According to a study published in the journal Clinical Cancer Research, information about gene expression in breast tumors predicts the risk of distant recurrence in women with ten or more positive lymph nodes.

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.

Oncotype DX is a test indicated for patients with newly diagnosed stage I or II, node-negative, estrogen-receptor positive breast cancer who will be treated with tamoxifen. The test evaluates a panel of 21 genes to predict a patient’s ten-year risk of cancer recurrence. The test classifies patients as being at high, intermediate, or low risk of recurrence based on a Recurrence Score. Information about a woman’s risk of recurrence may guide decisions about the need for chemotherapy.

One of the studies that contributed to the development of Oncotype DX involved women with node-positive breast cancer; results of this study are presented in the current report.

The women enrolled in the study were diagnosed with breast cancer between 1979 and 1999 and were followed through 2002. The average tumor size was 4.4 cm and the average number of involved lymph nodes was 15 (range 10-40). Eighty percent of women were treated with chemotherapy and 54% received tamoxifen.

Rate of distant recurrence was significantly linked with the Recurrence Score. The risk of distant recurrence over ten years ranged from 29% among women with the lowest Recurrence Scores to 80% among women with the highest Recurrence Scores.

The researchers conclude that gene expression profiles of tumor samples (some of which were more than 20 years old) provide information about risk of distant recurrence among women with ten or more positive lymph nodes. They note, “New larger studies are needed to more accurately define the relationship between Recurrence Score and likelihood of recurrence in node-positive patients…”

Reference: Cobleigh MA, Tabesh B, Bitterman P et al. Tumor Gene Expression and Prognosis in Breast Cancer Patients with 10 or More Positive Lymph Nodes. Clinical Cancer Research. 2005;11:8623-8631.

Related News:

Medicare Agrees to CoverOncotype DX (1/25/06)

Oncotype DX Predicts Local and Regional Recurrences in Breast Cancer Patients (12/15/05)

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