Medical oncology

Traditional or standard chemotherapy works by disrupting the cell cycle. Each time a new cell forms it goes through a series of phases in order to become mature.  Traditional chemotherapy drugs target the different phases of the cell cycle. By disrupting or stopping a particular phase, a cancerous cell can no longer mature and divide and ultimately dies.

Some cancers make use of your body’s own hormones to grow and multiply.  These cancers are known as ‘hormone dependent’ cancers and include some types of breast, uterine and prostate cancers.  Hormone therapy uses drugs to block the body’s own hormones, e.g.  testosterone in men and oestrogen in women.  By stopping or lowering the amount of hormones the tumour receives, the growth of the cancer can be slowed.

Your immune system is designed to protect your body from threats such as infections, toxins and abnormal cell development (cancer).  Your immune system usually prevents cancers from occurring, but sometimes it is not strong enough to combat abnormal cell growth.  Immunotherapy drugs boost or improve how your own body’s immune system works to fight cancer.  Immunotherapy drugs work in different ways and include:

• Checkpoint inhibitors: These drugs take the ‘brakes’ off the immune system, which helps it to then recognise and attack cancer cells.  e.g. pembrolizumab, nivolumab, atezolizumab, durvalumab, ipilimumab.
• Chimeric antigen receptor (CAR) T-cell therapy: T-cells from a patient’s blood are mixed with a special virus that makes the T-cells learn how to attach to tumour cells.  These cells are then given back to the patient so they can find, attach to, and kill the cancer.
• Cytokines: Cytokines are small proteins that carry messages between cells.  They are used to stimulate the immune cells to attack cancer.  e.g. interferon and interleukin.
• Immunomodulators: Boost parts of the immune system to treat certain types of cancer. e.g. thalidomide, lenalidomide.
• Cancer vaccines: Vaccines are being researched and developed with the aim of preventing or treating cancer through an immune response.  Sipuleucel-T is a vaccine that has been approved for advanced prostate cancer.
• Oncolytic viruses:  Research into how viruses may be used to kill cancer is ongoing.  By modifying viruses in the laboratory, it is hoped that they will be able to target, infect and kill certain cancerous cells.

Targeted therapies do not work in the same way as traditional chemotherapy even though they are technically considered to be a form of chemotherapy. As the name suggests, targeted therapies work by finding a specific target on cancerous cells that they can attack or block to stop the cells from making new cancer cells.  If your cancer type is known to have a target, it will be tested at the time of your biopsy or surgery to see if the target is present.  Assuming it is, a targeted therapy may form part of your treatment plan. As these drugs have a targeted action to the cancer cell, the damage to normal cells is usually reduced, but this does not mean that targeted therapies are free of side-effects.

Some types of targeted therapies include but are not limited to:

• Angiogenesis inhibitors:  Block the formation of new blood vessels to the tumour so that the tumour is deprived of nutrients. e.g. bevacizumab.
• Monoclonal antibodies:  Deliver molecules to the target on the cancer cell which then interfere with the cell’s ability to signal and divide. e.g. trastuzumab, pertuzumab, cetuximab, alemtuzumab.
• Signal transduction inhibitors: Block the signals passed from one molecule to another inside a cell.  By blocking the signals, the cell cannot function properly and its ability to divide is affected.  e.g. lapatinib, gefitinib, erlotinib, sunitinib, sorafenib.