Abstract 17P
Background
With the Katherine study showing overall survival benefit, adjuvant trastuzumab emtansine (T-DM1) is the standard of care if residual disease is present after neoadjuvant chemotherapy in Her-2 + EBC. However less than 1/5th of patients in lower middle income countries can afford to receive T-DM1 despite the availability of generics. The objective of this study was to evaluate if residual cancer burden score could better stratify the risk of recurrence. This would help in choosing more appropriately in resource-limited settings.
Methods
Single institute experience of prospectively collected data from 2021 to 2024. Patients of early breast cancer receiving NACT for Her-2 positive breast cancer for a minimum of 3 months or trastuzumab and completing all chemotherapy in neoadjuvant setting were included. The histopathology included RCB score and class. The patients were prospectively followed up for invasive recurrences.
Results
180 patients of median age 51y (28-83y) followed up for a median duration of 31.4 (5-43) months were analyzed. TCH, AC-TH and TCHP were the regimen used in 129 (72%),23 (13%) and 27 (15%), respectively. 149 (83%) were ≥ T3 and 160 (89%) were ≥cN1. 111(62%) were ER+ and 73(41%) were ER/PR negative. pCR was seen in 43 (39%). Of the 61% with residual, only 27(15%) were able to receive T-DM1 due to affordability. RCB 1, 2, 3 classes were 57 (32%), 79(44%) and 43(24%) respectively. There were 9 (4.37%) invasive recurrences. None with RCB class 1 had recurrence. Two patients had recurrence after pCR: 1 in brain and 1 as pleural metastasis. Five recurrences occurred with RCB 3 and two with RCB 2. Three patients developed recurrence despite adjuvant T-DM1 and all had a RCB of 3.
Conclusions
In our cohort of 180 patients, RCB class 1 (32%) no invasive recurrences consistent with historical data and behaved similar to those having pCR. In resource-constrained situations when there is need to choose between treatments and all patients cannot afford T-DM1, RCB class 1 may probably represent a low-risk subgroup which may not substantially benefit from T-DM1. More data needs to be pooled from such studies to make robust recommendations. DESTINY-05 may further refine treatment in RCB class 3.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.