Abstract 8P
Background
Anthracycline-sparing (AS) regimens caused less cardiotoxicity and provided equivalent outcomes with anthracycline-containing (AC) regimens in early HER2 positive breast cancer (BC) prospective trials. We would like to confirm these findings in the real-world setting.
Methods
A retrospective review of HER2 positive early BC patients was conducted from Jan 2016 to May 2024 at two tertiary hospitals in Western Australia (WA). Eligible patients had received anti-HER2 targeted therapy with chemotherapy. Data analysed included pathological complete response (pCR), grade 3 or 4 (G3/4) toxicities including cardiotoxicity, hospitalisation rates, and disease-free survival (DFS) computed by Kaplan Meier analysis.
Results
179 patients were included with median ages of 54 (AC) vs 55 (AS) years. Median duration of follow up was 4.5 years. 38/119 (31.9%) patients received AC vs 81/119 (68.1%) AS regimens. Adjuvant AS patients had significantly more N0-1 cancers (97.5% vs 73.7%), P<0.0001. 60/179 (33.5%) patients had neoadjuvant therapy; n=24 (40%) had AC; 36 (60%) had AS regimens. AS group had numerically higher rates of pCR, 55.6% vs 45.8%. The AC group had more G3-4 toxicities (32.3% vs 19.7%); more cardiotoxicities (4.8% vs 2.6%); and hospital admissions (21% versus 12.8%) than the AS group. Patients with non-pCR had a significant drop (-2.9%) in mean ejection fraction (EF) between baseline and pre-operative timepoints, P=0.027 compared to no significant LVEF fall in those experiencing a pCR. 5-year DFS was not significantly different at 96.7% (AC) vs 95.6% (AS), P= 0.56. Table: 8P
| Variable | AC N (%) | AS N (%) | |||||
| All pts | Neoadj | Adjuvant | All pts | Neoadj | Adjuvant | P AC v AS | |
| Total | 62 | 24 | 38 | 117 | 36 | 81 | |
| Age (years) | |||||||
| median | 55.5 | 53.5 | 48 | 58 | |||
| range | 24-78 | 24-78 | 32-75 | 21-85 | 21-82 | 27-85 | |
| Pathological complete response (pCR) | |||||||
| Complete pCR | 11 (45.8) | 20 (55.6) | |||||
| Incomplete pCR | 13 (54.2) | 16 (44.4) | |||||
| Pathological Nodal (N) stage | |||||||
| N0 | 31 | 16 (66.7) | 15 (39.5) | 89 | 27 (75) | 62 (76.5) | P=<0.0001 |
| N1 | 18 | 5 (20.8) | 13 (34.2) | 24 | 7 (19.4) | 17 (21) | |
| N2 | 11 | 3 (12.5) | 8 (21.1) | 2 | 2 (5.6) | 0 (0) | |
| N3 | 2 | 0 (0) | 2 (5.3) | 2 | 0 (0) | 2 (2.5) | |
| Ejection Fraction (EF) | |||||||
| Baseline median % | 66 | 70 | 66 | 67 | |||
| Range | 48-83 | 54-71 | 48-83 | 46-82 | 54-82 | 46-82 | |
| Final median after completion of anti-HER2 therapy % | 60.5 | 63 | 63 | 63 | |||
| Range | 19-75 | 53-70 | 19-75 | 28-79 | 40-73 | 28-79 | |
Conclusions
Current WA practice includes both AC and AS regimens. As expected, AC group had more toxicities and hospital admissions than AS group. Despite lower nodal risk BC the AS group had similar short term BC outcomes. Patients with non-pCR had significant EF reductions prior to surgery. More data is needed to confirm this finding and explore the underlying biology.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
H. H. Lee.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.