Recurrence Score Testing Does not Appear to Benefit Patients With Grade 1, Progesterone Receptor-Positive Breast Cancers: An Opportunity to Eliminate Overtreatment and Decrease Testing Costs.

BACKGROUND

We previously described a risk prediction model (Anne Arundel Medical Center [AAMC] model) based on pathology which may eliminate the need for recurrence score (RS) testing in select early-stage breast cancers. There is a concern that patients in discordant risk prediction groups (AAMC vs. RS) may be overtreated or undertreated if RS testing were omitted.

METHODS

We queried the Surveillance, Epidemiology, and End Results (SEER) database for all breast cancer patients between 2004 and 2015. AAMC low-risk was defined as Grade 1 and progesterone receptor-positive (PR + ) tumors, while AAMC high-risk was defined as Grade 3 or estrogen-negative tumors. RS low-risk group was defined as RS < 16 and age ≤ 50 years, or RS ≤ 25 and age > 50 years. RS high-risk group was defined as RS > 25.

RESULTS

A total of 71,212 cases were analyzed. Of these, 590 were AAMC low-risk/RS high-risk discordant, while 5,596 were AAMC high-risk/RS low-risk discordant. For AAMC low-risk/RS high-risk discordant, 10-year breast cancer-specific survival (BCSS) did not differ for patients who received adjuvant chemotherapy versus those who did not (93% chemotherapy vs. 99% unknown/no chemotherapy, p = .12). Overall survival (OS) was also comparable (92% chemotherapy vs. 91% unknown/no chemotherapy, p = .42). In the AAMC high-risk/RS low-risk discordant group, 10-year BCSS (92% chemotherapy vs. 96% unknown/no chemotherapy, p = .06) and OS (87% chemotherapy vs. 90% unknown/no chemotherapy, p = .52) did not differ between adjuvant chemotherapy and unknown/no chemotherapy groups.

CONCLUSIONS

Adjuvant chemotherapy in the AAMC low-risk/RS high-risk and AAMC high-risk/RS low-risk discordant groups did not improve survival. This supports consideration of omission of RS testing in Grade 1, PR + tumors. Patients with Grade 3 tumors do benefit from RS testing.