Second breast cancer: recurrence score results, clinicopathologic characteristics, adjuvant treatments, and outcomes-exploratory analysis of the Clalit registry

Abstract

Data on using the 21-gene Recurrence Score (RS) testing on second breast cancer (BC; second primary or local recurrence) are lacking. This cohort study examined patients with first and second BC, who underwent 21-gene testing both times. It included a 'study-cohort' (60 N0/N1mi/N1 ER + HER2‒ BC patients with ≥2 RS results >1 year apart) and a 'general 21-gene-tested BC-cohort' (2044 previously described N0/N1mi/N1 patients). The median time between the first and second BC was 5.2 (IQR, 3.1-7.1) years; the second BC was ipsilateral in 68%. Patient/tumor characteristics of the first- and second-BC in the 'study-cohort' were similar, except for the RS which was higher in the second BC (median [IQR]: 23 [17-30] vs 17 [14-22], p < 0.001). Overall, 56 patients had follow-up data, of whom 5 experienced distant recurrence (2 RS 11-25 patients and 3 RS 26-100 patients). Studies exploring the prognostic utility of the RS in this setting are warranted.

Fig. 1. A Box-and-Whiskers plot showing the RS distribution in the first BC in the study cohort vs the RS distribution in the ‘general 21-tested BC cohort’ by nodal status.

The horizontal line represents the median, and the box is drawn from the 1^st to the 3^rd quartile. The upper whisker represents the highest value below the 3^rd quartile plus 1.5 × IQR. The lower whisker represents the lowest value above the 1^st quartile minus 1.5 × IQR. Red x symbols represent datapoints that are beyond the 3^rd quartile plus 3 × IQR. BC breast cancer.

Fig. 2. RS results in the first and second BC.

a RS results in the second versus the first BC for each patient in the study cohort by nodal status. Red markers/lines represent cases where the second RS was higher than the first, blue markers/lines represent cases where the second RS was lower than the first, and green markers/line represent a case with identical RS results in both tests. b A Box-and-Whiskers plot showing the RS distribution in the first vs the second BC by nodal status. The horizontal line represents the median, and the box is drawn from the 1^st to the 3^rd quartile. The upper whisker represents the highest value below the 3^rd quartile plus 1.5 × IQR. The lower whisker represents the lowest value above the 1^st quartile minus 1.5 × IQR. Red circles represent datapoints that are beyond the 3^rd quartile plus 3 × IQR. BC breast cancer.

Fig. 3. KM curves of freedom from distant recurrence for the study cohort by RS category in the second RS result.

The box under the graph presents the number of patients at risk at each time point. One-degree of freedom log-rank p values were calculated from all the data. BC breast cancer, CT chemotherapy, RS Recurrence Score.