Summary: The effectiveness of screening depends on the underlying biology of cancer. Depending on the growth rates and metastatic potential of the tumor, screening may or may not be effective. Screening is much less effective than we had hoped for aggressive tumors as they can metastasize even when small or grow rapidly and present as interval tumors. For slow growing tumors with very low metastatic potential, early identification will not improve outcome and screening can lead to the identification of additional lesions not destined to become a clinical problem (both invasive and preinvasive lesions), and may be responsible for 20-30% of cancers detected by screening. There are ways that we can improve screening today 1-limit it to the populations who are most likely to have the tumors where early detection makes a difference (The USPSTF guidelines are a good start) 2- work to improve the diagnostic accuracy, especially with mammography (using trained mammographers to interpret images), and minimize biopsy recommendations for very low risk lesion; Use shared decision making to discuss screening, prepare patients for results, and consider prevention interventions as part of the risk assessment process when high risk individuals are identified. 3- use available tools to predict tumor behavior of screen detected tumors, and consider less aggressive interventions as appropriate. We can and must do better- we need to work to identify populations at risk for the most aggressive tumors where screening is less effective, and find better treatment and prevention strategies. It is very important to invest in large scale demonstration projects to better determine risk factors for specific biologic types of cancer, and test less aggressive interventions both for screening and treatment- of low risk tumors.
