Low-risk tumors exhibit high proliferation index

Pathologists at the Yale University School of Medicine in New Haven, Conn., studied the relationship between the Oncotype Dx recurrence score and the cell cycle-related antigen Ki-67 in 32 breast carcinomas and evaluated for a potential association.

Previous studies have shown that patients with a high-risk recurrence score will most likely benefit from adjuvant chemotherapy, but there is no proven advantage for patients with a low-risk recurrence score, who still face an average recurrence risk of 7%, according to the investigators (Int J Surg Pathol 174:303-310, 2009).

Comparison of the recurrence score with tumor type, grade, and the Ki-67 proliferation index (PI) revealed an overall concordance. However, some tumors with a low recurrence score revealed a surprisingly high Ki-67 PI. These cases may correspond to the 7% of low-risk carcinomas that recur, they wrote, and proposed that a combined evaluation of the recurrence score and Ki-67 PI be used to identify tumors with high recurrence potential from the low-risk and intermediate-risk groups.