Quarter of skin cells ‘on road to cancer’

More than a quarter of a middle-aged person’s skin may have already made the first steps towards cancer, a study suggests. Analysis of samples from 55- to 73-year-olds found more than 100 DNA mutations linked to cancer in every 1 sq cm (0.1 sq in) of skin. The team, at the Sanger Institute, near Cambridge, said the results were “surprising”. Experts said prevention was the best defence against damage from the sun.

Skin cancer is one of the most common cancers. Ultraviolet-radiation from sunlight bombards our skin and transforms it from healthy to cancerous tissue. Seeds of cancer Many of the mutations that culminate in skin cancer are already known, but the team wanted to know when they first started to appear.

The researchers analysed excess skin that had been removed from the eyelids of four patients. They then drilled down deeply into the skin’s DNA to discover the very first steps being taken on the journey to cancer. Dr Peter Campbell, the head of cancer genetics at Sanger, told the BBC News website: “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.” However, it would take multiple mutations – nobody is sure exactly how many – to culminate in a tumour. Source: Quarter of skin cells ‘on road to cancer’

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One Response to Quarter of skin cells ‘on road to cancer’

  1. Phil Krause says:

    It’s probably more surprising that we don’t have more skin cancer than we do. Our cells are constantly under attack from environmental processes. One of the worst forms of attack is sunlight. Luckily, most of the highest energy particles from the sun that have the highest frequencies are filtered out by the ozone layer, magnetic field and atmosphere. Our skin cells are the first to encounter the ones that do get through and they are subject to damage from these. Surprisingly, between 10,000 and 1,000,000 molecular lesions per cell per day are caused from direct sunlight. Considering that we have trillions of cells in our bodies, this is a tremendous amount of damage that could cause problems. Fortunately, our bodies have many very good repair systems that manage to repair most of these lesions. If our DNA inside our cells is damaged and is not repaired before the cell splits then the damaged DNA will be copied to the new cell. When those two cells divide into four cells the damaged DNA is copied again etc. All cancer cells have damaged DNA which divide without control; some of which become less sticky and are more likely to flake off into the lymph or blood systems and could metastasize somewhere else in the body.
    Our repair systems are unbelievably efficient and catch almost all of the damaged DNA. As we get older, these repair systems become less efficient and the damaged DNA builds up in our cells. One of the last in line defenses, is that if the DNA is not repaired, the cell is programmed to kill itself (apoptosis) to prevent the damaged DNA from replicating. As we get even older, our repair defenses fail one by one and the chances of a tumor increases exponentially.
    The surprising thing to me is how incredible our defense systems are in preventing most cancers before we have chance to create offspring. There is very little that Darwinian evolution can do to prevent the damage after we have finished reproducing. As the average age that western populations live to increases, so does the cancer rate. I have no doubt that science will eventually drastically reduce the effects of cancer.

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