Breast Cancer and Genetic Cancer Polyclinic

Breast cancer ranks first when evaluated in terms of incidence in women, and second after lung cancer when deaths caused by cancer are taken into consideration. 5% of the patients with breast cancer, which is seen in one in every 8 women, die.

Cancer Genetics

While the ancient Greeks thought that cancer depended on excess fluid in the body, in the 18th and 19th centuries, doctors thought that parasites caused cancer. Today, scientists have a lot of information about cancer and the relationship between genes. Ultraviolet, radiation, viruses and various chemicals cause damage to genes in the human body. If some specific genes (oncogens and tumour suppressor genes) are affected, the cancer develops.

Although many people have a family history of cancer, the majority of breast and ovarian cancers are not actually due to hereditary causes. Cancers that occur due to genetic differences that occur in the genetic structures of parents and are called ‘mutations’, which can be passed on to later generations, namely to their children, are called ‘hereditary cancers’. Approximately 10% of all cancers are inherited. It is important to know the genetic mutations that cause hereditary cancers in order to determine the risks related to cancer formation in the future. Therefore, it is possible to take precautions with early diagnosis and to prevent cancer and to increase survival in people at risk thanks to cancer screenings.

Mutations in the BRCA1 and BRCA2 genes are the most important cause of hereditary breast and ovarian cancers. Approximately 50-75% of these cancers are caused by mutations in these two genes.

A mutation associated with known genes has not been detected in many families with a history of breast and/or ovarian cancer. The reason for this is that familial cancers are caused by a combination of environmental factors such as mutations in other genes, common living space and lifestyle.

What is Your Risk for Breast and/or Ovarian Cancer?

Genetic risk assessment in hereditary breast and ovarian cancer can only be performed by physicians specialised in genetics.

A woman over 30 years of age with no family history of breast or ovarian cancer is in the average risk group.

For a person with a family history of breast or ovarian cancer, the BRCA1/2 genetic test is an appropriate test to evaluate the risk in terms of the formation and development of these two types of cancer.

If a person has already been diagnosed with breast or ovarian cancer, the BRCA1/2 genetic test is important to determine the prognosis of cancer and the likelihood of other types of cancer

Determining a person's cancer risk enables physicians to provide personalised advice through cancer screening and preventive methods.

What are the genes that may be related to cancer?

Tumour suppressor genes: These are protective genes. These genes normally limit the rate of cell division, repair damaged DNA, and control cell death. When these genes mutate, the cells continue to grow and eventually form a tumour. Nearly 30 tumour suppressor genes have been identified, including the BRCA1, BRCA2 (breast cancer), and p53 genes. In approximately 50% of all cancer cases, the p53 gene is either absent or damaged.

Oncogens: Genes that transform a healthy cell into a cancerous cell. HER2/neu (breast cancer) and Ras are the two most common oncogens.

DNA Repair Genes: Repairs errors that occur during the reproduction of DNA. Unrepaired errors lead to mutation and eventually cancer develops.

Cancer develops as a result of mutations in various genes, but most cancers are not associated with a particular type of gene. It causes cancer development by interacting with certain genes, other genes or environmental factors in unpredictable ways. Genes susceptible to some types of cancer have been identified, and most of these damaged genes have been found to cause cancer in certain organs. For example, BRCA1 and BRCA2 genes are involved in breast, ovarian and prostate cancers, APC, KRAS, MSH2 and MLH1 genes are involved in intestinal cancer, VHL gene is involved in von Hippel-Lindau syndrome, and STK11 gene is involved in Peutz-Jeggers syndrome. TP53 and RB1 are associated with many nonfamilial and spontaneous cancers.

What are the BRCA1 and BRCA2 Genes?

All humans have 2 copies of the BRCA1 and BRCA2 genes, one from the mother and the other from the father. The task of these two genes is to prevent the development of cancer in different parts of the body.

If the BRCA1/2 genes cannot function properly, the risk of developing breast, ovarian, pancreatic and prostate cancers increase.

In individuals with BRCA1/2 mutation, cancer occurs at an earlier age than other individuals, and there is a higher risk of secondary cancer in the same or a different organ.

Memorial Genetic Cancer Polyclinic, BRCA1/2 test enables the emergence of all hereditary genetic mutations that increase the risk of cancer by the analysis of these two genes.

Is BRCA1/2 Genetic Test Suitable for You?

By answering the following questions about personal or family history, it can be determined whether the genetic test is suitable for you:

• Has anyone been diagnosed with breast cancer before the age of 45?
• Is there anyone diagnosed with oestrogen receptor, progesterone receptor and HER2/neu negative breast cancer before the age of 60?
• Is there evidence of cancer in both breasts?
• Does anyone of any age have evidence of ovarian, ovarian canal, or primary peritoneal cancer?
• Is there a family member of any age with a history of male breast cancer?
• Is there a history of 2 or more breast/egg/pancreas and/or prostate cancer in the same family?
• Is there an individual in the family known to have BRCA1 or BRCA2 mutation?

Genetic Test Result Explanations:

A person undergoing genetic testing will obtain one of the 3 possible results: Positive, negative and insufficient result (Unassociated variant, VUs)

Medical Recommendations for a Person with a BRCA1/BRCA2 Mutation:

Medical Recommendations for Patients with No Detected Mutations

In patients with a history of breast cancer, care and clinical follow-up should be performed in accordance with the stage of the disease.

Patients with a family history of ovarian cancer:

Ovarian cancer screening and possible preventive surgical intervention should be discussed.

Patients with a family history of breast cancer:

Breast cancer screening and possible preventive surgical intervention should be discussed.

If there is a known BRCA1/2 mutation in the family and your test is negative, general breast cancer screening is more appropriate. If there are other types of cancer in the family, screening and preventive actions for those cancers should be evaluated.

Prepared by the Medical Editorial Board. Our health library contents have been prepared for informational purposes only and with the scientific content on the registration date. For all your questions, concerns, diagnosis or treatment about your health, please consult your doctor or health institution.