The study, by King’s College London's Institute of Psychiatry (IoP) and published in BMJ Open, suggests that problems arise during care, rather than being associated with late diagnosis or screening, and highlights the health inequalities faced by people with mental illness.  

People with serious mental illness (SMI), including bipolar disorder, schizophrenia and schizo-affective disorder, have a life expectancy 15-20 years lower than people without mental illness. Premature mortality among people with mental disorders is mainly due to poor physical health, with conditions such as cancer or heart disease substantially more common than suicide or violence. 

The study looked at 28,477 cancer cases, including lung, breast, prostate and bowel cancer, in people aged 15 or over. Of these, 2,206 individuals had been previously assessed or treated in secondary mental health care, 125 for severe mental illness. 

The researchers found no significant difference in how advanced the cancer was at diagnosis for people with a history of mental illness, compared to those without. But they did find that people with mental health disorders had worse survival after cancer diagnosis, suggesting that the problems arise during their care, rather than being due to late screening or diagnosis. 

Compared to cancer patients with no history of mental illness, people with SMI had a 74% higher risk of death over the 4-5 year follow-up period. People with depression (30% higher), dementia (66% higher) and substance use disorders (42% higher) also had worse cancer survival rates. 

Professor Robert Stewart, senior author of the paper from the IoP at King's, said the next step is to understand the barriers to care for people with mental health problems. “There are many factors to consider, including how the symptoms of mental illness and medication may affect cancer treatment, as well as the considerable social disadvantage and stigma faced by people with severe mental illness. 

“It is unacceptable that there is such a difference between cancer survival rates for people with mental illness and people without. We need to make sure that people with mental health problems have access to the same standard, quality and range of healthcare services as everyone else.”

Reference: Chang C-K et al (2014) A Cohort study on mental disorders, stage of cancer at diagnosis and subsequent survival. BMJ Open doi:10.1136/bmjopen-2013-004295 http://bmjopen.bmj.com/content/4/1/e004295.full.pdf