The report, Paying for Cancer Care, by the oncologist Prof Karol Sikora, identifies 136,000 British patients a year who could benefit from 10 cancer treatments, which are commonly available across Western Europe, but rarely funded by the NHS.
According to estimates, less than 5 per cent are receiving the drugs, with many of those who get them paying privately.
The report, to be submitted to the Government's review of drug funding, has said that demand is such that ministers must change rules that penalise desperate patients who pay for the drugs.
Sikora examined treatments including the bowel cancer drugs Avastin and Erbitux, which could extend the lives of 50,000 people by three to six months.
The National Institute for Health and Clinical Excellence (Nice) rejected the drugs because of their costs between 50,000 pounds and 60,000 pounds per patient.
Two other drugs, Sutent, for advanced kidney cancer, and Tarceva, for lung cancer, which have yet to be assessed by Nice, could extend the lives of 35,000 patients for up to six months.
Ian Beaumont, of the charity Bowel Cancer UK, said that more patients should have access to the drugs.
"These drugs can make a significant difference to length of life but it is not just about that. They can mean the difference between dying in agony or having some kind of quality of life in your last months with your loved ones," the Telegraph quoted Beaumont, as saying.