He said that the way women lived could have a direct bearing on their p53 gene.

BBC: Key cancer gene 'link to poverty'

The researchers found that around 20% of CLL tumours had a faulty ATM gene, and another 10-15% had an abnormality in the p53 gene.

BBC: Gene research

But a defective ATM gene can interfere with p53 thereby allowing potentially cancerous cells to multiply.

BBC: Gene research