Researchers at the Erasmus Medical Centre in Rotterdam, the Netherlands, have found that doctors can gauge breast cancer victims' response to a vital drug by giving them cough syrup. The body deals with dextromethorphan-the active ingredient in cough syrup-in the same way that it deals with tamoxifen.
Tamoxifen helps improve breast cancer survival rates by blocking the effects of oestrogen, the female sex hormone which can stimulate the growth of certain tumours. Because people respond differently to the drug, individuals can require different doses of it in order to achieve the same effect. Administering more accurate doses could reduce the side-effects of the drug.
Researchers gave breast cancer patients a small dose of cough syrup two hours prior to their tamoxifen pills, then took blood samples to see whether the processing of the two substances was comparable. They found that levels of dextromethorphan accurately predicted levels of the chemicals produced when tamoxifen is broken down.
"Tamoxifen is prescribed to women for as much as five years, so it is highly important to know beforehand if the therapy is going to be effective", said lead researcher Anne-Joy de Graan. "When it is known that a woman metabolises tamoxifen poorly, a switch in drugs or an increase in dose can be considered."
The research will be refined with a larger group of patients. the findings could help doctors improve the success rate of breast cancer treatment, and spare patients unnecessary side effects.