Rapid Fire Session 2014 World Cancer Congress

Genetic test declining and high cancer risk perception in DNA mismatch repair gene mutation families (#462)

Louisa Flander 1 , Antony Ugoni 2 , Louise Keogh 3 , Heather Niven 1 , Alison Rutstein 1 , Aung Ko Win 1 , Driss Ait Ouakrim 1 , Clara Gaff 4 , Ingrid Winship 5 , Mark Jenkins 1
  1. Centre for Epidemiology & Biostatistics, University of Melbourne, Melbourne, VIC, Australia
  2. School of Physiotherapy, University of Melbourne, Melbourne, VIC, Australia
  3. Centre for Women's Health, University of Melbourne, Melbourne, VIC, Australia
  4. Paediatrics, Royal Melbourne Hospital, Melbourne, VIC, Australia
  5. Clinical Genetics, Royal Melbourne Hospital, Melbourne, VIC, Australia

Background: About half of people from mutation-carrying families do not undergo genetic counselling and/or testing to identify their mutation status and risk of colorectal cancer (CRC). 

Aim:We studied perceived CRC risk and qualitative analysis of reasons for declining in this group.

Methods: We studied 26 participants (mean age 43.1 years, 14 women) in the Australasian Colorectal Cancer Family Registry who were relatives of mismatch repair gene mutation carriers; who had not been diagnosed with any cancer at the time of recruitment and who had declined an invitation to attend genetic counselling and/or testing at the time of interview. Bounded estimates of perceived CRC risk over the next 10 years, understanding of genetic testing and CRC risk, reasons for declining testing and self-reported colonoscopy screening were elicited during a face-to-face semi-structured interviews.

Results: A sub-group of decliners (31%) unconditionally rejected genetic testing compared to conditional decliners who would consider genetic testing in the future. Mean perceived 10-year risk of CRC was 54% [95% CI 37, 71] in unconditional decliners, compared with the mean perceived 10-year risk of CRC of 20% [95% CI 5,36] in people who conditionally decline genetic testing. This difference remained after adjusting for potential confounding factors (age, gender and reported screening colonoscopy).

Conclusions:The unconditional decliner group perceive themselves to be at 3.26 times higher risk than conditional decliners. Novel interventions in general practice clinics may improve genetic testing uptake and/or appropriate colonoscopy screening for this high-risk and under-serviced group.