The study reported by Dalerba et al. elegantly showed that lack of CDX2 expression might be a negative prognostic factor in colon cancer. It also showed that lack of CDX2 expression may be predictive of the efficacy of chemotherapy in patients with stage II cancer.
To underscore the power of these findings, we would more carefully consider the role of microsatellite instability and BRAF status. Associations between a lack of CDX2 expression and microsatellite instability and BRAF mutation are known, and the prognostic and predictive implications of those markers have been extensively studied.1-5 Moreover, microsatellite instability is currently a key factor in decision making regarding the treatment of patients with stage II cancer who have undergone radical resection.
In addition, in the study reported by Dalerba et al., a possible bias in patient selection may have limited the findings on the predictive role of CDX2 expression. The available data were not derived from randomized trials comparing adjuvant chemotherapy with surgery alone. Given the association between CDX2 and adverse prognostic features, patients with tumors that lacked CDX2 expression, as compared with patients with CDX2-positive tumors, may have had a more aggressive disease. These aspects could have influenced the decision by treating physicians to withhold adjuvant chemotherapy from patients with poor clinical conditions.
Supplementary Material
Footnotes
No potential conflict of interest relevant to this letter was reported.
Contributor Information
Marta Schirripa, University of Southern California, Los Angeles, Los Angeles, CA
Fotios Loupakis, Istituto Oncologico Veneto IRCCS, Padua, Italy
Heinz-Josef Lenz, University of Southern California, Los Angeles, Los Angeles, CA
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