WEDNESDAY, Dec. 19 (HealthDay News) -- People with psychiatric disorders have a 30 percent higher death rate from cancer, even though they are no more likely to develop the disease than others. And the underlying reason may be relatively simple: Their cancer is frequently discovered late, often after it has spread, a new Australian study finds.

It's long been known that people with psychiatric conditions -- ranging from alcohol and drug disorders to depression and schizophrenia -- are less apt to seek regular medical attention and pursue a healthy lifestyle.

As a result, the overall mortality rate in psychiatric patients is much greater than in the general population. Cancer survival typically depends on both early diagnosis and access to effective therapies, the study authors noted.

But researchers haven't been able to pin down the reason why these patients have no greater chance of developing cancer, but are still more likely to die from it. They've wondered: Are psychiatric patients treated differently? Are their concerns taken less seriously? Is it harder for them to get care once they're diagnosed with cancer?

The new research was published online Dec. 17 in the Archives of General Psychiatry.

The problem is most significant in people with the more serious forms of mental illness, such as schizophrenia and bipolar affective disorder, said lead study author Dr. Stephen Kisely, a professor at the University of Queensland, in Australia. "People with severe mental illness may be more disorganized, have less resources [and be] more subject to stigma," he explained.

The challenge for the researchers was to tease out the various lifestyle issues associated with mental illness from the potential physical and health system factors that could be causing the higher fatality rate among psychiatric patients.

A U.S. expert noted the connection between physical and mental health.

"In general, we know that lifespans of people with mental illness are shorter due to lifestyle and access issues, and the side effects of psychotropic treatments," said Dr. Alan Manevitz, a family psychiatrist in New York City. Psychotropic drugs alter chemical levels in the brain that affect mood and behavior.

"Severe mental illness comes with other risk factors," Manevitz said.

For the study, the researchers identified all psychiatric patients in Western Australia who were diagnosed with cancer. Of more than 135,000 new cases of cancer in the region, about 6,600 occurred in those with mental illness. The authors linked those patients' mental health records with cancer registries and selected those whose first contact with mental health services occurred between January 1988 and December 2007.

The researchers compared the patients' health outcomes with those of the general population, accounting for age and gender. They also collected information about the patients' cancer treatment, including whether radiation therapy or chemotherapy was started within 90 days of being diagnosed with cancer, the number of treatment sessions patients received and whether the tumor was surgically removed.

The proportion of psychiatric patients with cancer who already had metastases -- their cancer had spread -- when they were first diagnosed with cancer was significantly higher compared to the general population, the investigators found.

The researchers also found that psychiatric patients were less likely to have surgery to treat the cancer. They found no significant association with socioeconomic status, length of hospital stay or type of care received.

Kisely said he thinks the increased incidence of metastases associated with psychiatric patients was due to both lack of access to health care and to late diagnosis of cancer.

The study, Kisely said, has implications for those who provide health care to people with psychiatric conditions. "Primary care doctors should be aware of the issue and ask about early surgery, and ensure these people get access to screening and specialists should ensure they offer treatment equitably."

Manevitz agreed. "Psychiatrists should not assume other physical issues are being looked at while people are under psychiatric care."

More information

To learn more about mental health problems, visit the U.S. National Library of Medicine.