But the RNID, the national charity for deaf and hard of hearing people, said that the pharmaceutical industry was "dragging its heals" in developing treatments to tackle the problem. They have now produced a business report claiming that making such protective agents could generate revenues of at least £500 million for the drugs industry as well as help protect cancer patients.

It has been known for some time that cisplatin - a platinum-based chemotherapy and one of the best anti-tumour treatments - can cause damage to the inner ear. This can lead to balance problems, tinnitus and hearing loss - in some cases profound deafness. The drug is used for the treatment of around 68,000 cancer patients each year in the UK - and is used in around 30% of all childhood cancers and 25% of adult cancers. Cisplatin is used to treat cancer including, lung, bladder, ovary, testis, liver and bone.

It is estimated that at least a quarter of children treated with the drug suffer some hearing loss or tinnitus, though some studies suggest it may be as high as 100% over time. In adults, it is estimated that hearing problems could be found in between 11% and 91% of those treated with cisplatin.

RNID said there were ways of preventing this ototoxicity - damage to the sensory hair cells of the inner ear caused by drugs. But work in this area was slow in being developed, with the pharmaceutical industry doing little to progress it further.

Munna Vio, the RNID's commercial research manager, said: "Thousands of survivors are being left with unnecessary hearing damage. RNID's research indicates that if a suitable drug was approved that effectively protected against hearing loss but did not interfere with the chemotherapy, oncologists would use it across the board for all cancer treated with cisplatin. The pharmaceutical industry should seize this opportunity to deliver vital drugs to protect the hearing of cancer patients. RNID is committed to funding research into this area and is already supporting projects that could lead to new ways of protecting hearing from ototoxic drugs."

Dr Penelope Brock, a consultant paediatric oncologist at Great Ormond Street Hospital in London, has been conducting research into the extent of hearing loss caused by chemotherapy for several years. She said they had found an "alarming" level of hearing loss caused by cisplatin.

"In some cases the hearing loss wasn't picked up and we discovered that the children were losing their hearing so badly that they were stopping speaking or not learning how to speak," Dr Brock said.

She added: "The cure rate for childhood cancer has improved considerably over past decades and now exceeds 70%. Cisplatin has been and will continue to be a major contributor. However, this cure is not without cost to the child. Permanent side effects are the most damaging, and hearing loss is one which affects everyday life and development. Children who survive cancer are determined to make the most of the life they have been given, but struggle to compete in an ever increasingly competitive world. Preventing hearing loss would transform their lives and futures."

From Daily Mail