Background Recognized prognostic factors associated with increased risk of recurrence in patients (pts) with HR+, HER2- early breast cancer (EBC) are higher histologic grade, larger primary tumor size, and greater lymph node involvement. Genomic assays like Oncotype DX obtain prognostic information to indicate benefit of adjuvant therapy. The objective was to examine use of genomic assays and describe demographic, clinical, and pathological characteristics of pts tested.

Methods Real-world data was drawn from the Adelphi EBC I Disease Specific Programme, a cross-sectional observational study in France, Germany, Italy, Spain, United Kingdom (UK), United States (US) and Japan. 765 consulting physicians were surveyed, including questions on use of genomic assays to assess risk of recurrence. In each country, 20-64 of the physicians also completed patient record forms from Mar-Sep 2019 for up to 8 eligible pts with HR+, HER2- EBC.

Results Physicians in US (n=176), UK (n=52) and Spain (n=100) reported highest use of genomic assays to categorize patients from low to intermediate risk (US 61%; Spain 57%; UK 65%) and from intermediate to high risk of recurrence (US 64%; Spain 67%; UK 65%). Lowest use was in Japan (n=134), 13% and 20%, respectively. Oncotype DX was consistently reported as the most frequently used genomic assay to assess the risk of recurrence (see table). Patient record forms were completed for 2447 pts (98% female, mean age 59.6 years, SD 13.0). Frequency of Oncotype DX testing varied by stage, with less testing in stage III pts (stage I 26% (194/755); stage II 20% (221/1130); stage III 11% (56/505) p<0.0001). Similar patterns were seen across most countries, but often not statistically significant. Germany had similar use across stages (~20%). Oncotype DX testing was less frequent in pts with grade 3 tumors (grade 1 21% (100/484); grade 2 22% (203/908); grade 3 12% (44/384); p<0.0001). Similar patterns were seen across countries except UK and Spain where testing was less in pts with grade 1 tumor, but not statistically significant. Oncotype DX testing was less frequent in large tumors (size <2cm 19% (161/865); size 2-5cm 20% (254/1265); size >5 cm 11% (11/105); p=0.0503). Similar patterns were seen across countries except Italy, but generally not significant. Oncotype Dx testing was less frequent in pts >50 years (age ≤50 25% (161/657); age >50 18% (318/1790); p=0.0003). Similar patterns were seen across countries, and significant in Germany (p=0.0029) and Italy (p<0.0001), except for US and Japan where testing was very similar between age groups. Oncotype DX testing was less frequent in node +ve pts, 14% of 733 pts, compared with 23% of 1593 node -ve patients (p<0.0001). Similar patterns were seen in most countries, with some statistically significant differences. Germany and Japan were exceptions, Oncotype DX testing was used for node +ve pts more than node -ve pts. Difference was statistically significant in Japan (p=0.032).

Conclusion Use of genomic assays to assess pt risk of recurrence varied across countries. The most commonly used assay was Oncotype DX. Oncotype DX testing was less frequent amongst stage III, grade 3, large, node +ve tumors or age >50, although there were some important country variations. These data contribute to the understanding of drivers in adopting multi-gene assays within clinical practice.

Genomic AssayTotal(n=729)*US (n=171)Japan (n=122)France (n=93)Germany (n=97)Italy (n=96)Spain (n=100)UK (n=50)
Oncotype DX 67% 91% 45% 54% 64% 60% 63% 94% 
Adjuvant! Online 30% 23% 25% 29% 29% 34% 43% 42% 
Mammaprint 29% 37% 30% 17% 24% 21% 52% 0% 
Breast Cancer Index 17% 29% 25% 13% 14% 17% 2% 4% 
EndoPredict 13% 8% 20% 20% 12% 11% 8% 18% 
Prosigna 11% 8% 11% 22% 4% 6% 21% 8% 
Genomic AssayTotal(n=729)*US (n=171)Japan (n=122)France (n=93)Germany (n=97)Italy (n=96)Spain (n=100)UK (n=50)
Oncotype DX 67% 91% 45% 54% 64% 60% 63% 94% 
Adjuvant! Online 30% 23% 25% 29% 29% 34% 43% 42% 
Mammaprint 29% 37% 30% 17% 24% 21% 52% 0% 
Breast Cancer Index 17% 29% 25% 13% 14% 17% 2% 4% 
EndoPredict 13% 8% 20% 20% 12% 11% 8% 18% 
Prosigna 11% 8% 11% 22% 4% 6% 21% 8% 

*729/765 physicians who assessed all or some of their patients with EBC for risk of recurrence

Citation Format: Jacqueline Brown, Rhys Williams, Alex Rider, Rosie Wild, Michael Method. Multi-country study of the use of genomic assays in HR+, HER2- early breast cancer and characteristics of patients tested [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS4-34.