if our skin cells are constantly dying and being replaced by new ones, how can a bad sunburn turn into cancer YEARS down the line?

Question

if our skin cells are constantly dying and being replaced by new ones, how can a bad sunburn turn into cancer YEARS down the line?

In: 3306

Answer 1

A game of cellular cat and mouse:
Our cells come with inbuilt safety systems that can stop cancer developing.

Some of these systems stop our precious DNA from becoming damaged in the first place. For example, the sun’s UV rays can cause a build-up of oxygen-containing molecules inside cells that can damage DNA. This is why our cells make antioxidants to mop them up.

But even with this safety system in place, genetic mistakes can still crop up and, in fact, do so relatively regularly. After all, each time a cell divides it copies the 3 billion DNA ‘letters’ that make up its genetic code – a mammoth task to do error-free. And if a cell is exposed to lots of a cancer-causing substance, such as tobacco smoke, then its defences can be overwhelmed and DNA damage becomes inevitable.

That’s why cells also have proofreading machines that scan our DNA code, looking for faults and calling on molecular repair teams to fix any damage that’s found.

These very effective systems have evolved over billions of years, but they’re not foolproof, and mistakes can slip through the net. Sometimes a subtle genetic change might go unnoticed, or there could be so much damage that the repair machinery can’t cope. But even if this happens, there are further checks in place to stop the damaged cell from dividing and potentially leading to a cancer. For example, the cell can be forced to commit suicide so that it can’t pass on its faulty DNA to new cells.

But even then, on rare occasions, some damaged cells can slip past these checks.

That’s when the immune system swoops in, spying on cells that appear out of the ordinary and wiping them out. Frustratingly, cancer cells have evolved their own ways to defend from immune attack, such as dressing up in molecules that form an invisibility cloak. Ultimately, these can allow cancerous cells to evade destruction and go on to develop into the disease. But researchers are turning these tricks around and using them to their advantage, in the form of the latest immunotherapy treatments that can target certain cancers