease.
- Multiple tumors originating in an organ from one particular tumor.
Some of the hereditary cancer genes are:
- BRCA1 and BRCA2: Associated with Hereditary Breast Ovarian Cancer (HBOC)
- MSH2, MLH1 and MSH6: Associated with Hereditary Non-Polyposis Colorectal Cancer
- RB1: Associated with Retinoblastoma
- APC: Familial Adenomatous Polyposis
How to identify hereditary cancer?
It is mostly genetic testing that helps one to assess the hereditary cancer risk. The greatest benefit of genetic testing is that it helps the doctor make informed choices about health care such as risk-reducing surgical tactics and prevention medical options. Additionally, identification of gene mutations also helps other family members to determine whether they share hereditary cancer risks. Genetic testing is mostly done using blood.
What can an individual do if the person is at risk for hereditary cancer?
- First, it is important to undergo a cancer screening test
- Second, one can take recourse to prescription drugs to reduce the risk of getting the disease (For example, a woman who is susceptible to breast cancer should take tamoxifen).
- Third, one can speak to the doctors on the option of surgical removal of healthy tissue before it becomes cancerous. (If a woman has a risk of getting ovarian cancer might consult doctor and get removed the ovary and fallopian tube. In this way she reduces the risk of getting breast cancer too)
Additionally, one can take recourse to genetic counseling to understand the risk of hereditary cancer and be more psychologically stronger and better informed while taking a decision to fight this silent killer disease cancer.