People with mental illness are nearly 25% less likely to receive cancer screening than those in the general population. Results from a large international study suggest this is one explanation for why people with mental illness tend to die 15-20 years earlier than other people.
The study included more than 4.5 million people across the world. It investigated why people with mental illness are almost twice as likely to die from cancer as the general population, even though they are not more likely to develop the disease.
Health care professionals have suspected that lack of screening is the reason behind poor outcomes from cancer, but this is the first study to confirm it. The researchers hope their results will raise awareness of the lack of screening received by people with many mental illnesses, including schizophrenia and depression. They suggest it should lead to further work on how to increase cancer screening in people with psychiatric disorders.
What’s the issue?
Cancer kills more people with mental illness than people without. One possible reason for this is the lack of screening among people in this group. They often have their tumours discovered much later than other people, which can limit their treatment options and reduce their chances of survival. There are other possible explanations, such as differences in care, and whether people with mental illnesses are less likely to receive surgery, radiotherapy or chemotherapy. Before this study, the relative importance of these or other possibilities was not known.
The study provides information that could be used to better protect the physical health of people with mental illness. The information is useful to healthcare professionals, people with mental illness and their families.
This analysis pooled and re-analysed data from 47 previous research projects from around the world. It included a total of 501,599 adults with a mental illness and 4,216,280 with no diagnosed psychiatric problems.
People with a mental illness were significantly less likely to be screened for cancer than those in the general population:
- overall, a person with a mental illness was 25% less likely to receive cancer screening
- the largest difference was for women with schizophrenia, who were half as likely to receive breast cancer screening as someone in the general population
- people with mood disorders, including depression, also received less cancer screening, though the screening gap was smaller
- the gap was particularly significant for breast cancer because screening rates for that disease are relatively high
- the smallest differences were seen in cancers such as colorectal cancer for which screening is relatively rare
- screening rates for cervical cancer were relatively high among women with schizophrenia and this could possibly inform other screening services.
Why is this important?
The study provides robust evidence of the scale of the problem. The researchers expect their findings to prompt discussion among healthcare professionals, especially as the study comes during a time of increased attention to mental health from policy makers and the public. It suggests that better screening for people with mental illness could prevent this vulnerable population being left further behind.
By showing that the screening gap extends to people with common mood disorders, the study shows that vast numbers of people are affected – more than 264 million people around the world have depression. Increased screening in these populations could therefore have a big impact on cancer survival rates.
The researchers stress that their findings are also important for the general public, especially people with a family member affected by mental illness. Greater awareness of the lack of screening will help, they say, because the partners, parents and children of vulnerable people – for example women with schizophrenia – can then offer greater support, such as by helping them to make and keep appointments.
The study demonstrates the need for action to close the screening gap and provides a solid evidence base to devise and test new strategies to do so.
Healthcare professionals need to identify the reasons why patients with a mental illness receive less cancer screening. Once identified, they need to change practice to lower the barriers to care.
Many patients with psychoses find it extremely difficult to make and keep an appointment outside the psychiatric care system, with unfamiliar people at a different location. Tailored interventions for people with schizophrenia might help. Mobile mammography vans, or collaborative care models in which patients can meet with psychiatrists and oncologists together, might make screening for breast cancer more accessible.
The study could boost political support for the idea that people living with a mental illness need wider support as a disadvantaged population.
You may be interested to read
The full paper: Solmi M, and others. Disparities in cancer screening in people with mental illness across the world versus the general population: prevalence and comparative meta-analysis including 4 717 839 people. Lancet Psychiatry 2020; 7:52-63.
Firth J, and others. The Lancet Psychiatry Commission: a blueprint for protecting physical health in people with mental illness. Lancet Psychiatry 2019;6:675-712
Lamontagne-Godwin F, and others. Interventions to increase access to or uptake of physical health screening in people with severe mental illness: a realist review. BMJ Open 2018;8:e019412
An example of an informed choice leaflet and video to increase cervical cancer screening uptake in people who find it hard to attend screening, developed as part of a project on mental health-friendly screening resources at the University of Surrey
Conflict of interest
This research was supported by the NIHR Biomedical Research Centre at South London and Maudsley NHS Foundation Trust, and a Clinical Lectureship awarded to author Brendon Stubbs jointly by the NIHR and Health Education England. Brendon Stubbs is also supported by the NIHR South London Collaboration for Leadership in Applied Health Research and Care funding.