Genomic Health, Inc. has announced that the company has initiated an independent clinical validation study for its 18-gene Oncotype DX colon cancer assay. Utilizing more than 1,200 patient samples from the landmark QUASAR trial, the validation study will use prospectively defined endpoints to assess the clinical utility of the Oncotype DX colon cancer assay to predict likelihood of recurrence for stage II colon cancer patients treated with surgery alone and the magnitude of treatment benefit with chemotherapy following surgery. Results from the study are expected to be reported in the second half of 2009. Genomic Health has completed four development studies to identify and select the 18 genes for the Oncotype DX colon cancer assay till date. The validation study is utilizing samples from QUASAR, the largest study of its kind. An international, multicenter trial, QUASAR examined the benefit associated with adjuvant 5FU/LV for patients with stage II colon cancer. The majority of samples for this analysis of the Oncotype DX colon cancer assay are from the UK. Unlike the Oncotype DX breast cancer assay that captures both recurrence and treatment benefit in one Recurrence Score, the prognostic and predictive genes in the colon cancer assay do not overlap. As such, this colon cancer assay was designed to generate both a prognostic Recurrence Score and predictive Treatment Score. Researchers will evaluate the association of the Recurrence Score with recurrence in stage II colon cancer patients treated with surgery alone. They will also evaluate the association of the Treatment Score with the magnitude of chemotherapy benefit in patients treated with adjuvant 5FU/LV chemotherapy.