Doctors and mental health groups are urging patients on drugs such as Prozac to keep taking their medication despite a British study linking it to an increased risk of cancer.
Laboratory research has shown that the pill and similar antidepressants stimulate the growth of tumours by blocking the body's natural ability
to kill cancer cells.
In New Zealand, more than 600,000 prescriptions for antidepressants are given every year, at a cost of about $24 million.
Professor John Gordon of Birmingham University told The Scotsman newspaper that in test-tube experiments, Prozac and other widely-prescribed selective serotonin re-uptake inhibitors (SSRIs), encouraged growth of a type of cancer called Burkitt's lymphoma.
Serotonin is a naturally occurring chemical that regulates people's moods. Those with too little often suffer depression.
Drugs such as Prozac work by preventing serotonin from being reabsorbed too quickly by nerve cells in the brain.
However, the study, to be published this week in Blood, the journal of the American Haematology Society, found that serotonin was a key driver in stimulating a natural cell "suicide" process for controlling the runaway growth that leads to cancer.
The antidepressants prevented serotonin from being absorbed into the cancer cells, leading to a more vigorous growth of the tumours.
But New Zealand Medical Association chairman John Adams, who is also a psychiatrist, said on Thursday that people should not stop taking their medication because of a limited study.
"People need to keep taking their medication because stopping... increases the danger of dysfunction and, in severe cases, suicide," he said.
Dr Adams said Prozac and similar drugs were effective, safe and had low side-effects.
Angela Kelly, from the Wellington Mental Health Consumers Union, said people should consult their doctor before changing their medication regime.
"If they are coming off for whatever reason, it needs to be on a diminishing scale rather than just stopping it."
Ministry of Health spokesman Stewart Jessamine said the Ministry had no concerns about the use of Prozac and other SSRI drugs. "It's a very preliminary piece of research on which we should not be basing any clinical decisions."
Dr Jessamine said SSRIs had been on the market for at least 10 years and large-scale epidemiological studies had found no link between them and cancer.
Burkitt's lymphoma was not a very common form of cancer, he said.
It is an aggressive tumour of the white blood cells that manifests itself in large tumours in the jaw and abdomen.
- NZPA
Doctors and mental health groups are urging patients on drugs such as Prozac to keep taking their medication despite a British study linking it to an increased risk of cancer.
Laboratory research has shown that the pill and similar antidepressants stimulate the growth of tumours by blocking the body's natural ability
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