A quarter of skin cells turning cancerous

Over a quarter of a middle-aged person’s skin cells may have taken the first step to becoming cancerous, according to a study published in the journal Science this month.

The findings are the result of research by a team at the Sanger Institute, near Cambridge, which was based on analysis of samples from the eyelids of four 55- to 73-year-olds. The study found more than 100 DNA mutations linked to cancer in every 1 sq cm (0.1 sq in) of skin – a far greater proportion than anticipated.

 In an interview for BBC Health, Dr Peter Campbell, the head of cancer genetics at Sanger, said: "The most surprising thing is just the scale. That a quarter to a third of cells had these cancerous mutations is way higher than we'd expect, but these cells are functioning normally."

UV radiation from the sun can trigger such mutation in skin cells, ultimately turning normal, healthy skin into cancerous tissue. The journey is a complex one, however, with mutliple mutations being required before skin damage results in a tumour. This process is still not fully understood, and the Sanger team had undertaken their research to determine just how early such mutations appear.

The results also showed that there were already anomalies in the way mildly mutated cells were behaving – such as exhibiting accelerated rates of growth – even though they were not yet a threat to health. Dr Campbell commented: "It drives home the message that these mutations accumulate throughout life, and the best prevention is a lifetime of attention to the damage from sun exposure."

The new research may also be of key significance to those developing new cancer drugs. These drugs often target such anomalies in cells, which could mean they are attacking a far higher number of non-cancerous cells than previously thought. "A treatment that kills 20-30% of normal cells would potentially be a lot of collateral damage," Dr Campbell said.

Per Hall, Clinical Director at Check4Cancer and a pioneer in the early detection of melanoma, comments: “This new research shows that the change from healthy skin to tumour is a long, cumulative process which may start many years – even decades – before tumours develop. Sun exposure habits play a vital role in limiting risk, and we now know that sunburn in adolescence can carry an 80% increase in melanoma risk. According to Cancer Research UK, getting sunburnt just once every two years can triple your risk of developing malignant melanoma. Even reddening of the skin is a sign of damage.

“In spite of this, a recent survey of over a thousand people carried out by the British Association of Dermatologists revealed that 96% of us fail to check our skin the recommended once a month for skin cancer, and more than 77% would not recognise signs of the disease. More worrying still is the fact that 72% of people admitted they had been sunburned in the last year. We need to start taking the warnings of research such as this seriously, and regulate our own sun exposure – and that of our children – from the earliest possible age.”