Doctors may need better information on survival
Doctors are too worried to give patients with terminal cancer precise information about the benefits of extra chemotherapy, say researchers.
Two-thirds of those surveyed by Bristol University scientists were given no information or just vague promises of "extra time" with loved ones.
Doctors felt telling patients treatment would offer only weeks or months could "destroy hope", the researchers said.
Macmillan Cancer Support said national data on survival times was needed.
The study focused on 37 patients with terminal colorectal, lung and pancreatic cancer.
A researcher interviewed each patient before they saw their oncologist, then recorded the consultation with the health professional where further treatment would have been discussed.
Six patients out of the 37 were given a more precise estimate in weeks or months of their likely extra survival time with chemotherapy, while five were given a slightly less precise idea of timing.
However, for the remainder of the consultations, there was either no discussion of the effects of the chemotherapy on survival time, or very vague descriptions - for instance, saying that the drug could "buy you some time".
The researchers said doctors were worried that giving precise numbers could "destroy hope".
They wrote: "Giving comprehensible and appropriate information about survival benefit is extremely difficult - however, the reluctance to address these difficulties and sensitivities may be hampering patients' ability to make informed decisions about their future treatment."
Professor Jane Maher, Chief Medical Officer at Macmillan Cancer Support, said: "I'd like all patients with incurable cancer to have the information they need to make a decision about whether to have this treatment.
"But this needs nationally agreed, and regularly updated, statistics, and earlier conversations with their doctor about the pros and cons of treatment in the last month.
"At the moment, much depends on the doctor you see."
A spokesman for Cancer Research UK, which funded the study, said: "This small but interesting study sheds some light on the particular difficulties in communicating information about palliative chemotherapy treatment decisions.
"Further work is needed to help us better understand the differing priorities of patients considering such treatments and the judgements health professionals make in their approach in these difficult situations."