Ritalin and Cancer Risks

American Academy of Pediatrics Guidelines for Treating Behavioral Disorders in Children with Ritalin Ignores Evidence of Cancer Risks warns Samuel S. Epstein, M.D.

Based on an industry-funded multi-university trial on 282 pre-teen children treated with Ritalin for attention deficit/hyperactivity disorders (ADHD), just published in Pediatrics, the American Academy of Pediatrics has endorsed the use of the drug. However, the Academy ignores clear evidence of the drug's cancer risks of which parents, teachers and school nurses, besides most pediatricians and psychiatrists, still remain uninformed and unaware.

Some 40 years after the drug was first marketed by Ciba Geigy, carcinogenicity tests were conducted at the tax payer's expense by the National Toxicology Program, the results of which were published in 1995. Adult mice were fed Ritalin over a two-year period at dosages close to those prescribed to children. The mice developed a statistically significant incidence of liver abnormalities and tumors, including highly aggressive rare cancers known as hepatoblastomas. These findings are particularly disturbing as the tests were conducted on adult, rather than young mice which would be expected to be much more sensitive to carcinogenic effects. The National Toxicology Program concluded that Ritalin is a "possible human carcinogen," and recommended the need for further research. While still insisting that the drug is safe, the Food and Drug Administration admitted that these findings signal "carcinogenic potential," and required a statement to this effect in the drug's package insert. However, these inserts are not seen by parents or nurses.

The Physicians' Desk Reference admits evidence on the carcinogenicity of Ritalin, now manufactured by Novartis, qualified by the statement that "the significance of these results is unknown," apparently not recognizing that this is more alarming than reassuring. Apart from cancer risks, there is also suggestive evidence that Ritalin induces genetic damage in blood cells of Ritalin-treated children.

Concerns on Ritalin's cancer risk are more acute in view of the millions of children treated annually with the drug and the escalating incidence of childhood cancer, by some 35% over the last few decades, quite apart from delayed risks of cancer in adult life. These risks are compounded by the availability of alternative safe and effective procedures, notably behavior modification and biofeedback.

There is no justification for prescribing Ritalin, even by highly qualified pediatricians and psychiatrists, unless parents have been explicitly informed of the drug's cancer risks. Otherwise, prescribing Ritalin constitutes unarguable medical malpractice.