New York, Dec 5 (IANS): About one-third of patients newly diagnosed with the most common form of lung cancer have moderate to severe symptoms of depression, a new study suggests.

For many of these patients -- particularly those with severe symptoms -- depression occurs in a toxic blend of high levels of anxiety, traumatic stress, impaired day-to-day functioning and significant pain and other physical symptoms, findings published in the journal Lung Cancer showed.

"The results suggest doctors need to screen lung cancer patients for depression and then act to refer patients for care," said study lead author Barbara Andersen from the Ohio State University in the US.

"Some oncologists may have a mindset that 'of course, you're depressed, you have lung cancer.' This may show an under-appreciation of the breadth of depressive symptoms and other difficulties which accompany it," Andersen said.

Patients with moderate or severe depressive symptoms are more likely to have lower quality of life and worse disease outcomes compared to those also diagnosed with lung cancer but with mild or no depressive symptoms.

According to the researchers, data came from 186 patients at one cancer hospital who had been recently diagnosed with advanced-stage non-small cell lung cancer, which accounts for 85 per cent of all lung cancer cases.

Patients completed a telephone survey measuring psychological and physical symptoms, stress and day-to-day functioning.

Results showed that eight per cent of the patients scored at the severe depressive symptom level and 28 per cent had moderate depressive symptoms.

Nearly all (93 per cent) of the patients with severe depression said the depressive symptoms made it difficult to do their work, take care of things at home and get along with other people.

Compared to other cancer patients, those with high levels of depressive symptoms were much more likely to report severe physical symptoms, including 73 per cent who said they experienced 'quite a bit' or 'very much' pain.

Every one of the patients with severe depressive symptoms said they had severe or moderate issues functioning with their usual activities such as work, study, housework and family or leisure activities.

In general, those with moderate depressive symptoms saw negative effects that were somewhat less -- but still significant -- than those with severe symptoms, the study found.

But there were two striking differences between the groups.

One was in the severity of generalised anxiety disorder (or GAD) symptoms, the most common anxiety disorder.

About 11 per cent of those with moderate depressive symptoms had moderate to severe GAD, compared to 73 per cent of patients with severe depressive symptoms.

Second, many fewer of the patients with moderate depressive symptoms had impairments in self care (eight per cent versus 33 per cent in those with severe depressive symptoms), mobility (33 per cent versus 73 per cent) and usual activities (38 per cent versus 100 per cent).