In findings that may eventually change the way breast cancer is evaluated and treated, a new study reports that the BluePrint genomic test provides more accurate information about the molecular subtype of a specific breast cancer, compared with the use of conventional IHC-FISH pathology tests.

The prospective observational study of 426 patients was recently published in the Annals of Surgical Oncology (2014; doi:10.1245/s10434-014-3908-y). It concluded that the BluePrint assay may be a better guide than IHC-FISH tests in making decisions about how to treat early stage breast cancer before surgery.

Researchers also reported that the 80-gene BluePrint test reclassified 22% of tumors overall, and it resulted in more accurately identifying breast cancer subtypes than could be done with IHC-FISH testing.

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“This genomic test gives us a better picture of which patients will and [will not] respond to preoperative therapy, and also helps suggest the best course for therapy,” said lead study author Pat Whitworth, MD, a surgical oncologist in Nashville, Tennessee.

The BluePrint test is performed in conjunction with Agendia’s 70-gene MammaPrint test. MammaPrint provides the foundational risk classification of high risk or low risk for breast cancer recurrence, without the ambiguity of intermediate results. Additional therapy-predictive information is then conferred by the 80-gene BluePrint assay, which identifies the molecular subtype.

“One implication of the study findings is that we will eventually end up evaluating and treating many breast cancer patients differently than we do now, because we will rely on their molecular subtype rather than just IHC-FISH pathology results,” Whitworth said.

That would represent a substantial shift in how breast cancer is analyzed and treated, according to Neil Barth, MD, an oncologist and Agendia’s chief medical officer. “Physicians have for nearly 40 years looked to the predictive capabilities of pathology tests such as IHC and FISH to generate clinical decisions,” he said. “But we have also recognized these pathology tests are not complete, as we have often seen discordance between what we were told by IHC-FISH [results] and how the cancer actually behaved.”

Barth said the new study, combined with other recent research, “is telling us that we now have a better tool to measure the dominant biological drivers of each individual breast cancer.” He likened this next iterative step in understanding breast cancer to moving from having a cell phone to having a smart phone. “With molecular subtyping, we now have something akin to a smart phone’s GPS, to help us better determine where we are and where we can go,” he said.

The new study also confirmed published research that preoperative chemotherapy given to patients with the common breast cancer subtype luminal A generally has little benefit.

“The BluePrint test takes a much more nuanced look at breast cancer biology than is available from IHC-FISH tests,” said Whitworth. “This new information about luminal cancers is one example of how molecular subtyping may help guide preoperative treatment decisions.”