Results from the large CALGB 9581 clinical validation study of the Oncotype DX® colon cancer test confirm that Recurrence Score® (RS) results improve the ability to differentiate high recurrence risk disease from low recurrence risk disease, beyond conventional factors such as T-stage, mismatch repair (MMR) status, nodes examined, grade and lymphovascular invasion. The results of the study were published early online in the Journal of Clinical Oncology.
Stage II colon cancer refers to cancer that extends through the wall of the colon but has not invaded lymph nodes or spread to distant parts of the body. Many patients with this stage of disease have good outcomes with surgery alone, and routine adjuvant (post-surgery) chemotherapy is not currently recommended for Stage II colon cancer. Chemotherapy may, however, be considered for Stage II patients with a higher risk of cancer recurrence.
The Oncotype DX colon cancer test evaluates 12 genes in a sample of tumor tissue and generates a Recurrence Score. The Recurrence Score provides information about the likelihood of cancer recurrence—and as a result, can improve treatment decisions.
Researchers conducted a validation study of the 12-gene recurrence score in tumor specimens from patients enrolled in the Cancer and Leukemia Group B (CALGB) 9581 study. The study included 1,713 patients with stage II colon cancer who were randomly assigned to treatment with the monoclonal antibody edrecolomab or observation. There was no survival difference between the two groups. The current analysis included all patients with available tissue and recurrence (162) and a random selection of patients whose disease did not recur.
A Recurrence Score was assessed in 690 tumor samples. The results indicated that the Recurrence Score result was the strongest predictor of recurrence risk, providing risk discrimination beyond conventional clinical and pathologic measures in multivariable analyses. The Recurrence Score result was particularly valuable in patients with T3 stage and intact (proficient) mismatch repair (MMR) protein function, a population for whom conventional factors are uninformative. In this group of patients, the Recurrence Score result identified 22 percent of patients with an average risk of recurrence at five years above 20 percent. A high colon cancer Recurrence Score result reveals an underlying biology indicative of more aggressive disease for which adjuvant chemotherapy may be more appropriately considered.
The researchers concluded that the 12-gene Recurrence Score predicts recurrence in stage II colon cancer. They note that the Recurrence Score can help physicians identify the most appropriate treatment plan for patients with stage II colon cancer and can potentially spare some patients from chemotherapy that they don’t need.
Venook AP, Niedzwiecki D, Lopatin M, et al. Biologic Determinants of Tumor Recurrence in Stage II Colon Cancer: Validation Study of the 12-Gene Recurrence Score in Cancer and Leukemia Group B (CALGB) 9581. Journal of Clinical Oncology. Published early online March 25, 2013. doi: 10.1200/JCO.2012.45.1096
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