Breast cancer and colorectal cancer are leading causes of cancer-related deaths worldwide. The identification of specific tumor characteristics that would allow for an accurate prediction (prognosticators) of disease course and response to treatment would represent an important advancement in the management of these common malignancies. Unfortunately, no currently known disease prognosticators are reliable in predicting clinical course, or identifying the treatment that would be of greatest benefit to an affected individual. Recently the detection in some tumours of HER1 and HER2 proteins - members of the type 1 growth receptor family (T1GFR) - have shown promise for helping predict patient outcomes and in determining which tumors respond best to specific therapies. These proteins have also recently been used as targets for newly developed drugs to treat these cancers. The expression of the entire T1GFR family (HER1, HER2, HER3, and HER4) by breast and colorectal tumors, and their potential usefulness in predicting disease outcome and patient response to specific treatment(s) has not been explored. Dr. Sam Wiseman is evaluating the expression of the entire T1GFR family in a group of 4500 breast cancer and 500 colorectal cancer samples to determine its relationship to patient treatment and outcomes. His study will be carried out utilizing tissue microarrays, a methodology that allows for the rapid evaluation of large numbers of tumors for molecular markers. The results of this study may lead to improved disease prognostication, outcome prediction, and therapy selection for people diagnosed with breast or colorectal cancer.