Impact of a Gene Test for Susceptibility to Lung Cancer in Smokers

• Number of subjects versus controls who are non-smokers at 4 weeks and six months after completion of smoking cessation clinic [ Time Frame: Nine months (from recruitment to completion) ] [ Designated as safety issue: No ]
  Subjects and controls will be reassessed at 4 weeks and six months after the last smoking cessation session to determine how many have genuinely stopped smoking. This will be confirmed at the six month follow up by measuring salivary cotinine to reveal any subjects who are being untruthful. The difference between quit rates in subjects and controls can then be calculated.
  
  

• Questionnaires to assess efficacy of Repiragene test as a motivator compared with other smoking cessation aids and motivators [ Time Frame: Nine months (from recruitemnt to completion) ] [ Designated as safety issue: No ]
  All subjects will be asked to complete questionnaires (with assistance as needed) to asess the percived value of the Respiragene test compared with other motivators (such as the price of cigarettes, family pressure etc.) and other motivational triggers used in the clinic (salivary ctinine, spirometry results etc.)
  
  

Despite the 5-10% probability of lung cancer in smokers, 50% do not believe they are at significantly increased risk Despite this, over 80% of smokers would like to know their personal risk of lung cancer. RP Young, a clinician at University of Auckland, has show a three way link between biomarkers for COPD, a set of 20 single nucleotide polymorphisms (SNPs) and lung cancer. He has demonstrated a strong correlation between a risk score (derived from FH of cancer, the 20 SNPs & clinical COPD) and the development of lung cancers whereas healthy smokers (who had not developed lung cancer) matched for age, gender and lifetime smoking habits had a relatively low risk score (n=446 lung cancer subjects, 484 healthy current smokers. The odds ratio for lung cancer risk varied from 0.2-3.2 depending on the genetic risk (p<0.001). The Auckland lung cancer risk score has a 90% sensitivity for a score of >4. The validity of 20 SNP gene test has also been confirmed in populations in Barcelona, Spain and Liverpool, UK. The test has been given the trade name "Respiragene".

Small uncontrolled trials of use of Respiragene in smoking cessation clinics in New Zealand and USA show an improvement in smoking cessation at six months after a Respiragene intervention with quit rates of 30-35%. The trial hypothesis is that smokers who have the Respiragene test and a full explanation of their risk score will have a better quit rate at 4 weeks and at six months (after completion of their eight weekly smoking cessation clinic sessions) than controls. Smoking cessation at the six month follow up will bw confirmed by testing for salivary cotinine. Based on data from Young's small trial, we also hypothesise that this uplift of quit rate will be seen for subjects with both high risk scores and average risk scores (there is no low risk category for smokers). These hypotheses are the basis of the primary end points.

The investigators will also be administering the same questionnaire to each subject and control twice, at 4 weeks and six months (after the smoking cessation course) that is primarily designed to evaluate the impact of the Respitagene test in relation to other influences:

• other components of the smoking cessation clinic sessions (salivary cotinine testing, carbon monoxide breath analyser, general clinic help and advice, clinic fact sheets)
• general environmental factors (cost of cigarettes, family pressure, work regulations, doctor's advice)

The results will be analysed using SPSS Statistics 17.0 computer programme.