Abstract 11P
Background
The aim of this study was to evaluate real-world use of ODX RS in early breast cancer (BC) pN0/N1 patients and its impact on adjuvant CT decisions.
Methods
LISE is an ongoing observational study comprehensively evaluating BC characteristics, management practices and outcomes in 3,122 patients diagnosed between January 2010 and December 2021 at Courlancy Cancer Institute (Reims, France).
Results
Among 1,160 eligible HR+/HER2- patients from an interim analysis (N=1,626), ODX testing was performed in 231 patients (19.9%). Pathological tumor size distribution was as follows: pT1a 0.9%, pT1b 12.8%, pT1c 58.0%, pT2 27.9%, pT3-4 0.5%. 78.4% of cases were pN0, 8.6% were pN1mic and 13.0% pN1. Scarff-Bloom-Richardson (SBR) grading was as follows: SBR I 16.0%, SBR II 68.5%, SBR III 15.5%. Luminal A and Luminal B HER2- subtypes accounted for 31.1% and 68.8% of cases, respectively. Multivariate analysis revealed highest ODX use in pT1c or pT2 tumors, with Ki-67 ≥20% and SBR I-II grading. RS distribution and its impact on adjuvant CT decisions are reported in the table. Table: 11P
| ODX testing impact on adjuvant CT decisions | ||||||||||
| ODX RS Distribution a | Before RS | After RS | % change b | |||||||
| No CT benefit | Minimal CT benefit | Potential CT benefit | Substantial CT benefit | HT | HT±CT c | HT+CT | HT | HT+CT | ||
| ODX performed n=231 | 66.7% | 6.1% | 10.8% | 16.5% | 29.7% | 60.7% | 9.6% | 79.0% | 21.0% | -70.0% |
| pN0 n=181 78.4% | 71.3% | 7.9% | 3.4% | 17.4% | 27.8% | 65.7% | 6.5% | 77.5% | 22.5% | -69.4% |
| pN1mic – N1 n=50 21.6% | No CT benefit | Potential CT benefit | Substantial CT benefit | 34.7% | 44.9% | 20.4% | 84.0% | 16.0% | -75.4% | |
| 50.0% | 38.0% | 12.0% |
CT: chemotherapy, HT: hormonotherapy, ODX: Oncotype DX, RS: recurrence score.
aCut-offs were based on criteria from TAILORx and RxPONDER studies.
bReduction in CT indication.
cUndecided due to discordant or intermediate histoprognostic factors.
Conclusions
ODX testing demonstrated major changes in therapeutic choices. In pN0 and pN1mic-N1 patients, CT indication was decreased by 69.4% and 75.4%, respectively. Our real-world clinical practice results describe the ‘grey area’ population requiring ODX prescription and confirm the utility of ODX to guide management and avoid overtreatment.
Legal entity responsible for the study
Bruno Cutuli, Institut du Cancer Courlancy, Reims, France.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.