A study published in the Journal of the National Cancer Institute reports that gene expression profiling may allow women with grade 2 breast cancer to be reclassified into two groups-one with a lower risk of recurrence and one with a higher risk of recurrence.
The prognosis of women with breast cancer depends on several factors, including the grade of the tumor. Grade refers to how abnormal the tumor cells look under a microscope and how quickly the tumor is likely to grow. A commonly used grading system for breast cancer assigns grades of 1 to 3, with 1 being the least abnormal and 3 being the most abnormal.
Many breast cancers are classified as grade 2, suggesting an intermediate level of risk. For women who fall into this group that is neither low-risk nor high-risk, there continues to be uncertainty about expected risk of cancer recurrence. To explore whether additional information about the tumor could help refine prognosis in women with grade 2 tumors, researchers evaluated the role of gene expression profiling.
Gene expression profiling explores the patterns of genes that are active in tumor cells. Studies suggest that gene expression may provide information about prognosis or likely response to treatment in several types of cancer, including breast cancer.
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In this study, researchers analyzed samples from 597 breast tumors. The researchers first identified gene expression patterns that were linked with grade 1 or grade 3 tumors. When they analyzed gene expression patterns from grade 2 tumors, they found that these tumors displayed a range of patterns-some were more similar to grade 1 tumors and some were more similar to grade 3 tumors.
The researchers found that the gene expression pattern of the grade 2 tumors was linked with risk of recurrence-women with grade 2 tumors that had gene expression similar to grade 1 tumors had a lower risk of recurrence than women with grade 2 tumors that had gene expression similar to grade 3 tumors.
The researchers conclude that gene expression profiling may improve the accuracy of tumor grading in women with breast cancer. Specifically, it may be possible to divide women with grade 2 tumors into groups with lower and higher risks of recurrence.
Reference: Gene Expression Profiling in Breast Cancer: Understanding the Molecular Basis of Histologic Grade To Improve Prognosis. Journal of the National Cancer Institute. 2006;98:262-72.
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