In primary care the key areas of concern for both doctors and patients are delay in diagnosing cancer, referring high risk patients quickly, and keeping investigation to a minimum. There have been few valid studies to assist decision-making in primary care, either to get a patient referred quickly or to assist in making sure an anxious patient is effectively reassured. CANDID seeks to work out which of the symptoms and examination findings are the most effective in predicting lung or colon cancer. To decide on the best clinical information to collect, evidence gathered by two preliminary studies - interviews with cancer patients and consensus from a group of GPs and cancer experts - has been used to inform data collection for the study.

Practices will invite patients to take part in the study and collect clinical information using standardised internet based forms. Willing participants will complete lifestyle questionnaires and provide blood or saliva samples for genetic analysis.

The National Cancer Registry will then be monitored and GP notes reviewed to see which patients develop cancer, and statistical analysis will determine the set of clinical variables that provide the best estimate of cancer risk. The clinical prediction 'rules' or decision aids developed from these studies will then be tested with a further 2,000 patients for each condition, for validity.

The study is being led by the University of Southampton and will be run by researchers across nine different centres: Birmingham, Warwick, Bristol, Keele, London, Manchester, Nottingham, Oxford and Southampton, and is funded by the National School for Primary Care Research.

The study aims to recruit 20,000 patients in total consulting their GP with either lung symptoms or bowel symptoms. Participants in our area will be identified from 50 practices across the Primary Care Research Network Central England region and South Cheshire.

For further information, please contact Jenny Lee, research facilitator email: jennifer.lee@warwick.ac.uk, telephone 02476 575 919