Expensive chemotherapy does little to improve survival for people with advanced cancer, who often have "unrealistic expectations", an expert has said.
Peter Wise, a former consultant physician at Charing Cross Hospital in London, said spending "six figure" sums on chemotherapy drugs is inappropriate for many people with advanced cancer who will "almost inevitably die" from their tumours.
Chemotherapy - which is one of the cornerstones of cancer treatment and can be used alongside other targeted drugs or radiotherapy - has only been shown to extend life by a few months on average, he said.
Instead of wasting money on these drugs, cash should be ploughed into "under-financed" areas that can actually extend survival, such as prevention, early diagnosis and more prompt treatment of single tumours, he added.
Writing in the British Medical Journal (BMJ), Mr Wise said cancer survival has improved in recent decades, but only a small part of this can be attributed to expensive drugs.
Some 48 new regimens approved by the US Food and Drug Administration (FDA) between 2002 and 2014 led to a typical two months survival benefit, while more historic data shows little evidence of overall benefit of chemotherapy.
Mr Wise also pointed to problems with clinical trials of new drugs, saying that the end result of any trial should be whether survival rates improve.
But "surrogate endpoints" are used as a way of shortening clinical trials and getting drugs to market quickly. These endpoints include patients having early tumour shrinkage and longer periods of time before disease gets worse - known as progression-free survival.
"These endpoints are ... more rapidly available but, with some exceptions, have been shown to correlate poorly with overall survival," Mr Wise said.
"Many drugs approved on the basis of better progression-free survival have been subsequently found not to produce better overall survival than the comparator drug."
He said both US and EU regulators accept these surrogate endpoints for "what are judged to be urgently needed new drugs", while patients who often "overestimate" potential benefits are often not aware of the debilitating side-effects of treatment.
Turning to England, Mr Wise said he was hopeful that the recent integration of the Cancer Drugs Fund into the National Institute of Health and Care Excellence (Nice) might make it possible to monitor the "real world benefit" of drugs.
In conclusion, Mr Wise said: "Many irregularities and competing interests — in pharma, in trials, in government approval, and in the clinical use of cancer drugs — impact ethically on the care and costs of patients with cancer.
"Non-representative clinical trials with imprecise endpoints and misinformed patients with unrealistic expectations compel interventions that are mostly not in their best interests.
"Spending a six figure sum to prolong life by a few weeks or months is already unaffordable, and inappropriate for many of the 20% of the (Western) population who will almost inevitably die from solid tumour metastases."
Mr Wise criticised the way "market-driven" priorities stand above "health-driven" priorities when it comes to treatment, which "do not benefit cancer patients".
His views differ to that of some health experts, who point to the success of chemotherapy for individual cancers, and in combination with other treatments.
In 2015, a UK-led trial funded by Cancer Research UK found that combining a chemotherapy drug with hormone treatment extended the lives of men with advanced prostate cancer by many months,
In the study of 2,962 men, those who received docetaxel plus standard hormone therapy at the start of their treatment lived an average of 10 months longer than those who received only hormone treatment.
For patients whose cancer had already spread beyond the pelvis, the average increase in life expectancy was 22 months.
Emlyn Samuel, senior policy manager at Cancer Research UK, said: "Drugs are vital in cancer treatment. Advances in drug development, with the emergence of immunotherapy and precision drugs, give cancer patients much better prospects.
“It’s crucial that patients don’t miss out on the best treatments for their condition.
"The recent changes to the cancer drugs fund in England are a step in the right direction and we’re monitoring this closely. But we also need further consideration of Nice reform to make sure its processes reflect advances in drug development."