February 2, 2007

Biomarker May Forecast Probability Of Recurrence In Breast Cancer

Testing tumors for a protein called Ki67 after short-term treatment for breast cancer may help doctors predict whether a patient is likely to have a recurrence, a new study shows.

The presence of Ki67 indicates tumor cell growth, and researchers have used Ki67 measurements as a marker of whether experimental cancer treatments effectively stop cancer growth. To determine whether this marker also indicates a clinical benefit, such as improved recurrence-free survival, Mitch Dowsett, Ph.D., of The Royal Marsden Hospital, in London, and colleagues studied Ki67 levels in tumor biopsy samples taken before and after 2 weeks of presurgical treatment with anastrozole, tamoxifen, or both drugs from 158 women with hormone receptor-positive breast cancer.

The researchers found that higher Ki67 expression after 2 weeks of presurgical therapy was associated with worse recurrence-free survival. There was no association between the Ki67 level before therapy and recurrence-free survival. They also found that larger tumor size before therapy and lower estrogen receptor level after 2 weeks of treatment were associated with worse recurrence-free survival.

"Measurements of tumor Ki67 expression after short-term endocrine treatment may improve the prediction of recurrence-free survival for breast cancer patients," the authors conclude. They add that larger studies are needed to confirm the results before such testing is made widely available to patients.

Contact: Catherine O'Mara, Press & PR Officer, the Royal Marsden NHS Foundation Trust

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