I have been running mock interviews on behalf of Oxbridge Applications for many years now and during that time, the answer to one of my favourite questions to ask medics-to-be has changed. My original question was “Tell me the different ways you can treat cancer”. In response to this rather broad question typically came a response listing three approaches; the first and most straight-forward being the surgical option, where the tumor is physically cut out of the body. While effective, this approach is quite blunt, and even if a few cancer cells remain, the disease will eventually return. In addition, this approach is useless against “liquid” or haematological cancers, such as leukemia.
The second approach is that of chemotherapy, where cyto-toxic drugs are introduced into the body. Cancer cells are characterized by their extremely rapid growth rates, and in its simplest form, chemotherapy involves the introduction of drugs into the body that are toxic to all human cells, but particularly to those with the fastest growth rates of cell division. Using this approach, the fast-growing cancer cells are hopefully eliminated, but in the process so are other non-cancerous but fast growing cells in our body, such as the hair-follicles in our epidermis and the rapidly-dividing cells of intestinal lining, thus explaining why chemo patients lose their hair and experience gastro-intestinal distress during treatment.
The third approach is radiotherapy, or the use of radiation to destroy cancerous cells. It is somewhat ironic that radiation can not only cause cancer but cure it, but even when being used by medical professionals, radiation therapy must be very carefully applied in order to minimize the damage to surrounding cells and tissue. During radiotherapy, very precise beams of radiation are used, originating from multiple different origins or lasers. The idea is that each ‘beam’ in itself is too weak to cause significant damage to the tissue that it passes through en route to the tumor, but at the point where all the beams intersect (i.e. at the tumour site), the intensity of the radiation is high enough to ablate any cells present. While very effective on some tumor types such as prostate, like the surgical approach, radiotherapy is not effective against haematological cancers.
However, in recent years, new treatment approaches have become available which have dramatically improved the outcomes of patients with previously few treatment options. The first example has been the arrival of targeted therapies. These differ from chemotherapies in that these drugs target specific receptors or pathways in order to halt or reverse tumor progression. As the drug’s have a more specific mechanism of action, they tend to be more effective than chemotherapy for specific types of tumors, and usually with few side effects as well. A famous class of targeted therapies is the TKI inhibitors for treatment of Chronic Myeloid Leukemia (CML). This interesting article from the Blood Cancer Journal details some history on how dramatically TKI inhibitors improved the prognoses for patients with CML, as well as provide insights into how patients who do not respond to TKIs can be treated.
Finally, but by no means least, has been the advent of immunotherapies for the treatment of cancers. Broadly speaking, this newest class of therapies works by priming our immune system, prompting it to better identify malignant cells in our body and then destroy them. While the concept has long been discussed, it has taken researchers decades to find the right ways to stimulate the immune system without over-loading it and causing potentially fatal adverse events. For an interesting presentation on immuno-oncology, follow this link.
For those of you more focused on natural sciences and biology, I urge you to read up and dig deeper into the immunology and biochemistry behind some of these new therapies. For you medics, take time to consider all the different treatments options facing patients and how these vary depending on the patient as well as tumor type. A good exercise would be to chose two different tumor types, such as breast and multiple myeloma, and do some research online to see how different the treatment approaches are for these cancers.