Breast cancer treatment without chemotherapy
A new genetic test avoids chemotherapy, while maintaining high survival rates for women with early stages of hormone-receptor positive breast cancer.
According to the new results obtained during the phase III plan B clinical trial of the German research group, 94% of women who underwent breast cancer therapy, who, according to the results of analysis using the 21-gene recurrence probability scale (21-gene Recurrence Score (RS), Oncotype DX) were in the low-risk group, after 5 years after the analysis, they had no signs of the disease.
In the period from 2009 to 2011, 3,198 patients were included in the study, the median age of which was 56 years. They had diagnoses of early breast cancer with or without lymph node involvement, their tumors were characterized as hormone-receptor positive (HER2-positive) or HER2-negative, in which tumor cells do not have a large number of receptors for epidermal growth factor, which means they are immune to specific drugs such as trastuzumab (herceptin).
The 21-gene relapse probability scale is a test analyzing a group of 21 genes capable of influencing the behavior of malignant cells and their response to treatment. The test results range from 0 to 100 points. In this study, patients who received no more than 11 points were assigned to a low risk group for relapses, even in cases where generally accepted clinical factors, such as the status of lymph node lesions, the stage of development and size of the tumor, as well as age, indicated a potentially high risk.
348 patients (15.3%), who received no more than 11 points, were canceled auxiliary chemotherapy, and they received only antihormonal drugs. All other patients who received more than 11 points, had more than 4 affected lymph nodes or HER2-negative tumors, were assigned to moderate or high risk groups and received a randomly assigned chemotherapy option: six cycles of docetaxel/cyclophosphamide or four cycles of epirubicin/cyclophosphamide, followed by four cycles of docetaxel.
After the end of therapy, the follow-up period for women was approximately 5 years (median 55 months). At the time of the examination, 94% of the participants who were in the low-risk group according to genomic indicators and had undergone only antihormonal therapy were alive and had no signs of the disease. For the moderate-risk group who underwent auxiliary chemotherapy, the 5-year survival rate without signs of the disease was also 94%, while for the high-risk group (more than 25 points on the genomic scale) who also underwent chemotherapy, this indicator was 84%.
Further analysis of other prognostic factors, such as the status of lymph nodes, the size and stage of tumor development, as well as the level of Ki67 protein (a marker of cell proliferation of solid and some hematological malignant tumors), showed that the 21-gene relapse probability scale is the most effective independent prognostic factor of disease recurrence compared to clinical factors or the level of Ki67 protein, both when used separately and in combination with them.
The new test takes 8-10 days to complete, as the tumor tissue samples are sent to the central laboratory for analysis. The results of several studies have shown that its implementation is advisable from a financial point of view, as it allows for more personalized chemotherapy, and in some cases completely abandon it.
The authors plan to extend the observation period for the study participants to 10 years. In addition, more than 4,000 patients have already been included in an additional study aimed at evaluating the effectiveness of the combined use of a 21-gene relapse probability scale with an assessment of an early response to short-term preoperative antihormonal therapy to reduce the level of Ki67 protein. The researchers believe that combining these two tools will avoid additional chemotherapy in about 50-60% of cases of early breast cancer. The final results of the study will be known in 2021.
The results of the work are presented in a report at the 10th European Breast Cancer Conference held on March 9-11 in Amsterdam (O. Gluz et al. 8LBA: Prospective WSG Phase III PlanB trial: Clinical outcome at 5 year follow up and impact of 21 Gene Recurrence Score result, central/local-pathological review of grade, ER, PR and Ki67 in HR+/HER2- high risk node-negative and –positive breast cancer).
Article by Oleg Gluz et al. West German Study Group Phase III PlanB Trial: First Prospective Outcome Data for the 21-Gene Recurrence Score Assay and Concordance of Prognostic Markers by Central and Local Pathology Assessment published in the Journal of Clinical Oncology.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the European CanCer Organization: EBCC-10 NEWS: Five-year results show 21-gene test successfully identifies early breast cancer patients who can be spared chemotherapy.
14.03.2016