Dealing with breast cancer may involve genetic testing to determine suitable treatment options for patients. An assessment should be done by a specialist before any recommendation is made for each case.
Your gene, which is a section in your DNA inherited from either parent, carries information of a characteristic trait. When germline mutation happens, a change occurs in the gene that originated from germ cells (egg or sperm cells, or both) - the source of DNA for all cells in the body.
Around 5 to 10 per cent of breast cancers are hereditary cancers, which means cancer runs in the family and is associated with a change in genes such as BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two).
Dr Tira Tan, a consultant at National Cancer Centre Singapore's Division of Medical Oncology, explains what advanced breast cancer patients can expect if they inherit germline changes in BRCA genes.
Q: What does it mean if one inherits germline changes in BRCA?
They are at an increased risk of developing breast cancer. For example, the lifetime risk of BRCA1 carriers developing breast cancer at age 70 to 80 years old is 55 to 72 per cent, but only 7 to 8 per cent in the general population.
Doctors may recommend genetic testing if their patients are diagnosed with cancer at 45 years old or younger; suffer from multiple cancers; or have a strong family history of cancers such as breast, ovarian, prostate and pancreatic.
Q: What are the treatments for advanced breast cancer?
The mainstay is systemic therapy that targets the entire body. The choice of therapy depends on the subtype of breast cancer determined by examining the cancer cells for these markers: oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER 2).
For all subtypes of breast cancers, chemotherapy drugs may be included in the treatment plan at various points.
In general, ER-positive breast cancers are treated with hormonal therapy, often in combination with targeted therapies, while HER 2-positive breast cancers are treated by incorporating HER 2-directed targeted therapies.
About 40 per cent of triple negative breast cancer patients (with none of the three cancer markers) are eligible for treatment, which includes immunotherapy.
Knowledge of one's BRCA mutation status can help doctors identify treatments such as platinum chemotherapy or targeted therapies like PARP inhibitors. It can also benefit other family members who are at risk of the same hereditary condition.
Q: What are the options to manage the increased risk of breast cancer that is hereditary?
Adopt a healthy lifestyle and conduct regular breast self-exams. Individuals with increased risk can go for yearly breast screening through magnetic resonance imaging and mammograms, from as early as 25 years old.
There are medications to lower breast or ovarian cancer risk. Preventative surgery to remove breasts, or ovaries and fallopian tubes, can be considered. The latter may be suggested for BRCA1 or BRCA2 carriers who do not intend to have any more children.
Dr Tira Tan
Consultant, Division of Medical Oncology
National Cancer Centre Singapore