Exposure to asbestos can cause cancer many years later
Chemotherapy treatments which aim to prolong patients' lives and reduce suffering from asbestos-related cancer do not work, UK researchers suggest.
Mesothelioma, caused by asbestos exposure, is usually incurable, but some specialists hope chemo could delay death and improve quality of life.
The study in the Lancet found hundreds of patients saw no benefit.
However, a US expert said other combinations of chemotherapy drugs could work better.
Despite legislation controlling the use of asbestos, there are approximately 2,000 deaths from mesothelioma in the UK every year.
The decades-long delay between exposure and the onset of the disease, means numbers are expected to keep rising for at least half a decade.
Treatment for mesothelioma is aimed principally at reducing its symptoms, and hopefully slowing down the progression of the illness.
It is generally recommended that patients are given steroid drugs and radiotherapy sessions.
The latest study looked at 409 patients, mainly from the UK, who were all given these standard treatments.
Some were additionally given doses of chemotherapy, and the effect on their disease compared.
While the chemotherapy patients did live slightly longer on average than those given just standard treatment, the researchers said the finding did not represent statistical proof, and could be misleading.
There was no improvement in quality of life among the chemotherapy patients.
One of the authors of the study, Dr Richard Stephens from the Medical Research Council Clinical Trials Unit, said: "While thousands are and will be affected by this deadly disease, our trial, which is one of the few large trials ever conducted in this disease, emphasises how difficult mesothelioma is to treat.
"This is mainly because mesothelioma forms in the lining of the lung. This makes it hard to target."
Kate Law, Cancer Research UK's director of clinical trials, added: "These results showed no real benefit from adding these chemotherapy drugs compared with just treating the symptoms of the disease.
"Any treatment can have serious side effects for patients and these findings highlight that people should not have treatment that is not of proven benefit."
However, Dr Nicholas Vogelzang, from the Nevada Cancer Institute, also writing in The Lance said that results from other trials using different combinations of chemotherapy drugs had been more positive.
Professor Mark Britton, of the British Lung Foundation added: "It is worth noting that since this trial began newer treatments are available which can extend survival times by some months, which may be of crucial importance for people with mesothelioma in terms of the time they have to spend with their loved ones."