IS THERE A FUTURE FOR NATURALLY SOURCED BREAST CANCER TREATMENT?

Rebecca Im (OHS)

Breast cancer is the most common type of cancer in the UK, with 55,176 cases3 between 2015 and 2017 alone. It is caused by mutations in oncogenes or tumour suppressor genes (e.g. BRCA14, TP53), which can either be inherited genetically or acquired sporadically during the patient’s lifetime. They can cause uncontrolled cell growth in the milk ducts or glands5, and if undiscovered or untreated, can develop into tumours which may metastasize (spreading to other areas of the body) further. As such a common type of cancer, there are a plethora of treatments available that have significantly improved breast cancer patient care: surgery, chemotherapy, radiotherapy, endocrine therapy, targeted therapy. Despite this progress, advanced metastasized breast cancer still remains untreatable.

Historically in many cultures (e.g. Traditional Chinese Medicine), pharmacological agents sourced naturally have been used in cancer therapy. Returning to these elements to find new phytochemical compounds may provide new chemoprevention sources for the future. An example of a common anticancer agent is the naturally occurring Paclitaxel, originally isolated from the Pacific yew tree (Taxus brevifolia). Paclitaxel is known to inhibit spindle microtubule dynamics6, which results in the inhibition of mitosis (cell division) of cancer cells and ultimate apoptosis (cell death). Despite its success, especially in destroying metastatic breast cancer cells, this treatment also has some negative drawbacks. Its nonselective nature results in healthy tissue also being destroyed during this treatment. Furthermore, Paclitaxel must be used in a solution of Cremophor and dehydrated ethanol7; both of which have toxic effects on the body, which means patients cannot be administered high doses of this drug. It is also important to consider the impact of harvesting trees for medicine. As Paclitaxel is found in the bark of Pacific yew trees, each time the bark is harvested, that tree is killed8. The slow growing nature of trees further emphasizes this financial and ecological cost; supply could never meet demand without synthetic manufacturing. Today, after several years of research, a synthetic form of Paclitaxel has been developed – Taxol. If we take time into consideration, plants are a quicker alternative that could be used therapeutically in breast cancer. Screening of fractionated natural compounds has shown that Artemisia absinthium’s9 Artemisinin has anticancer effects on several breast cancer cell lines (e.g. HeLa). This composite inhibits cell growth; causes apoptosis; prevents cell migration and thus diminishes the risk of metastasis. Further research has illustrated that biological extracts from plants have better outcomes than when the compounds have been synthetically isolated10, suggesting that it is the synergy between plant components that inhibits cancer. Investigating the interactions between these different compounds is another way to develop targeted cancer drugs. To answer the question, there certainly seems to be a future for breast cancer treatment sourced naturally. However, instead of directly using compounds from trees and plants as medicine, we should understand what structure causes these components to have these anticancer effects and replicate them synthetically. Ideally, these medications would inhibit cells with mutated genes specific to breast cancer (eg. BRCA1).