A multi-gene test for sufferers with early breast cancer that recognizes who can be spared chemotherapy and will continue to be alive and disease-free for 5 years following diagnosis conducted well in a trial.
This is according to the recent outcomes of the West German Study Group (WSG) phase III Plan B trial, provided at the 10th European Breast Cancer Conference (EBCC-10) in Amsterdam, the Netherlands, March 9-11, 2016.
The researchers identified that 94% of early breast cancer sufferers whose score on the 21-gene Recurrence Score (RS) test revealed them to be at minimal risk of disease recurrence, were disease-free following 5 years.
The study is the first to use the multi-gene test to report 5-year survival in sufferers whose breast cancer satisfies the following conditions:
- Cancer has not propagated to lymph nodes (node negative) or has only passed on to 1-3 lymph nodes (node-positive early stage).
- Cancer is HR+ or HER2 negative.
HR+ indicates the breast cancer is hormone receptor positive, showing the cancer cells have high numbers of receptors for estrogen (ER) or progesterone (PR) on their surfaces, enabling the hormones to drive cancer development.
HER2 negative indicates the breast cancer cells do not have great numbers of epidermal growth factor receptors and so will not react to therapy with trastuzumab (Herceptin) and other treatments that focus on HER2.
The 21-gene RS test examines 21 genes that can impact the growth of cancer and how it reacts to therapy. The test outcome is a number from 0-100.
94% of low gene-risk sufferers alive and disease-free at 5 years
For the study, the researchers described a 21-gene RS score of 11 and under as showing the cancer was at minimal risk of recurrence. This choice was made regardless of other clinical indicators – like as lymph node status, tumor size, grade, and patient age – indicating otherwise.
In 2009-2011, the trial registered 3,198 sufferers of median age 56, all of whom went through the gene test. 348 sufferers (15.3%) had a 21-gene RS score of 11 and under – they went through therapy with only anti-hormonal therapy ; they did not get chemotherapy also.
All the other sufferers went through therapy that did include chemotherapy. These sufferers were classified as either medium or high risk (RS score over 25) and were randomized to obtain one of two kinds of chemotherapy: six cycles of docetaxel/cyclophosphamide or four cycles of epirubicin/cyclophosphamide followed by four cycles of docetaxel.
After an average follow-up of 55 months, the researchers identified that 94% of sufferers in the hormonal-treatment only group (the ones whose gene test forecasted they had a minimal risk of recurrence), were still alive and disease-free five years after diagnosis.
Of the greater risk sufferers who obtained chemotherapy along with hormonal therapy, those categorized as medium-risk sufferers also demonstrated a 94% disease-free survival 5 years after diagnosis, while for the high-risk sufferers, this figure was 84%.
Dr. Oleg Gluz, The German Research coordinator, who is based in Mönchengladbach, says:
“In this prospective trial for sufferers who had a clinically-identified intermediate or great risk of recurrence and who had 0-3 lymph nodes included, we have been able to identify around 15% who were evaluated by the 21-gene RS as being at minimal genomic risk.
We were, therefore, able to treat them by anti-hormonal treatment alone and to spare them chemotherapy. The 94% disease-free survival rate that we notice following 5 years without adjuvant chemotherapy is an outstanding outcome.”
The team identified the 21-gene RS test was a much better predictor of breast cancer recurrence than other more standard clinical prognostic measures – like node status, tumor size, grade and presence of Ki67 protein (an indicator of cell proliferation).
‘Strong prognostic effect’:
Dr. Gluz says, the 21-gene RS test will take 8-10 days as the tumor sample has to be sent to a central lab for analysis. The test is simple to carry out, but the expenses are not covered in all nations. However, he notices that various studies recommend it saves money due to the fact it allows therapy to be tailored to people and minimizes the use of chemotherapy.
Dr. Gluz says the RS test provided “additional and independent prognostic details beyond that of established and significant clinical prognostic markers,” and concludes:
“Our data certainly show a stronger prognostic effect of RS in comparison to immunohistochemical tools, like Ki67 and hormone receptor expression, and thus, support the incorporation of the RS test, in combo with nodal status, grade, and tumor size, into routine clinical practice for making therapy choices for these sufferers.”
The study will carry on following up sufferers for up to 10 years. A follow-up trial – WSG-ADAPT – has currently registered over 4,000 sufferers to examine the use of the RS test with the evaluation of early reaction to short-term pre-surgery anti-hormone therapy.
Dr. Gluz anticipates merging both tools could spare around 50-60% of early breast cancer sufferers the requirement to undergo chemotherapy. He and his colleagues assume final survival outcomes from this research to be presented in 2021.