So far, gathered from the latest data as collected and assimilated by World Health Organization (WHO) it is revealed that during 2015, cancer was the cause of death of 8.8 million people across the world. Nearly 1 in 6 deaths was due to cancer. The number of new cancer cases expected to rise to 22 million within the next two decades. There are a lot of researches around the fact of family history of cancer. You may be interested to know what cancers are genetic.
Family History of Cancer
It is deduced by researchers that, some of the cancers are directly linked to defective (mutant) genes. Approximately 14 of defective genes have already been identified by the researchers those are mutating and directly responsible for causing genetic cancers. These genes are inherited from the person’s parents. It is believed that more or less 5-10% of cancer cases are genetic or hereditary.
Summarily, if there is a prolonged family history of any particular type of cancer reoccurring through generations, it can be called genetic cancers and could be inherited by further generations. Hence, the family history of cancer is important and may often be related. But cancer is not directly inherited but the defective genes make it more likely for that particular cancers to occur.
On the other hand, cancers that are not due to inherited gene/s but malignant changes (mutation) occur is called sporadic cancer. Therefore, it could be concluded; all cancers are caused by genetic mutations, but not all genetic mutations are inherited.
Which Cancers are Genetic?
People commonly wonder which cancers are genetic. As of now, some of the cancers are better identified as genetic cancer, although these cancers can occur as sporadically too. This needs to take into consideration, the family history of cancer and perform necessary tests. It is important to perform special tests in family members, to infer if they have the gene of interest or not.
Here are some instances of cancers commonly found as genetic cancer:
- Bone cancer (osteosarcoma)
- Soft-tissue sarcoma
- Acute leukemia
- Breast cancer
- Brain cancer
- Prostate cancer
- Adrenal cortical tumors (Kidney Cancer)
Note: Stomach, colon, pancreas, esophagus, lung, and gonadal germ cells (sex organs) cancers in some cases have been reported also for genetic cancers.
What is Genetic Cancer?
It is now a known fact that cancer is caused by abnormal mutation of genes and these changes occur intermittently in one or a few cells. This is one of the main reasons why family history of cancer is always important in evaluating a case. It is natural consequences of that cell/s getting damaged on various grounds. These changes in genes is acquired or somatic.
But when the abnormal DNA is passed from the Parent(s) to their offspring/s it is called genetic. This abnormal, mutated or damaged DNA/s damaged DNA/s is/are present in the egg or sperm. After fertilization of the egg the single cell zygote forms. That zygote starts to divide itself to form the fetus. Since all the cells in the baby (fetus) come from that zygote the abnormal, mutated or damaged DNA/s is/are carried over on to the next generation and so on.
It is highlighted here that, people those are carried over with such mutated bad genes do not necessarily suffer from cancer, but their risk of developing the disease at some point during their lifetime is higher than average.
Syndromes of Genetic Cancers:
Cancer in parent (s), close relatives at each side of the family separately or sibling, should be more cause for concern to detect whether it is genetic or acquired. Certain things should be existing in family history that could be concluded as family cancer syndrome after due genetic test, such as:
- Many cases of an uncommon or rare type of cancer (like kidney cancer).
- Cancers occurring at younger ages than usual (like colon cancer in a 20 year old)
- More than one type of cancer in a single person (like a woman with both breast and ovarian cancer)
- Cancers occurring in both of a pair of organs (both eyes, both kidneys, both breasts)
- More than one childhood cancer in a set of siblings (like sarcoma in both a brother and a sister)
Genes Related to Genetic Cancers at a Glance:
Which cancers are genetic, may be related to some of these examples.
Genes: BRCA1, BRC BRCA1 and BRCA2
- These genes are tumor suppressor genes; their protein products are responsible for preventing uncontrolled cell division.
- Related cancer types: Female breast and ovarian cancers, and other cancers, including prostate, pancreatic, and male breast cancer
- The TP53 gene (also known as p53) codes for a very important tumour suppressor protein. It is involved in many activities that prevent cells from dividing uncontrollably
- Related cancer types: Breast cancer, soft tissue sarcoma, osteosarcoma (bone cancer), leukemia, brain tumors, adrenocortical carcinoma (cancer of the adrenal glands), and other cancers.
- PTEN is also a tumor suppressor gene. Like TP53, if PTEN is defective, cells may continue dividing, even though cancer-causing changes may be present.
- Related cancer types: Breast, thyroid, endometrial (uterine lining), and other cancers
Genes: MSH2, MLH1, MSH6, PMS2, EPCAM
- The genes involved in mismatch repair genes. The proteins encoded by these genes are responsible for correcting mistakes made during DNA is copied (DNA replication).
- Related cancer types: Colorectal, endometrial, ovarian, renal pelvis, pancreatic, small intestine, liver and biliary tract, stomach, brain, and breast cancers
Gene: APC (adenomatous polyposis coli)
- APC is a tumor suppressor gene that controls how often a cell divides, how cells stick to each other, and DNA damage detection
- Related cancer types: Colorectal cancer, tumors in the small intestine, brain, stomach, bone, skin, and other tissues. Also associated with non-cancerous (benign) growths (polyps) of the colon and small intestine.
Gene: RB1 (retinoblastoma)
- The RB1 gene codes for the Rb protein, which is a tumor suppressor. Rb is responsible for halting cell division if conditions are not optimal. It has roles in controlling other proteins involved in DNA replication, apoptosis, and cell maturation.
- Related cancer types: Eye cancer (cancer of the retina), pinealoma (cancer of the pineal gland), osteosarcoma, melanoma, and soft tissue sarcoma
- MEN1 codes for a tumor suppressor protein called menin. The function of menin is appears to be involved in regulating cell division, DNA repair, and apoptosis. More researches are there to be sure.
- Related cancer types: Pancreatic endocrine tumors and (usually benign) parathyroid and pituitary gland tumors
- The RET gene is a proto-oncogene that is involved in cell signaling. It spans the cell membrane, and acts as a receptor for signals that help cells respond to changes in their environment.
- Related cancer types: Medullary thyroid cancer and pheochromocytoma (benign adrenal gland tumor)
- The VHL gene works indirectly coordinate the body’s response to changes in oxygen levels by controlling cell division, and the formation of new blood vessels and red blood cells.
- Related cancer types: Kidney cancer and multiple noncancerous tumors, including pheochromocytoma.