Scotland's leading cancer expert has revealed that clinical trials which could save the lives of 7000 people annually will start within a few years.

Professor Sir David Lane said work on his earlier discoveries into the link between genes and cancer had reached the stage where drug trials in humans were likely to begin in "four to five years" and that cancer will become "more and more a treatable disease".

The world-renowned cancer specialist, who is also the first chief scientist for Cancer Research UK, has said that if the trials are successful, 10 times as many cancer sufferers in the UK - and millions across the world - could be saved.

He said: "Cancer will become more and more a treatable disease where the expected outcome is a successful treatment. We are getting towards that already with breast cancer. It's a combination of early detection, trials, and treatments.

"The difference now is that it feels like we are really on the right track. You can feel the progress. There were times 20 years ago when there weren't drugs coming through and this was such a difficult disease to treat.

"Now we know we are doing the right things. That's not to be complacent because with the ageing population cancer is going to be a major disease, but I am really optimistic about what we are doing."

Dundee University-based Sir David's reputation in cancer research circles is based on his discovery of the p53 gene and work on how it helps prevent cancer by "switching off" the damaged cells that can cause tumours.

He said the development of a molecule known as Nutlin 3 by US scientists was potentially the major breakthrough cancer specialists had been waiting for.

Made by Roche pharmaceuticals, Nutlin 3 allows the p53 gene to perform its anti-cancer functions properly by blocking a protein called MDM2 that inhibits the gene.

Theoretically, Nutlin 3 could be used to help treat virtually all types of cancer, including lung, leukaemia, breast and colon. Approximately half of all cancers involve the p53 gene being blocked by MDM2.

Professor Lane said the fact that Nutlin 3 works well has led to "a lot of excitement" in cancer research and the next step was to make sure it is safe and effective in humans.

He said: "There are things coming to clinical trial soon and that's very exciting. I expect in the next four or five years there will be clinical trials of drugs that work by turning on p53. It's very clear that it's getting very close now and that's a big excitement.

"The thing we would start with would be trials of leukaemia because it's easier to monitor how drugs are working there by taking tumour cells from the blood and seeing if they are being damaged."

Last night, Dr Karen Vousden, director of the Beatson Institute for Cancer Research in Glasgow, said: "There are very few types of cancer that would not be helped by this. It could benefit up to 50% of all cancer cases. Potentially this could have an enormous impact. You can't help but be excited by this."

Andrea Stiglianou, who is co-ordinator of the Leukaemia Society, said: "Anything that leads towards better treatments and enables people to lead better quality lives is welcomed. Sadly, we are still losing patients, so this is welcomed 100%."