The team from Edinburgh and Oxford Universities argue depression is often overlooked but could be treated at a fraction of the cost of cancer drugs.
Their report, based on data of 21,000 cancer patients in Scotland, suggests a new nurse-led treatment could help thousands of people.
They found that 6%-13% of people with cancer had clinical depression, compared with just 2% of the general population at any time.
But researchers added that 75% of people reporting these symptoms were not receiving treatment, partly because they did not consider seeking help and professionals did not pick up on their illness.
Study lead Dr Stefan Symeonides said: “Day-to-day oncologists like myself see the profound impact depression can have on a patient with cancer.
“[This is] a huge area of unmet need missed by current practice.”
Further reading: Cancer survival rates lower for people with severe mental illness
The reports also show that, even when given a diagnosis and standard NHS treatment, the majority did not feel better.
Therapy offered in the nurse-led approach halved the depression scores of more than 60% in the study who said they were “less anxious, less fatigued and experienced less pain”. Only 17% of those who had standard NHS care had similar results.
The new intensive, tailored approach is delivered by a trained cancer nurse and involves the wider medical team, including:
- antidepressant drugs
- encouraging patients to become as active as they can be
- problem-solving therapy
Their final paper suggests the therapy improves quality of life, regardless of how good a patient's prognosis is. The therapy would cost around £600 per patient.
Jacqui Graves, of the Macmillan Cancer Support charity, said: “It is heart-breaking to think cancer patients who are already dealing with the toughest fight of their lives are also struggling with depression, without adequate support. Anyone experiencing depression should get in touch with their GP.”