Ultralow MammaPrint Score Means Excellent Breast Cancer Outcomes
People diagnosed with breast cancer who got an ultralow risk of recurrence score on the MammaPrint genomic test had excellent long-term outcomes, whether or not they received hormonal therapy, chemotherapy, or both after surgery, according to the latest analysis from the MINDACT trial.
The research was presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting. Read the abstract of “Outcome of patients with an ultralow risk 70-gene signature in the MINDACT trial.”
About Genomic Tests
Also called genomic assays, genomic tests analyze samples of cancer tumors to see how active certain genes are. The activity level of these genes affects the cancer’s behavior, including how likely it is to grow and spread. Genomic tests help you and your doctor make decisions about whether more treatments after surgery would be beneficial.
Doctors use several genomic tests to analyze breast cancer tumors. The MammaPrint test is one of them.
While their names sound similar, genomic testing and genetic testing are very different.
Genetic testing is done on a sample of your blood, saliva, or other tissue to see if you have a change — also called a mutation — in a gene that is linked to a higher risk of breast cancer.
About the MammaPrint test
The MammaPrint test is a genomic test that analyzes the activity of 70 genes in invasive breast cancers that are:
- stage I, stage II, or operable stage III (meaning the stage III breast cancer can be removed with surgery)
- lymph node–negative or in three or fewer lymph nodes
- up to 5 cm in size
- hormone-receptor-positive or hormone-receptor-negative
MammaPrint results say whether the breast cancer has a high risk or low risk of coming back (recurring) within 10 years of diagnosis. Knowing if the cancer has a high or low risk of recurrence can help you and your doctor make more informed decisions about whether treatments after surgery, such as chemotherapy, are needed to reduce the risk of recurrence.
About the Study
Called the MINDACT (Microarray in Node Negative Disease May Avoid Chemotherapy) trial, this study was started in 2007 to see if the MammaPrint test could accurately estimate the risk of breast cancer recurrence within 10 years of diagnosis. The MammaPrint test performed well and has been on the market since 2005.
This latest analysis looked at the long-term outcomes of people who had what the researchers called an ultralow MammaPrint score, meaning the breast cancer has an ultralow risk of recurrence.
“We wanted to assess the survival outcomes of patients with an ultralow risk tumor biology included in the MINDACT trial and investigate if the identification of an ultralow risk subgroup can help to avoid overtreatment in early-stage breast cancer,” said Josephine Lopes Cardozo, M.D., of the Netherlands Cancer Institute, during her presentation on the analysis.
Of the 6,693 people in the MINDACT trial:
- 1,000 people had an ultralow risk score
- 3,295 people had a low-risk score
- 2,398 had a high-risk score
Among the people with an ultralow risk score:
- 67% were age 50 or older
- 81% were diagnosed with cancers that were smaller than 2 cm
- 80% had no cancer in the lymph nodes, meaning the cancer was lymph node–negative
- 96% were diagnosed with cancers that were grade 1 or grade 2
- 99% were diagnosed with estrogen-receptor-positive breast cancer
- 69% were treated with hormonal therapy after surgery
- 14% were treated with hormonal therapy and chemotherapy after surgery
- 16% received neither hormonal therapy nor chemotherapy after surgery
For the people with an ultralow risk score, the researchers also calculated a clinical risk of recurrence score. Clinical risk of recurrence looks at the characteristics of the cancer, such as:
- tumor size
- number of lymph nodes involved
In general, the larger or higher any of these factors are, the higher the clinical risk of recurrence.
Of the 1,000 people with an ultralow risk score:
- 741 were considered to have a clinical low risk of recurrence
- 259 were considered to have a clinical high risk of recurrence
The researchers looked at the rates of people who had no distant recurrence, meaning the cancer had not come back in a part of the body away from the breast, such as the bones or lungs. Researchers call this distant metastasis–free survival. They also looked at breast cancer–specific survival rates, meaning how many people had not died from breast cancer.
Follow-up was about 9 years.
Overall, for people with an ultralow risk score:
- the 5-year distant metastasis–free survival rate was 98.1%
- the 8-year distant metastasis–free survival rate was 97.0%
- the 8-year breast cancer–specific survival was 99.6%
Specifically, for people with an ultralow risk score and a clinical low-risk of recurrence score:
- the 5-year distant metastasis–free survival rate was 98.7%
- the 8-year distant metastasis–free survival rate was 97.6%
- the 8-year breast cancer–specific survival was 99.7%
For people with an ultralow risk score and a clinical high-risk of recurrence score:
- the 5-year distant metastasis–free survival rate was 96.3%
- the 8-year distant metastasis–free survival rate was 95.0%
- the 8-year breast cancer–specific survival was 99.2%
The researchers also looked to see if 8-year distant metastasis–free survival rates were different for people with an ultralow risk score who had received different treatments after surgery:
- The rate for people who did not receive either hormonal therapy or chemotherapy after surgery was 97.8%.
- The rate for people treated with hormonal therapy after surgery was 97.4%.
- The rate for people treated with hormonal therapy and chemotherapy after surgery was 94.9%.
“In conclusion, patients with an ultralow risk 70-gene signature have an excellent prognosis with 8-year breast cancer–specific survival rates above 99% regardless of clinical risk,” Dr. Cardozo said. “Very few patients developed distant metastases, with 8-year [distant metastasis–free] rates ranging from 95% to 98%. Furthermore, we observed excellent [distant metastasis–free] rates for the 84% of ultralow risk patients who received only endocrine therapy or no adjuvant systemic treatment.
“The clinical implications of this research are that we can confirm that the 70-gene signature can identify patients with an ultralow risk of recurrence and that these patients could be candidates for further de-escalation of treatment thus further reducing overtreatment and the risk of side effects,” she added.