Genetics of Breast CancerAutumn Gipson & Brianna Cantrell

Cancer Terminology

Type Of Cancer:

Location:

Carcinoma Epithelial Cells

Sarcoma Connective Tissue

Leukemia Circulatory / Lymphatic

Type of TumorsBenign tumours generally slow growing and enclosed in a fibrous capsule relatively harmless, although their location can make

them serious (such as a tumour located in the brain) not considered cancerous (they are not malignant) given names that usually end in "oma" (although

melanoma is a malignant skin cancer)Malignant tumours grow rapidly, invading neighbouring tissues can spread, to other sites of the body named using the type of tissue, cell type, and origin

Causes of Cancer Cancer can be caused by 3 factors:

› Gene Mutations Ex: mutations in BRCA1 &BRCA2 which can

lead to hereditary Breast & Ovarian Cancer› Environmental Factors

Ex: Tobacco, Radiation, Chemicals› Viruses

Ex: HPV – Cervical Cancer; Hepatitis B and C – linked to Liver Cancer

Types of Genes Which May Mutate to Cause Cancer:

Oncogene: a gene that, when mutated, disposes normal cells to change into cancerous tumor cells

DNA Repair Genes: DNA damages in frequently dividing cells are a prominent cause of cancer because mutations are more likely to occur

p53 Gene: if damaged or mutated, tumor suppression is severely reduced

Con’d. Tumor Suppressor Gene: a gene that

protects a cell from one step on to the path to cancer. When this gene is mutated, a loss or reduction in its function is caused, and the cell can progress to cancer

Breast Cancer Every woman has an 11% chance of

developing breast cancer during her lifetime

Most cases of breast cancer are sporadic; only 5-10% of all breast cancer cases are hereditary

Breast Cancer Cont’d.

The normal female breasts are paired structures that contain fat and glandular tissue designed to secrete milk. Cancer of the breast is one of the more common cancers in women. Risk factors: a family history of breast cancer, early age at first period, and late menopause.

Breast Cancer At Work….

The Result…

BRCA1 & BRCA2 Gene Are human genes belonging to a class

of genes known as tumor suppressors. These genes are linked to hereditary

breast and ovarian cancer The names BRCA1 and BRCA2 stand

for breast cancer susceptibility gene 1 and breast cancer susceptibility gene 2

BRCA1 Gene The BRCA1 gene, when properly

functioning, can help prevent breast cancer, but abnormal variations can significantly increase the risk of developing breast cancer. Females born with the affected gene face a 50-80 per cent risk of contacting breast cancer and a 40-60 per cent chance of developing ovarian cancer.

BRCA1

BRCA2 Gene There are more than 800 mutations in the BRCA2 gene

(Many associated with increased risk of breast cancer). Many BRCA2 mutations insert or delete a small

number of nucleotides in the gene, disrupting protein production

This results in an abnormally small, nonfunctional version of the BRCA2 protein.

Researchers believe that the defective BRCA2 protein is unable to help repair damaged DNA or fix mutations that occur in other genes. As these defects accumulate, they can allow cells to grow and divide uncontrollably and form a tumor.

Ovarian Cancer At Its Worst…

In Their Harmful State… Harmful BRCA1 mutations may also

increase a woman’s risk of developing cervical, uterine, pancreatic, and colon cancer.

Harmful BRCA2 mutations may additionally increase the risk of pancreatic cancer, stomach cancer, gallbladder and bile duct cancer, and melanoma.

Here’s Some Good News.. Even though these genes are genetic, not

every woman who are in a family known for breast cancer and/or ovarian cancer carries a harmful BRCA1 or BRCA2 mutation

Not all breast cancers are due to harmful mutated genes

Additionally, not every woman who has a harmful BRCA1 or BRCA2 mutation will develop breast and/or ovarian cancer.

It’s Not Only BRCA Genes.. Mutations in several other genes,

including TP53, PTEN, STK11/LKB1, CDH1, CHEK2, ATM, MLH1, and MSH2, have been associated with hereditary breast and/or ovarian tumors.

However, the majority of hereditary breast cancers can be accounted for by inherited mutations in BRCA1 and BRCA2

Current Solutions If At Risk…

Surveillance Prophylactic Surgery Chemoprevention

No Genetic Discrimination Allowed

Genetic discrimination occurs when people are treated differently by insurance companies or employers because they have a gene mutation that increases their risk of a disease, such as cancer.

However, in 2008, GINA was enacted to protect U.S. citizens against discrimination based on their genetic information in relation to health insurance and employment

The law does not cover life insurance, disability insurance, and long-term care insurance. In addition, the law does not cover members of the military.

Looking Ahead… Many research studies are being

conducted to find newer and better ways of detecting, treating, and preventing cancer in BRCA1 and BRCA2 mutation carriers. Additional studies are focused on improving genetic counseling methods and outcomes. Our knowledge in these areas is evolving rapidly