Breast cancer can develop in the cells of the lobules or the ducts but more uncommonly, it can begin in the stromal tissues, the fatty and fibrous connective tissues of the breasts. It is considered one of the most common cancers affecting women and recent reports indicate over 2 million new cases in 2018. Despite the effort to educate the public by raising awareness, according to the Breast Cancer Research Foundation, since 2008, the incidence of breast cancer has increased by more than 20%. The survival rates vary greatly internationally ranging from 80% or more in countries like Sweden, Japan and North America to below 40% in the low-income countries.
The survival rates are also considered low in developed countries primarily because of the lacking early detection programs and the high number of women presenting late-stage of the disease. Although genetics can also influence the development of the disease, other factors such as changes to lifestyle habits could help reduce the chance of developing breast cancer. In recent years, the scientific advances have delivered an overwhelming number of choices as treatment options for different cases ranging from surgery, radiation, chemotherapy, immunotherapy and hormonal (anti-estrogen) therapy. However, the research still continues to find the novel approaches to fight the different types of breast cancer and ultimately even hopes of developing a vaccine that can help eradicate this global burden.
Genetic Mutation and Tumor Cell
Although lifestyle factors such as lack of exercise, alcohol intake, smoking are associated with an increased risk of developing breast cancer, the inherited faulty gene is responsible for around 5% of the cases. For instance, the inherited mutation in the genes BRCA1 and BRCA2 contribute to the development of breast cancer. The genes BRCA1 or BRCA2 are responsible for the production of tumor suppressors which prevents the cells from growing and dividing in an uncontrolled manner. This genetic mutation impairs DNA repair thereby enabling damaging mutations to persist in DNA which can result in the uncontrolled proliferation of cells resulting in the tumor.
Chemotherapy plus endocrine therapy was considered the standard treatment for early stage, hormone-positive breast cancer which had shown to lower the rate of recurrence by 30 years. Recently, a groundbreaking TAILORx study was conducted in a largest trial involving 10,000 patients enrolling 6 countries. The study was supported by the Breast Cancer Research Foundation (BCRF) which actually indicates that many women with early-stage breast cancer can actually avoid chemotherapy. Oncotype Dx is a prognostic assay used to measure the level of 21 genes in the tumor biopsy which can determine the risk of recurrence among the newly diagnosed women with early stage, hormone receptor breast cancer. The indicator shows a score from 1 -100 which is used to guide treatment and helps determine if chemotherapy should be used to prevent recurrence.
Novel approaches changing the outlook for breast cancer
Breast cancers are normally divided into HER2-Positive, hormone receptor-positive and triple-negative disease and there are various drugs focusing on targeting breast cancer groups. One of the challenges of the breast cancer treatment is the selection of the appropriate treatment for the right patient as research indicates that the genetic makeup of the tumor determines how each woman respond to various treatments. Therefore, a better understanding of why some patients respond well to certain breast cancer treatments while others don’t is essential to improving their lives.
- Aromatase inhibitors verses Tamoxifen in early breast cancer: In order to determine the optimal way of using aromatase inhibitors or tamoxifen as endocrine treatment for those with early breast cancer, a meta-analysis of individual data of 31920 postmenopausal women was conducted. The study was published in The Lancet titled ‘Aromatase inhibitors verses tamoxifen in early breast cancer: patient-level meta-analysis of the randomized trials’, which shows that aromatase inhibitors can lower the rates of recurrence by about 30% when compared with tamoxifen. The 5 years of an aromatase inhibitor lowers the 10-year breast cancer mortality rates by about 15% compared with 5 years of tamoxifen.
- CDK4/6 for advanced ER-positive breast cancer: Cyclin dependent kinsases (CDK) is responsible for regulating the process of cellular division. If CDKs can be blocked, cell multiplication would not be possible thereby slowing or even stopping cancer. Although previous trials have blocked all the different types of CDKs, the new drugs only block the CDK4 and CDK6 which is more effective. The clinical trials have resulted in the approval of two CDK4/6 inhibitors; palbociclib which was approved in 2016, ribociclib approved in 2017 and a third drug abemaciclib which could be approved for 2018. Each of the drugs shows promising results for women with hormone receptor-positive metastatic breast cancer although more studies are required on the use of CDK4/6 inhibitors.
- Immunotherapy and triple negative breast cancer (TNBC): TNBC is considered one of the most complicated forms of breast cancer to treat with lower survival rates than any of the other forms of breast cancer. According to a study presented at the European Society for Medical Oncology 2018 Congress, combining chemotherapy with immunotherapy could improve survival for women with triple-negative breast cancer. For those with programmed death ligand 1 (PD-L1)-Positive tumors, the combination of atezolizumab with nab-paclitaxel showed improved progression-free survival (PFS). However, the trials are ongoing to understand the best chemotherapy backbone to pair with immunotherapy.
Breast Cancer Vaccine in the Future?
A research conducted by National Breast Cancer Foundation (NBCF) potentially holds the key for future breast cancer vaccine. Dr Kara Britt from the Peter MacCallum Cancer Center in Melbourne is studying the reason why childbearing can lower the risk of a woman developing breast cancer, particularly early childbearing. The study could unveil the biological reasons for this decreased risk factor which may potentially result in breast cancer vaccine. In a statement, Dr. Britt explains, “I’m trying to define which cell is involved in breast cancer protection and then we’ll know which cell to target for the treatments.” In theory, the vaccine could mimic the hormonal changes of a young woman during pregnancy which could help lower the risk of developing breast cancer.