WASHINGTON - CANCER patients' state of mind has no influence on their survival chances, according to a US study released on Monday that contradicted a widespread belief in the power of positive thinking.

Researchers led by James Coyne, professor of psychology at the University of Pennsylvania, found no correlation to a cancer victim's mental wellbeing and their ultimate chances of beating off the disease.

'The belief that a patient's psychological state can impact the course and outcome of their cancer is one that has been prominent among patients and medical professionals alike,' Prof Coyne wrote in the study.

'While there can be lots of emotional and social benefits of psychotherapy, patients should not seek such experiences solely on the expectation that they are extending their lives,' he said.

The study analysed 1,093 sufferers of cancer in the head or neck, of whom 646 died before the research period ended.

The researchers found no link to suggest that those who lived owed their survival to a positive frame of mind, whatever their gender, type of cancer or the stage of their disease.

'While this study may not end the debate, it does provide the strongest evidence to date that psychological factors are not independently prognostic in cancer management,' Prof Coyne said. -- AFP