A British study says large numbers of cancer patients who suffer from depression never receive any kind of effective treatment.

Large numbers of cancer patients suffer from major depression and in the vast majority of cases their mental anguish is being overlooked or ignored, a study has found.

A survey of more than 21,000 patients in Scotland found rates of clinical depression ranging from 6 per cent to 13 per cent, compared with a prevalence of just 2 per cent in the general population.

Of the 1130 who had been diagnosed, almost three quarters were not receiving any kind of effective treatment.

The findings were revealed as doctors reported promising results from two trials testing a new approach to managing depression in cancer patients.

SMaRT (Symptom Management Research Trials) Oncology 2 and 3 used specially trained nurses to deliver a range of psychiatric care including behavioural therapies and medication.

Professor Michael Sharpe, from Oxford University, one of the researchers whose findings are reported in the journal The Lancet Psychiatry, said: "Major depression is really quite common in people with cancer and the perhaps surprising finding is that most of it goes untreated. The outcome with usual care is poor."

In the first of a series of three papers, the researchers outlined findings from data on 21,151 men and women with lung, breast, bowel, genito-urinary or gynaecological cancers.

All the patients had participated in routine screening for depression between May 2008 and August 2011.

Those with lung cancer had the highest prevalence of major depression (13.1 per cent) followed by patients with gynaecological cancers (10.9 per cent) and breast cancer (9.3 per cent).

Seven per cent of patients with bowel cancer were seriously depressed, as were 5.6 per cent of individuals with genito-urinary cancers.

At the time of screening, 73 per cent of 1538 patients diagnosed with depression for whom information about treatment was available were not receiving "potentially effective" therapy for their mental state.

The new treatment approach involves talking to patients, helping them to be active and engaged, "problem solving therapy" aimed at putting people more in control of their situation, and intensive monitoring for up to a year.

Patients randomly recruited to the program had their progress compared with those who continued to undergo "usual care". This generally involves GPs being in charge and prescribing antidepressants or referring patients to mental health services if necessary.

For 500 patients with a good cancer prognosis, 17.3 per cent of those getting usual care saw a significant improvement in their scores of depression symptoms after six months. But 62 per cent of those allocated the new therapy program experienced a similar positive outcome - a difference of 45 per cent.

They were also less anxious, less fatigued, less afflicted by pain, and their quality of life was greatly enhanced. The difference in improvement was sustained for the 12 month follow-up period.

The second trial, SMaRT Oncology 3, focused over a 32-week period on patients with lung cancer with poor prognosis. Depression severity was found to be "significantly lower" in those assigned to the new treatment compared with those undergoing "usual care".

SMaRT Oncology 3 leader Dr Jane Walker, from Oxford University, said: "Patients with lung cancer often have a poor prognosis. If they also have major depression, that can blight the time they have left to live."

Copyright 2014 AAP