Abstract 4099: Doctor

Abstract

Abstract Colorectal cancer (CRC) is the second most common internal cancer in Australia and the second leading cause of cancer death with > 4,400 deaths in 2007 [1]. Currently there are greater than 14,000 newly diagnosed cases annually in Australia with direct costs of over $2 billion per annum [1]. Worldwide, there is an annual incidence of almost a million CRC cases with an annual mortality around 600,000 [2]. Unfortunately, 30-50% of patients have occult or overt metastases at presentation and once tumours have metastasised prognosis is very poor with a five year survival of less than 10% [3]. By contrast, greater than 90% of patients who present while the tumour is still localised (Dukes' stage A) will still be alive after 5 years and can be considered cured. The early detection of CRC and clinically significant pre-cancerous lesions (adenomas) would therefore significantly reduce the health burden of this disease [3]. Currently the only widely used non-invasive screening test for CRC is the faecal occult blood test (FOBT). Even though screening with FOBT has been shown to lead to reductions in CRC incidence and mortality, there are significant issues that limit its effectiveness as a diagnostic screening tool, such as a poor positive predictive value of 5.3% for suspected cancer and low participation rate of approximately 35% as seen in the Australian National Bowel Cancer Screening Program. To overcome some of the limitations of the FOBT, we believe that a blood test may increase participation rates and could provide a useful adjunct to FOBT In our recent studies we screened over 65 candidate CRC biomarkers using both commercially sourced ELISA kits and reagents developed in-house, in more than 550 CRC patients and controls that were collected with strict SOP based on the EDRN and HuPO. Using logistic regression, we have defined a panel of 3 blood-borne protein biomarkers that differentiates between CRC and normal patient sera with 95% specificity and 75% sensitivity in a single measurement (c.f. FOBT: sensitivity 65.8%, specificity 95% [4]). Currently we are prospectively collecting a new cohort of over 1,000 blood samples from volunteers that have undergone colonoscopy, that include CRC patients , controls and other pathologies (IBD, other cancers etc) to specifically determine the performance of this blood test in asymptomatic and surveillance screening populations. 1. Australian Institute for Health and Welfare and Australasian Association of Cancer Registries 2010. Cancer in Australia: an overview, 2010. Cancer series no. 60. Cat. No. CAN 56. Canberra: AIHW. 2. Weitz, J., et al., Colorectal cancer. Lancet, 2005. 365(9454): p. 153-65 3. Etzioni, R., et al., The case for early detection. Nat Rev Cancer, 2003. 3(4): p. 243-52. 4. Morikawa, T., et al., A comparison of the immunochemical fecal occult blood test and total colonoscopy in the asymptomatic population. Gastroenterology, 2005. 129(2): p. 422-8. Note: This abstract was not presented at the meeting. Citation Format: Leah J. Cosgrove, Kim Fung, Ilka Priebe, Leanne Purins, Bruce Tabor, Mike Buckley, Celine Pompeia, Gemma Brierley, Edouard Nice, Tim Adams, Peter Gibbs, Jeanne Tie, Andrew Ruszkiewicz, James Moore, Trevor Lockett, Tony Burgess. Doctor. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4099. doi:10.1158/1538-7445.AM2014-4099