Wednesday, 13 March, 2002 Doctors accused of cancer trial bias Results of clinical trials decide how effective a drug is New cancer treatments may be less effective than thought because doctors are unintentionally skewing the results of clinical tests. Experts say their subconscious desire for the latest drug to outperform an older treatment actually influences the way they measure how patients respond to it. There are calls for trials to be conducted far more strictly in order to drive out this bias. Research in the journal "Annals of Oncology" looked at how a particular breast cancer drug performed, both in its early trials in the 1970s, and then in subsequent decades. Remarkably, although the drug appeared to perform well at the outset, for every five years that passed, the chances of a patient responding to it fell by more than 10%. Most of the fall was in the group of patients who had only partially responded to the drug. The study authors, from the Mario Negri Institute in Milan, said that while the complete disappearance of a tumour was unmistakeable, assessing the reduction in size was far more subjective. This, they wrote, made it far easier for the doctor's hopes for a successful trial to influence their measurements. The "gold standard" in these kinds of drug trials is the so-called "double blind" trial. In cancer trials, normally the existing drug is pitted against the new one - each patient receives one or the other. This is organised in such a way that neither the researcher, nor the patient, knows whether they are on the old drug or the new one. This means that the trial results cannot be influenced either consciously or subconsciously by either doctor or patient. However, the Italian team found that, out of 29 trials of this particular drug, only one had used this double blind approach, and only two others had the records of patients been sent to other experts to be audited. This rarity of double blind trials is not confined simply to this drug - an early analysis of 189 trials involving chemotherapy and hormone therapy revealed a similar division. Dr Roldano Fossati, who led the research, said: "Since indirect evidence for the existence of a wish bias emerged from our analysis, we believe that blinding should be strongly recommended for any subjective endpoint assessment such as response, time to progression of disease, and so on." He said that this drive was important to guarantee objectivity and "maintain public confidence". In the UK, Cancer Research UK is one of the largest bodies running clinical trials of new drugs. Its clinical trials director, Dr Kate Law, told BBC News Online that it would be difficult to achieve this. She said: "It would be very expensive, because it would mean hiring a separate doctor specifically for each trial as doctors obviously know which treatment they are giving each patient. "It's an interesting paper and certainly deserves to be considered further." Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.