New University of Otago research led by Dr Ruth Cunningham about the role of mental illness in surviving cancer, has a number of implications for New Zealand GPs and, more broadly, for health sector policy and practice.  

It’s well-known that experience of mental illness is associated with premature mortality and worse outcomes from many physical health conditions including heart disease, diabetes and cancer. 

Dr Cunningham’s work investigated survival after cancer diagnosis among mental health service users, and found unacceptably high death rates in this group. For example, the study found that the risk of death from colorectal and breast cancers is more than doubled for people with schizophrenia and bipolar disorder, compared with the general population.

There are likely to be a number of factors contributing to this disparity.  Delayed cancer diagnosis is contributing to survival differences for people with schizophrenia and bipolar disorder. A high burden of physical disease is also contributing to worse cancer survival for all people using mental health services compared to the general population.  

“We were not able to investigate the role of differences in cancer treatment in this study, but international evidence suggests that this may also be a factor in poor cancer survival,” Dr Cunningham said.

The findings from this study are consistent with other studies demonstrating that cancer mortality is disproportionately increased, compared to the number of people with a history of mental illness who are diagnosed with cancer. It highlights an important health equity issue which has received little policy attention in New Zealand. 

General practitioners have a role in ensuring timely diagnosis of cancers and optimal management of other physical health conditions in people being cared for by mental health services.

Further qualitative research is currently underway to examine the pathway of care for women with a history of mental illness and breast cancer.

The University of Otago and the Royal New Zealand College of General Practitioners are part of the Equally Well collaborative – a group of more than 70 New Zealand organisations working together to improve physical health outcomes for people with serious mental health and addiction problems. 

Dr Ruth Cunningham is a senior research fellow in the Department of Public Health, University of Otago, Wellington.