70-gene signature identifies ultra-low risk of distant recurrence in breast cancer patients

MammaPrint, a signature test that includes 70 genes, appears to accurately identify hormone receptor-positive breast cancer (HR+BC) patients who are at ultra-low risk of distant recurrence, reports a recent study.

The study included 418 patients aged ≥70 years (median age 78 years) who were diagnosed to have invasive HR+BC. Patients underwent MammaPrint assays following standardized protocols, and clinical risk was assessed using the St. Gallen risk classification system. Those who had previously received neoadjuvant treatment were excluded.

MammaPrint classified 50 patients has having ultra-low risk of distant recurrence. Meanwhile, 224 and 114 patients were deemed low and high risk, respectively. St. Gallen, in comparison, also identified 50 patients as having low clinical risk, while 237 and 131 were of intermediate and high risk, respectively.

There was slight discordance between MammaPrint and St. Gallen. Fourteen ultra-low-risk patients were classified as high clinical risk, while 84 patients who were high-risk in MammaPrint were found to have low or intermediate risk by St. Gallen.

Over a median follow-up of 9.2 years, the 10-year distant recurrence rate was only 2 percent in the MammaPrint ultra-low risk group and 17 percent in those deemed high risk by gene signature.

Multivariate analysis adjusted for confounders revealed that being classified as ultra-low-risk reduced the likelihood of distant recurrence by nearly 90 percent as opposed to those deemed high risk (subdistribution hazard ratio, 0.12, 95 percent confidence interval, 0.02–0.85).

Of note, none of the 14 patients that MammaPrint classified as ultra-low-risk, but had high clinical risk in St. Gallen, developed distant recurrence.