There are a number of genes that can cause a person to develop breast cancer. Some of these genes are inheritable, meaning they pass from parent to child. However, having the gene for breast cancer does not always mean a person develops it.

This article will go into detail about the role of genetics in breast cancer, whether breast cancer can skip a generation, and the next steps for a person who has a breast cancer gene.

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The American Cancer Society (ACS) notes that inherited genetic factors do not cause the majority of breast cancers. However, there are certain inherited genes that increase a person’s chances of developing breast cancer.

A gene is a sequence of DNA that determines certain traits, such as eye or hair color. Genes are transmitted in pairs from biological parents to their child. A child inherits one copy from each parent. Sometimes, a child can inherit a gene with mutations, which means that the gene does not function correctly.

Approximately 5–10% of breast cancer cases in people are hereditary.

Learn more about breast cancer genes here.

Other forms of breast cancer can occur due to gradual changes in a person’s DNA.

These forms of breast cancer, known as somatic mutations, are not due to inherited factors. Somatic mutations occur for a variety of reasons, such as aging or exposure to certain chemicals.

Inherited breast cancer genes cannot skip a generation.

If a person has inherited a gene that causes breast cancer, they have a 50% chance of passing it on to their children. If a person’s child does not inherit the mutated gene, the child cannot then pass it on to their future children.

However, while genes cannot skip a generation, the cancer can. Having a mutated gene is not a guarantee that a person will have breast cancer.

A mutated gene is still inheritable, even if the person does not develop breast cancer. This means that a person’s child may inherit the mutated gene from them and could develop breast cancer.

There are various inherited gene mutations that can cause a person to develop breast cancer. The most common causes of inherited breast cancer are mutations in the genes BRCA1 and BRCA2.

The BRCA genes are responsible for repairing damage to cells in a person’s body. These genes also help certain cells, such as breast or ovarian cells, to grow as expected.

When mutations occur in these genes, it can lead to atypical cell growth. Atypical cell growth can lead to the development of cancer.

If a female inherits a harmful BRCA gene, their risk of developing breast cancer by age 70–80 is between 45–69%.

Additionally, the ACS notes that males with the BRCA2 gene have a lifetime risk of 6 in 100 for developing breast cancer. Those with the BRCA1 gene have a lifetime risk of 1 in 100.

However, while there has been extensive research on the risk of breast cancer in females with the BRCA1 and BRCA2 genes, there has been less research on the cancer risk in males. As a result, these statistics might not be a true reflection.

Learn more about the BRCA gene here.

The ACS notes that most females who have breast cancer have no family history of the condition. However, having a family history of breast cancer can increase a person’s chances of developing it.

A female’s chances of developing breast cancer double if they have a first degree relative with the condition. A first degree relative is an immediate family member, such as a sister, mother, or daughter.

Breastcancer.org states that a female has a higher risk of inheriting a genetic mutation linked to breast cancer if they have:

  • a blood relative who developed breast cancer before the age of 50
  • a side of their family that has a history of breast or ovarian cancer
  • a relative with triple-negative breast cancer
  • other cancers as well as breast cancer in their family, such as colon, prostate, or stomach cancer
  • females in their family who had cancer in both breasts
  • Ashkenazi Jewish heritage
  • a male relative who had breast cancer
  • a known atypical breast cancer gene in their family

The risk of a person developing breast cancer increases with each additional family member who has it. Additionally, having a male relative who has breast cancer also increases a female’s chances of having it.

More research is necessary to determine the effects of family history on a male’s chances of developing breast cancer.

If a person is concerned that they may have inherited a breast cancer gene, they should speak with a doctor. A doctor may suggest for a person to undergo genetic counseling.

Genetic counseling involves a person speaking with a genetic counselor about their chances of developing breast cancer. Genetic counselors can also provide a person with resources and support.

This type of counseling can also help a person decide if they would like to take part in genetic testing or not. Genetic testing involves checking a person’s genetic profile for breast cancer-causing genes.

Genetic testing for cancer usually involves a person submitting a blood sample. However, other forms of genetic testing can use cell samples from a person’s:

  • hair
  • inner cheek using a swab
  • urine
  • amniotic fluid, which is the fluid that surrounds a fetus during pregnancy

If a person knows they have a BRCA gene, there are various medical options available to them.

These options include the following:

Frequent screenings

Breastcancer.org suggests that a person with a high risk of developing breast cancer may benefit from having more frequent screenings.

A person can speak with a doctor about how often they should get screened for breast cancer.

This can involve:

  • screenings before the age of 40
  • a monthly self-exam
  • a yearly, or twice yearly, breast exam
  • a breast ultrasound
  • a yearly digital mammogram, starting from age 30 or younger
  • a yearly MRI scan from age 30 or younger

Risk-reduction therapy

There are certain medications that can help reduce a person’s chances of developing hormone receptor-positive breast cancer.

Hormone receptor-positive breast cancers contain hormone receptors that are activated by certain hormones. When these hormones bind to the hormone receptors, they can stimulate growth in the cancer.

Hormonal therapy medications reduce the amount of these hormones in a person’s body.

These medications include:

Risk-reduction surgery

A person may choose to have risk-reduction surgery if they have a high risk of developing breast cancer.

According to the National Cancer Institute, risk-reduction surgery for breast cancer can involve removing one or both breasts, ovaries, or both pairs. There are two types of risk-reducing surgeries: bilateral prophylactic mastectomy and salpingo-oophorectomy.

Bilateral prophylactic mastectomies involve removing both breasts, including a person’s nipples, which is known as a total mastectomy. The other option is a subcutaneous mastectomy, which involves removing as much breast tissue as possible while leaving a person’s nipples intact.

A total mastectomy reduces a person’s risk of developing breast cancer better than a subcutaneous mastectomy.

A salpingo-oophorectomy involves the removal of a person’s ovaries and fallopian tubes. Removing the ovaries reduces the amount of estrogen in someone’s body, which can slow the growth of some breast cancers. Estrogen can promote the growth of some types of breast cancer.

For people with a mutation in the BRCA1 and BRCA2 genes, a bilateral prophylactic mastectomy can reduce the risk of breast cancer by at least 95%.

It can also reduce the risk of breast cancer in people with a strong family history of this condition by up to 90%.

A salpingo-oophorectomy can reduce the chances of breast cancer in people with a high risk by 50%.

For people with mutated BRCA genes, premenopausal removal of their ovaries and fallopian tubes can reduce breast cancer risk by 50% and ovarian cancer risk by 85–95%.

Ovary removal may also increase a person’s chances of survival if they do develop breast cancer due to mutated BRCA genes.

Inherited genetic factors may cause a person to develop breast cancer. However, a person who inherits a breast cancer gene may not always develop cancer.

This means that a breast cancer gene can appear to skip a generation, even though it does not.

If a person has a family history of breast cancer, they are at a higher risk of developing it. A person can speak with a doctor about their risk of breast cancer to see if they may qualify for or benefit from genetic counseling.

A person can then decide if they would like to have genetic testing.

If a person has a mutated BRCA gene, there are various medical options available to them. A person should speak with a doctor about which option is right for them.