Cascade colorectal cancer screening guidelines: a global conceptual model.

Background: Guidelines should be a catalyst toward achieving, as a universal standard, the most effective possible care. However, guidelines mainly use evidence of effectiveness as the basis for recommendations. This approach may not be the most appropriate for all healthcare settings because of differing levels of available medical and financial resources. This report from the Guidelines Committee of the World Gastroenterology Organization presents a new conceptual model of cascade colorectal cancer screening guidelines that is also evidence based but resource driven. The emphasis in this variation of the model is on colonoscopy resources at the top of the cascade for a screening goal of prevention by finding and removing the colorectal cancer precursor lesions, the adenoma, as well as early detection. This is a concept study for consideration in the development of future guidelines. Various tests can be reordered within the framework of this model. The cascade concept says, "do what you can with what you have," rather than, "do it this way or no way."

Methods: A systematic review of colorectal cancer screening was performed and an evidence-based cascade (hierarchical recommendations) developed that could apply to healthcare settings having different levels of medical (primarily colonoscopy in this version of the model) resources. A review team representing both developed and developing countries examined published data and provided expert opinion. Cascade guidelines were prepared and reviewed by the team.

Results: A set of 4 resource levels were delineated based on available data: colonoscopy, sigmoidoscopy, different sensitivity fecal occult blood tests, and recommendations for colorectal cancer screening were made based on each level, from high to low resources for average risk men and women. The major resource considered was endoscopic in this version of the model.

Conclusions: Each country, region, or healthcare setting needs to determine whether colorectal cancer screening is a legitimate consideration based on other healthcare priorities. Where there is a major burden of colorectal cancer and sufficient resources to mount a screening program, the cascade colorectal cancer screening guidelines model can assist in decisions regarding screening methods. This version is based mainly on available endoscopic resources. These guidelines are evidence based but resource driven. Each healthcare setting needs to determine its resource level as a basis for selecting the screening approach that is most applicable and therefore most likely to succeed. This concept study provides a model that can be adapted to a variety of evidence-based options with consideration of available resources. Its goal is to enhance colorectal cancer screening worldwide, especially in developing countries where the colorectal cancer incidence and mortality is rising rapidly.