Women with early-stage breast cancer and an intermediate risk recurrence score from a 21-gene expression assay may be able to avoid chemotherapy, according to a retrospective study published in Cancer.
“Through years of research discoveries, it became clear that we were overtreating many women with breast cancer, especially those with early-stage breast cancer,” Carlos H. Barcenas, MD, assistant professor of breast medical oncology at The University of Texas MD Anderson Cancer Center, said in a press release. “In addition to chemotherapy’s obvious side effects, there were also long-term complications for these women as survivors.”
Carlos H. Barcenas
Historically, women with stage I and stage II breast cancer have been treated aggressively with chemotherapy. However, a 2015 international clinical trial called TAILORx demonstrated that women with hormone receptor–positive, HER-2–negative, lymph node–negative early-stage disease could omit chemotherapy if they had 21-gene recurrence score (Oncotype DX, Genomic Health) of 0 to 10.
Barcenas and colleagues evaluated whether women with this type of breast cancer and an intermediate recurrence score of 11 to 25, who were treated with endocrine therapy, also could abstain from chemotherapy.
“This study evolved out of my patients’ frustration that I could not provide a definitive answer to their paramount question: ‘Do I need chemotherapy?’” Barcenas said. “We decided to look at [MD Anderson Cancer Center’s] own experience to glean insight on how best to care for these women with an intermediate-risk recurrence score.”
Researchers collected data from 1,424 women (median age 56 years; 72.8% white) diagnosed with hormone receptor–positive, HER-2–negative, lymph node–negative breast cancer between 2005 and 2011. The researchers charted the patients’ invasive DFS, RFS, distant RFS and OS.
In total, 297 women had a recurrence score of 0 to 10, of whom 1.7% received chemotherapy; 894 had a recurrence score of 11 to 25, of whom 15% received chemotherapy; and 233 had a recurrence score greater than 25, of whom 73.4% received chemotherapy.
Women in the recurrence score 11 to 25 group who received chemotherapy tended to be younger and have larger and more stage II tumors than those who did not receive chemotherapy.
At a median follow-up of 58 months, women with a recurrence score of 11 to 25 achieved a 5-year invasive DFS rate of 92.6% (95% CI, 89.6-94.7), which was comparable between women who received chemotherapy and those who did not (89% vs. 93%).
Similarly, women who received chemotherapy and those who did not achieved comparable 5-year RFS (95% vs. 96%), distant RFS (96% vs. 96%) and OS (98% vs. 98%).
The effect of chemotherapy demonstrated HRs of 1.64 (95%, 0.73-3.71) for invasive DFS, 1.46 (95% CI, 0.41-5.23) for RFS, 1.25 (95% CI, 0.32-4.91) for distant RFS and 2.19 (95% CI, 0.44-11) for OS.
Barcenas and colleagues noted a relatively short follow-up of 58 months and the low number of women who underwent chemotherapy in the intermediate-risk recurrence score group as limitations of the study and indicated their findings should not be considered practice-changing.
“Our research is likely the most comprehensive data we will have about this patient population until the international randomized trial is published,” Barcenas said. “Hopefully, our findings will serve as a discussion point between physicians and patients as they are making critical decisions regarding a woman’s breast cancer care.” – by Chuck Gormley
Disclosure: An MD Anderson Cancer Center grant from NCI funded this study. One researcher reports an advisory role with Agendia, which markets the MammaPrint assay.