Personalised medicine and its impact on cancer care

Over time, cancer management has improved from the use of harsh treatments and diagnostic techniques to personalised care. Dr Allan Njau and Dr Jonathan Wawire, Molecular Pathologist and Anatomical Pathologist, respectively, at Aga Khan University Hospital, Nairobi explain how this transition has brought about revolutionary cancer treatment.

What are the traditional or conventional forms of cancer treatment?

They are three: Surgery, which involves total or partial removal of the cancer; chemotherapy, which typically involves a combination of drugs that kill the cancer cells usually given before and/or after surgery or even without surgery; and radiotherapy, a treatment that uses high-energy radiation to kill the cancer cells. The three methods are often combined. Healthy cells can become “collateral damage”,  where they are affected or killed while using chemotherapy and radiotherapy, therefore limiting the success of treatment.

Newer forms of cancer treatment are emerging, and some are already in use. What is personalised medicine in the context of cancer?

Personalised medicine or precision medicine involves formulating disease treatment or prevention plans while considering the differences in individuals, which is determined by their genes, lifestyles and the abnormal genes that initiate or drive cancer growth. The aim is to find the best available treatment at the right time for the right individual.

Is personalised medicine the same as targeted therapy?

Targeted therapy falls under personalised medicine. In targeted cancer therapy, uniquely designed drugs, hormones or antibodies block the genes or proteins “molecular targets” that drive cancer growth and spread.

Which cancer patients are eligible for targeted therapy?

Depending on the type of cancer, stage, recurrence status of cancer or failed standard “chemo” or “radio”- therapy, your oncologist may recommend molecular test(s) on the cancer tissue or blood to analyse the status of the “molecular targets” for which targeted therapy, hormones or drugs may be applied. We generally call these molecules or molecular targets, biomarkers.

The biomarkers can be prognostic, meaning that they are used to predict the biologic behaviour and aggressiveness of the cancer, or predictive, making them useful in predicting or identifying the therapy that would be best for that type of cancer.

Patients who cannot tolerate “chemo” or “radio” due to underlying conditions, side effects, or age, can benefit from personalised therapy.

Multiple other cancers including breast, lung, melanoma, pancreatic and renal cancer are amenable to targeted therapy. What about immunotherapy?

The body’s immune system is a powerful weapon to fight cancer. However, some cancer cells produce molecules that suppress the immune system. Testing for these immune suppressive molecules allows doctors to harness your own immune system to fight cancer by giving drugs that frustrate cancer cells. Again, pathology specialists do this testing with access to the right equipment. An example is the treatment of advanced oesophageal, gastric cancer and cancer of the cervix, which have a high prevalence in Kenya.

What other benefits does molecular testing confer other than treating patients?

The technique is useful for screening relatives of cancer patients in families with strong history of cancer. This facilitates early screening, diagnosis and treatment; increasing the chances for cure. An example is BRCA 1 and 2 gene testing for hereditary breast and ovarian cancer syndromes.

What are the challenges of targeted therapy in cancer?

Currently, targeted therapies are not widely accessible, and although the cost is dropping with the passage of time, they remain expensive. Patients can also suffer from various side effects although less severe than chemotherapy.

By Dr Allan Njau and Dr Jonathan Wawire