15-Issue 4 , 2015-Cover Story Precision in the Fight Against the Global Cancer Problem

Precision in medicine is a popular notion: precision to target an individual, precision to target a tumour, precision to target a molecule within a tumour. On occasion, this notion of precision no doubt evokes a crude analogy with images of the laser-guided missiles of war. As with modern warfare waged on any enemy, the war on cancer will use precision tools in order to win – such is the hope, which is not without reason given some notable successes. However, in both scenarios, the outcomes are not so precise; the reality is somewhat messier. Apart from the side effects (the collateral damage of powerful drugs), a patient developed cancer in the first place because of a specific set of exposures and circumstances and the outcome of treatment will be affected not just by their genome or that of their tumour, but also by their general health status, co-morbidities, lifestyle, as well as access to timely diagnosis, treatment and care, etc. Consequently cancer control must be considered broadly, embracing the sociopolitical as much as the molecular. In this wider context, if we do permit ourselves to submit for a moment to the legacy of U.S. President Nixon’s military terminology, what are our best available weapons to fight the war on cancer? Where precisely do we stand? Major investment and international cooperation succeeded in yielding the sequence of a typical human genome, emphasising a common heritage. This was followed by coordinated efforts to discover the genetic differences between individuals, revealed as variations in DNA sequence. Attention also turned to differences between the genomes of cancer and normal cells, with mutations revealing the genes and pathways most commonly altered in the progression from normalcy to malignancy. This backdrop of genetic information continues to provide remarkable insights into the previously hidden biology of cancer, opening the potential for drugs to target the molecular Achilles heel of a particular tumour type and to avoid both the worst of the side effects for the individual patient and crucial loss of time for those whose tumour is not susceptible to the drug concerned. Such is the cornerstone of precision medicine.