Cancer Genetics and Family History 

Breast Cancer is the commonest type of cancer in women worldwide, but is not just one disease, on the contrary, it’s a heterogeneous spectrum based on a combination of receptors on the surface of the cancer cells. Receptors include: Oestrogen receptor (ER), Progesterone receptor (PR) and Human epidermal receptor 2 (Her2). Based on these receptors expression, Breast Cancers are typically divided into 3 main types: 1) ER+ Breast Cancer, 2) Her2+ Breast Cancer and 3) Triple Negative Breast cancer (TNBC where none of the 3 receptors are expressed). These subtypes unfortunately behave in completely different ways. Their biology is different, their prognosis is different and the treatment is also fundamentally different. 
Some cancers can develop due to “a way of life”. It is fair to say that obesity is a risk factor for ER positive breast cancer and smoking is a risk factor for triple negative breast cancer. Despite this however, most women diagnosed with breast cancer do not smoke, do not drink, they are not overweight and the cancer seems to happen by chance. Most breast cancers will therefore develop sporadically, but in around 20% of patients of TNBC and up to 10% of ER+ breast cancer, a genetic mutation will be the cause of the cancer and there are things we can do now to mitigate this risk. BRCA1, BRCA2, PALB2, TP53 and PTEN mutations are the main mutations behind “genetic breast cancers”. 
Genetic mutation carriers (men and women) will have a higher risk of developing breast, ovarian, prostate, pancreatic and cholangiocarcinoma (in that frequency) throughout their lives. It is important to stress that carrying a genetic mutation does not mean that person will develop cancer, but the risk is higher no doubt. Enhanced (more intense) screening for cancer therefore needs to be carried out, but since cancer screening is not 100% accurate, careful consideration of risk reducing surgery such as mastectomies (removal of the breasts) and bilateral oophorectomy (removal of the ovaries) can also be considered, but not mandatory or necessarily indicated. Once a genetic mutation has been identified, the whole family (ideally) needs to be screened at some point to assess where the mutation came from and who else in the family has it. These mutations are autosomal dominant, which means there is a 50% chance of passing it on to the next generation (boys and girls). 

NHS Trusts will typically offer genetic testing to any person with either: 

Any type of Breast Cancer under the age of 40. 
Triple Negative Breast Cancer under the age of 60. 
Men of any age with any type of Breast Cancer. 
Women by bilateral Breast Cancers under the age of 60. 
Woman with both Breast and Ovarian Cancer. 
Strong family history of Breast and Ovarian cancer. 
Get in touch with Dr Hugo to learn more. 
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