Researchers say the Oncotype DX test may be an effective tool to identify which women with early-stage breast cancer are unlikely to benefit from chemotherapy.
Study leader Dr. Joseph Sparano, of Montefiore Medical Center in New York, NY, and colleagues recently presented their findings at the European Cancer Congress 2015 in Vienna, Austria.
The study assessed the effectiveness of a genetic test called Oncotype DX, created by Genomic Health, Inc.
The test works by searching for the presence of 21 breast cancer-related genes in breast tissue, producing a score that predicts the risk of breast cancer recurrence. Scores range from 0-100, with a higher score indicating a greater risk for recurrence.
Around 2 in 3 breast cancer cases in the US are hormone receptor-positive. Women diagnosed with such cancers normally undergo surgery, followed by treatment with hormone therapy.
Many women with hormone receptor-positive breast cancers also undergo chemotherapy in order to destroy any cancer cells that many have spread beyond the breast and reduce the risk of recurrence. While some of these women may not need chemotherapy, there is currently no effective way of determining which women could safely avoid the treatment.
According to Dr. Sparano and colleagues, previous research has suggested the Oncotype DX test may be an effective way to predict which women with hormone receptor-positive breast cancer could avoid chemotherapy without raising their risk for recurrence. In this latest study, the team set out to further validate these findings.
1% recurrence risk for low-risk women treated with hormone therapy
Using the Oncotype DX test, the researchers found that 16% of the study participants were at low risk for breast cancer recurrence (a score of 10 or less), 67% were at intermediate risk (a score of 11-25), while 17% were at high risk for recurrence (a score of 26 or higher).
Fast facts about breast cancer
- Around 231,840 new cases of invasive breast cancer will be diagnosed in the US this year
- Around 1 in 8 women will develop breast cancer in their lifetime
- There are more than 2.8 million breast cancer survivors in the US.
Women with low-risk breast cancer recurrence were treated with hormone therapy alone, those at intermediate risk received hormone therapy with or without chemotherapy, while women at high risk for recurrence received hormone therapy and chemotherapy.
According to the authors, this is the first clinical trial to treat patients with early-stage breast cancer based on the results of the Oncotype DX test.
While the study is ongoing in order to further evaluate whether chemotherapy is effective for reducing breast cancer recurrence among intermediate- and high-risk groups, independent reviewers of the study recommended the results for the low-risk group be released early.
The team found that around 99% of low-risk women treated with hormone therapy alone did not experience breast cancer recurrence within 5 years. What is more, the rate of invasive disease-free survival at 5 years was almost 94%, while the risk of cancer returning at a distant site was less than 1%.
Based on these findings, the team concludes that most women with early-stage, hormone receptor-positive breast cancer are unlikely to need chemotherapy.
In addition, the researchers believe the Oncotype DX test is an effective tool to determine which patients with early-stage breast cancer are unlikely to benefit from such treatment.
Dr. Sparano adds:
"The compelling results seen in this global study provide unequivocal evidence supporting the clinical utility of Oncotype DX to risk-stratify patients with early-stage breast cancer, and indicate that the findings are generalizable to everyday clinical practice."
Breast cancer survivor Mary Lou Smith, a leader in the Eastern Cooperative Oncology Group (ECOG) and the American College of Radiology Imaging Network (ACRIN) who helped design the study, says the findings offer hope for many women with early-stage breast cancer.
"These findings will give women with early-stage breast cancer greater certainty that anti-estrogen therapy will decrease their risk of recurrence and increase their chance for survival whereas chemotherapy will not," she adds.
Elsewhere on Medical News Today, a new study reveals how media coverage surrounding Angelina Jolie's double mastectomy in 2013 improved public awareness of reconstructive surgery after breast cancer.