WILL WE EVER CURE CANCER?

One of the most pressing medical challenges facing the world's ageing population is the fight against cancer. But is this a battle that's winnable - and what technologies are being developed to wage the war?

- PROF SARAH ALLINSON

One in two of us will develop cancer in our lifetime. Thanks to advances in diagnosis and treatment, though, more people are surviving cancer than ever. Will this trend continue and how close are we to finding a cure? That upward survival trend is likely to continue. But finding a cure? That's not so easy to answer, for a simple reason: cancer isn't one single disease but a collection of more than 200, each with unique features. Yet every cancer consists of a mass of abnormal cells, all originating from a single mutated cell that began to divide uncontrollably.

Cell division one cell dividing to produce two new ones - is essential for growing and maintaining our bodies. Cells that have become worn out or damaged must be replaced. This process is tightly controlled, so that cells are produced only when needed, and in the exact numbers and locations required. Cancer cells evade those controls and divide chaotically, while also eluding the back-up systems that suppress growth and weed out abnormally behaving cells. The result is a tumour.

Cancer cells acquire these characteristics through gene mutations. One important group of genes comprises the proto-oncogenes, which mutate to continuously produce a signal telling cancer cells to divide, becoming oncogenes. Turning off that oncogenic signal stops cancer cells dividing and can even kill them. That's the principle underpinning the concept of targeted cancer therapies, a treatment approach in which much progress has been made.

Targeted cancer therapies are more effective and have fewer side effects than traditional treatments such as chemotherapy and radiotherapy, and have now been in use for almost 50 years. The first were hormone therapies used for diseases such as breast and prostate cancer, whose growth depends on the hormones oestrogen and testosterone, respectively.