Cancer patients taking part in early-stage trials often have unrealistic expectations about the effectiveness of the treatments they are testing, a study has shown.
Phase I clinical trials, the next step up after experiments involving laboratory animals, produce typical cancer response rates of between 4% and 20%.
Enrolled patients, who often have advanced disease that is not responding to standard therapy, survive for around six months on average.
But a new study suggests that cancer patients volunteering for Phase I trials anticipate much better outcomes. Nearly half (47%) of 301 potential trial patients questioned believed their tumours would shrink, and their hopes were raised higher after consultation with clinicians.
Overall, patients were keen to consider trials, with up to 84% willing to enrol.
Lead researcher Dr Udai Banerji, from The Royal Marsden NHS Foundation Trust and the Institute of Cancer Research, London, said: "There is a positive message in this, which is that 84% of patients are willing to participate in Phase I oncology studies after a discussion with clinical and nursing staff who lay out the conservative estimates of benefit and requirements of hospital visits.
"This is good for current and future patients and cancer medicine in general."
However, he added: "The high percentage of patients expecting their tumours to shrink was a sobering finding. This creates a challenge for healthcare professionals to manage expectations but to do so without being patronising or dismissing human hope."
The findings, published online in the American Cancer Society journal Cancer, point to the need to improve patient information and consent forms, said the authors.
Phase I trials are designed to assess the potential of new treatments that have never before been tested on humans and tend to focus on safety rather than effectiveness.
The trials start with low doses of a treatment which are increased until a recommended dose for a next stage Phase II trial is established.
Healthcare professionals are duty-bound to ensure that patients are properly informed about the risks and benefits of taking part in a Phase I trial.