Genetic testing for cancer

Genetic testing is usually associated with prenatal screening; however, it is important to understand that these tests can be undergone at almost all stages of life.

The link between genetics and cancer risk

Our body’s cells develop and divide in a constant cycle until our death. Normally, this development and destruction process remains balanced and perfect.

Developing cancer tissue can be caused by a genetic mutation that leads to abnormal cell division. This mutation allows cancer cells to bypass our body’s defense mechanisms.

In most cases, a great number of mutations are required for the affected tissue to develop cancer. The process in which cells develop cancer properties through mutations is known as “malignant transformation”.

Most mutations that lead to cancer occur randomly throughout a person’s life. However, in some cases, mutations are inherited from one’s parents. These mutations exist in all the body’s cells and increase the risk of developing various types of cancer.

There are around forty known hereditary cancer syndromes. Each syndrome increases the risk for developing certain types of cancer, that may develop at various ages and life stages.

Genetic counselling is an important step to understanding the kinds of tests that should be taken, especially in cases of a family history of cancer.

These genetic tests allow healthcare providers to detect a risk for developing cancer before the disease breaks out.


Ovarian cancer, breast cancer and BRCA mutations

Around 225,000 new cases of ovarian cancer are diagnosed annually. 5-15% of all ovarian cancer cases are a result of BRCA1 or BRCA2 gene mutations.

A variant in the BRCA1 gene creates an 80% chance of developing breast cancer. Women who discover they are at an increased risk for cancer may choose to undergo preventive (prophylactic) mastectomy or prophylactic ovary removal. Medical observation and monitoring of these diseases are also recommended in these cases.

In addition, researchers today are working to develop drugs that may help reduce the risk for developing ovarian and breast cancer in women with the specific gene variations.


Colorectal cancer – HNPCC

Colorectal cancer is among the three most common types of cancer, with almost 2 million new cases annually. Although around 90% of cases are sporadic, around 10% are linked to genetic disorders.

One of the deadliest and most common genetic disorders that increases the risk of developing colon cancer is HNPCC (hereditary nonpolyposis colon cancer). Carriers of this specific gene variant are at an increased risk of developing colorectal cancer – up to 82% higher than the risk in general population.

In addition to colorectal cancer, this disorder increases the risk of developing other types of cancer such as stomach, uterus, ovarian and urinary tract cancer.


Familial Adenomatous Polyposis (FAP)

Familial Adenomatous Polyposis, or FAP, does not directly cause cancer, but leads to the creation of thousands of polyps in the intestinal tract, including the large intestine (colon).

Though during their first stages these polyps are not considered dangerous, their multitude is considered precancerous. This disorder can be detected by a relatively simple genetic test, but if left untreated, it may lead to severe risks. Around 95% or FAP carriers will develop intestinal polyps. When untreated, 100% will develop colon cancer before age 50.

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