Millions taking one of UK's most common medications could be saved from cancer, study suggests

Daily Mail​

21-05-2025

Taking antidepressants could help the body fight off cancer, a study has suggested.
Experts found selective serotonin reuptake inhibitors (SSRIs), one of the most common types of the drug, were found to have significantly improved the ability of T cells to fight cancer and suppress tumour growth.
T cells are a type of white blood cell that play a major role in helping the immune system identify and kill infections and cancer cells.
'It turns out SSRIs don't just make our brains happier, they also make our T cells happier—even while they're fighting tumours,' said Dr Lili Yang, senior author of the new study at University of California.
'These drugs have been widely and safely used to treat depression for decades, so repurposing them for cancer would be a lot easier than developing an entirely new therapy,' she added.
Antidepressants are typically taken for mood disorders as the drug increase levels of serotonin—the brain's 'happiness hormone'—by blocking the activity of a protein called serotonin transporter, or SERT.
But the study sought to explore if this process could also influence other parts of the body including digestion, metabolism and immune activity.
The researchers, who published their findings in the journal Cell noticed that immune cells isolated from tumours had higher levels of serotonin-regulating molecules.
Dr Bo Li, another author of the study explained: 'SERT has one job—to transport serotonin.
'SERT made for an especially attractive target because the drugs that act on it—SSRIs—are widely used with minimal side effects.'
The researchers tested SSRIs in mouse and human tumour models representing melanoma, breast, prostate, colon and bladder cancer.
In lab tests on tumours the researchers found SSRI treatment reduced average tumour size by over 50 per cent and made the cancer-fighting T cells more effective at killing cancer.
'SSRIs made the killer T cells happier in the otherwise oppressive tumour environment by increasing their access to serotonin signals, reinvigorating them to fight and kill cancer cells,' said Dr Yang.
The researchers also found SSRIs boosted the effectiveness of existing cancer therapies.
They tested a combination of an SSRI and a treatment called anti-PD-1 antibody in mice with cancer.
This antibody therapy works by blocking immune checkpoint molecules that normally suppress immune cell activity, therefore allowing T cells to attack tumours more effectively.
By adding SSRIs to this researchers significantly reduced tumour size in all treated mice and even achieved complete remission in some cases.
People with depression are thought to have low levels of serotonin, though there is scientific debate over this, and SSRIs combat this by boosting these levels.
While the study suggested SSRIs could one day be used to help treat cancer others have linked their long term usage to health problems.
Some experts suspect that the drugs could be causing too much serotonin to be released, with negative consequences for people's health.
Previous studies have linked their use to health issues including heart problems in young people alongside long-term and even permanent sexual dysfunction.
Health service figures show antidepressants are one of the most commonly taken medications in the UK.
Official data suggests as 8.7 million people in England were prescribed the medication—about 15 per cent of the total population.
In the US an estimated one in eight people are currently taking an antidepressant, according to the Centers for Disease Control.
More than 400,000 people are diagnosed with cancer each year in the UK, according to Macmillan Cancer Support.