Oncotype DX Potentially Useful in Node-Positive Disease
A study using the Oncotype DX test showed a relationship between Recurrence Score and chances of breast cancer recurrence and survival in women with estrogen receptor-positive breast cancer that traveled to the lymph nodes in and around the armpit (axillary lymph nodes) who were treated with hormonal therapy and chemotherapy.
Researchers in Ohio conducted the retrospective study using data from the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-28 trial. Retrospective studies look at participants’ medical histories or records taken from earlier studies to analyze the outcomes of treatments or methods.
The Oncotype DX genomic test looks at groups of genes in cancer cells and how they grow and respond to treatment. Samples of tissue taken from surgery are analyzed and given a Recurrence Score, a number between zero and 100 that tells doctors how likely it is for an individual’s cancer to recur. A low Recurrence Score (between zero and 18) means a lower chance of the cancer returning; a high Recurrence Score (above 31) means a higher chance.
Oncotype DX is currently only recommended for use in ductal carcinoma in situ (DCIS) and invasive cancer contained to the breast. Multiple studies, including this one, are asking whether Oncotype may also be used for node-positive cancers.
About NSABP B-28
NSABP B-28 tested disease-free survival, the time after treatment ends that a participant has no signs of breast cancer, and overall survival, the length of time from the end of treatment until death from any cause, in 3,060 people treated with two different chemotherapy combinations. In one arm, participants received four cycles of paclitaxel (Taxol) after four cycles of doxorubicin (Adriamycin) and cyclophosphamide (Cytoxan); in the other, participants had four cycles of doxorubicin and cyclophosphamide alone.
Participants had either lumpectomy or mastectomy before the trial, at least one positive axillary lymph node, known hormone sensitivity and were expected to live at least 10 years after diagnosis. Those with hormone-positive cancers received five years of tamoxifen in addition to chemotherapy.
Current Study Design
This retrospective analysis considered tissue samples from the 1,060 participants from NSABP B-28 who had estrogen receptor-positive breast cancer, had at least one positive axillary lymph node and received tamoxifen following either of the chemotherapy treatments. A Recurrence Score was determined using tissue samples from past breast surgery, then compared to the participant’s disease-free and overall survival.
The analysis showed that:
- Low Recurrence Scores were associated with longer 10-year disease-free survival and overall survival (75.8 percent and 90.0 percent), and longer times before a distant recurrence
- High Recurrence Scores were associated with shorter 10-year disease-free survival and overall survival (48.0 percent and 63.0 percent), and shorter times before distant recurrences
Researchers say these relationships add to what is known about risk of recurrence, as predicted by both the number of positive lymph nodes and the biology of the cancer itself.
What This Means For You
These results suggest Oncotype DX may be a useful tool in hormone-sensitive, node-positive breast cancer, but they must first be confirmed in a clinical trial. Some clinical trials, such as RxPONDER (SWOG S1007), are already underway to explore the use of chemotherapy in certain groups of women with low recurrence scores.
Right now, Oncotype remains available only for node-negative, hormone receptor-positive and HER2 negative disease. If you are newly diagnosed, talk with your doctor about accessing the Oncotype DX test through its recommended use or through clinical trials.
Mamounas, Eleftherios P., Tang, Gong, et al: Prognostic impact of 21-gene recurrence score (RS) on disease-free and overall survival of node-positive, ER-positive breast cancer patients (pts.) treated with adjuvant chemotherapy: Results from NSABP B-28. J Clin Oncol (2012) 30. American Society of Clinical Oncology 2012 Breast Cancer Symposium (September 2012).