Writing in the journal Breast Cancer Research and Treatment, Glück and colleagues compared the findings of molecular subtyping to those of traditional clinical pathology to determine breast cancer type, which is used to help guide treatment.
“Molecular subtyping of early-stage breast cancer with the MammaPrint and BluePrint tests identifies a group of patients who do not benefit from neoadjuvant (preoperative) chemotherapy,” said Glück, who is also a member of Sylvester’s Braman Family Breast Cancer Institute.
The study, “Molecular subtyping of early-stage breast cancer identifies a group of patients who do not benefit from neoadjuvant chemotherapy,” was published online in June, ahead of the journal’s print edition.
Analyzing data from four clinical trials with a total of 437 patients, researchers found a group of 90 women (21 percent) who showed little if any benefit from chemotherapy and who had good outcomes five years after surgery. That group could not be identified using the methods of traditional clinical pathology.
This group represented a molecular subtype, Luminal A, identified by the BluePrint and MammaPrint assays, which help physicians identify genetic pathways and guide treatment of breast cancer.
The most significant study finding was that one-fifth of the patients fell into the Luminal A molecular subtype. They showed no benefit from chemotherapy and had a five-year metastases-free survival rate of 93 percent, the highest rate of any group in the study.
“Molecular subtyping shows the potential of precision medicine in early breast cancer therapy,” Glück said. “In this study, the advantages of molecular subtyping allowed us to identify both patients who could avoid chemotherapy prior to surgery, and those for whom chemotherapy provides a benefit.”
“The identification of (the Luminal A) group could lead to improved treatment,” the researchers wrote, “with patients being able to avoid chemotherapy and to receive preoperative and adjuvant endocrine therapy alone.”
Adjuvant therapy is delivered after breast cancer surgery. Breast cancer subtyping has been found to improve the selection of breast cancer patients for both adjuvant and neoadjuvant therapy, which is delivered prior to surgery to reduce tumor size.
The retrospective study was performed on samples from patients enrolled in four independent neoadjuvant chemotherapy clinical trials: 144 patients from the I-SPY 1 trial; 131 patients and 99 patients from two biomarker discovery trials at the University of Texas M.D. Anderson Cancer Center; and 63 patients from the City of Hope National Medical Center.
The MammaPrint, BluePrint and TargetPrint tests of surgically removed tumor tissue are part of the Symphony panel of tests, made by Agendia, Inc.
University of Miami