jueves, 18 de octubre de 2018

Genetics of Breast Cancer

Download PDF Copy

By Yolanda Smith, B.Pharm.Reviewed by Susha Cheriyedath, M.Sc.

Breast cancer involves uncontrolled growth of cells in the breasts, which is caused by a mutation in genes.

These gene mutations may be inherited from the individual’s parents or acquired throughout their lifetime.

The cells in the body are continually being renewed through a process of cell replication and death.

DNA provides the specific information about the cells so that they can be replicated and continue to grow. If there is a small error in the DNA of the cell, that cell will continue to replicate the error further.

In many cases, a single error will not have a significant effect on the function of the cell, but with time successive errors may interfere with the growth or function of the cell, leading to abnormal behavior of the cell.

For example, cancer cells exhibit uncontrolled growth in the body as a result of the genetic mutation, which can take over the health tissue and cause significant health implications.

There are several specific genes that have been linked to an increased risk of developing breast cancer. They will be discussed in more detail below.

BRCA1 and BRCA2 Genes

The most common types of inherited breast cancer genes are BReast CAncer gene one (BRCA1) and BReast CAncer gene two (BRCA2).

All individuals have these genes, which are usually responsible to repair damage to cells in the breast and promote healthy growth of the cells.

However, if an individual has a mutation in one of these genes that interferes with its function, their risk of developing breast cancer significantly increases.

Approximately 1 in 10 of all cases of breast cancer may be attributed to an abnormality in the BRCA1 or BRCA2 genes.

Associated Risk of Breast Cancer

In the United States, each woman has approximately 12% risk of developing breast cancer in her lifetime. However, this risk increases dramatically up to 80% for women who have a mutation in the BRCA1 or BRCA2 gene.

Breast cancers linked to these gene abnormalities tend to present in women at a younger age and affect both sides of the body, in comparison to cases of breast cancer without the genetic mutation.

This increased risk of breast cancer for individuals with the gene mutation holds true for males.

Men with a mutation in the BRCA1 or BRCA2 gene have a risk of 8% of developing breast cancer by the age of 80, which is approximately 80 times higher than for males without the mutation.

The risk of related cancers, such as ovarian, colon, and pancreatic cancer also increases for women with a mutation in one of these genes.

Genetic Testing

There are several tests available to identify individuals who are at risk of developing breast cancer due to the presence of an abnormal gene linked to breast cancer.

These tests are not routinely recommended for the general population but may be offered to individuals who have been diagnosed with breast cancer or have a strong family history of the disease.

There are currently tests available for the following genes: BRCA1, BRCA2, ATM, CDH1, CHEK2, MRE11A, NBN, PALB2, PTEN, RAD50, RAD51C, and TP53.