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Researcher: Report of Prozac Link to Cancer is Wrong

Press reports mistakenly cite such a connection

WEDNESDAY, March 26, 2002 (HealthDayNews) -- An American scientist involved in an international research project expressed outrage today at London media reports that said his study potentially linked common antidepressants to brain cancer.

Randy Blakely, director of the Center for Molecular Neuroscience at Vanderbilt University in Nashville, Tenn., told HealthDay, "There is no link to cancer for these medications."

"As one of the scientists associated with the study, let me just make an emphatic statement that the study has no bearing, as far as we know, on brain cancer, nor does it have any bearing at all on the safety of SSRI medications, which are in fact extremely valuable to people suffering from depression," Blakely said.

At issue were the antidepressants known as selective serotonin reuptake inhibitors (SSRIs), which include well-known drugs like Prozac, Paxil and Celexa, and a study published in the online edition of Blood, the journal of the American Society of Hematology.

The controversy arose earlier today, after at least one London newspaper, The Independent, misinterpreted the research results in its report on the findings.

The story claimed the study potentially linked drugs like Prozac to brain cancer.

However, the actual research, which Blakely conducted in concert with a group of respected British scientists, including Prof. John Gordon of the University of Birmingham, made no such connections. Instead, it involved laboratory experiments on a line of cells contained in a disease known as Birkett's lymphoma, an extremely rare type of cancer.

The study, said Blakely, found that "a special class of lymphoid cells in culture respond to serotonin through apoptosis [cell death] and that the serotonin transporter that is the target of Prozac will block that action."

More simply put, the research said serotonin may play a role in helping to destroy cancer cells involved in Burkitt's lymphoma and that antidepressant medications like Prozac, may, in fact, block that action from occurring.

However, Blakely said, "There is no indication that this behavior is found anywhere in the nervous system or in the brain... So there is absolutely no reason to extend from the data on the antidepressants [these findings] to brain diseases, particularly brain cancer, which is a very different kind of disorder."

In the online Independent story, the headline proclaimed "Scientists find Prozac 'link' to brain tumours". At least one wire service also picked up the report, broadcasting further the news of a potential link.

The BBC, however, brought in the voice of Prof. Gordon, who said no link had been proven. He also urged people who take antidepressants to keep taking their medications.

Gordon also told the BBC that in addition to his own research, he "looked at a number of large-scale studies looking specifically at these drugs in relation to cancer, and there is nothing to suggest that they increase cancer risk."

And Blakely added, "It's really outrageous to extend to brain cancer... what is being studied by Dr. Gordon in his Birkett's model."

Burkitt's lymphoma is an extremely rare cancer that afflicts mostly children living in central Africa. It often begins with a lesion in the jaw that quickly progresses to the bony cavity that encloses the eye, and occasionally to other parts of the head. Sometimes, the disease may encompass the bone marrow and central nervous system, which could then worsen the outcome of the disease.

In the research conducted by Gordon and Blakely, cells containing Burkitt's lymphoma were combined, in a test tube, with the mood-elevating brain chemical serotonin. The researchers noted that the serotonin was able to get inside the cells, and cause them to die. Medications like Prozac, Paxil and Celexa, which work to keep serotonin levels from being reabsorbed by brain cells, might hamper that process.

This, however, said Blakely, is a far cry from any notion that the drugs could play any role in instigating or encouraging the growth of a brain tumor, which, in fact, is not in any way even related to Burkitt's lymphoma.

"There is a much greater problem with people not taking their antidepressants than in them worrying about brain cancer," Blakely added.

Statements issued by Prozac-maker Eli Lilly in response to the early news reports underscore Blakely's statements.

The drug company told the BBC that "there is no medical or scientific evidence of a connection between fluoxetine (Prozac) and cancer," and further stated that the results of its own long-term studies have provided "conclusive evidence that fluoxetine [Prozac] is not a cancer initiator or promoter."

All those involved in the research say it is imperative that patients who are taking SSRIs, including Prozac and Paxil, continue to take their medication as prescribed and to do so without fear of brain cancer.

What To Do

For more information about serotonin and its effects on emotions, take a look at this site from California State University at Chico.

Here is more information about Burkitt's lymphoma.

SOURCES: Randy Blakely, Ph.D., professor, and director, Center for Molecular Neuroscience, Vanderbilt University, Nashville, Tenn.; March 26, 2002, The Independent, London
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