How has breast cancer treatment changed in 20 years of precision medicine?

2018 marks a milestone in precision medicine. It has been 20 years since Herceptin, the first targeted therapy for breast cancer, was approved by the FDA for use in the US. What has changed about diagnosis and treatment of breast cancer in that time, and has the prognosis improved?  

If a woman in the 1990s had a breast lump, typically, she would likely have had a FNA (fine needle aspiration) biopsy, then if the diagnosis was confirmed, there may have been surgery to remove the tumor, followed by chemotherapy and/or radiotherapy and possibly hormone treatment. Drugs were available, but they attacked good cells in the process of destroying the malignant cancer cells, leading to significant and debilitating side effects. The arrival of Herceptin changed the landscape as it was the first therapy designed to target a biomarker in the tumor itself.  

Herceptin (trastuzumab) is a monoclonal antibody for cancers that overexpress high amounts of the HER2 protein. HER2 makes cancer cells grow and divide, and Herceptin attaches to HER2 to stop this process. It was given to around 15-20 per cent of women whose aggressive HER2 positive cancer did not respond well to chemotherapy. Over the years the indications have changed and Herceptin, still a very important drug in an expanding selection of therapy choices, can now be given for early stage breast cancer, for metastatic cancer, or in combination with other drugs, and even as a standalone treatment without chemotherapy. 

An important factor for Herceptin, and the development of precision medicine, is that it has a companion diagnostic test which is used to identify high levels of HER2, which determines whether a patient will respond to the medicine or not. Targeted therapies that have joined Herceptin, such as Perjeta and Kadcyla, also have diagnostics to test for BRCA or high levels of HER2 protein expression to identify a patient’s suitability for the drug. 

Over these 20 years, there has also been more precise recognition of the genetics underlying breast cancer. The BRCA gene is linked to a higher risk of breast and ovarian cancer. Women with a family history of these diseases can be tested for the BRCA gene before any symptoms may develop. BRCA came to the fore when actor Angelina Jolie announced she was a carrier and elected to undergo preventative surgery. Knowing their genetic risk factors can raise women’s personal awareness of the disease and widen their options for future treatment. 

Perhaps one of the biggest changes over the time Herceptin has been available is the increase in public awareness of breast cancer. The disease is now very high profile and women are much more aware, not only of the treatment options available, but the importance of early detection. National screening programs are detecting irregularities at a stage when patients can benefit from much earlier treatment.  

The last 20 years have seen an unprecedented leap in advances for many cancers that would have been fatal or severely limited life expectancy just a few decades ago, but the next 20 could see an altogether different approach to fighting cancer. Immunotherapy, where the body’s immune system is manipulated or strengthened to fight disease, is advancing in oncology but is in early stages for breast cancer. Research into the role played by hormones has contributed to new drug development and could also help reduce the risk of getting breast cancer. There is likely to be progress in the use of vaccines to protect against or fight breast cancer, as seen with the HPV vaccine for cervical cancer. A breast cancer vaccine developed at Johns Hopkins Kimmel Cancer Center (US) is currently in trials. There is headway in nanotechnology, which enables precise imaging to locate a tumor and improve drug delivery. There are even experiments taking place using soundwaves to destroy cancer cells.  

Diaceutics is determined to ensure high-quality, actionable, diagnostic testing takes place much earlier in the patient journey. Breast cancer is a good example of how such testing, innovative treatments, screening and public awareness have all combined to raise survival rates and quality of lifeIn the US, 10-year survival increased from 78.7% (1990-1994) to 84.7% in 2004. Today, the NIH National Cancer Institute (US) puts 5-year survival at 89.7% (2007-2013, latest year for which stats are available)Breast cancer remains, however, the most common cancer for women, but thanks to targeted therapies such as Herceptin, better awareness and developments in precision medicine, the prognosis for many is much improved.  

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