Abstract PS13-40: Real-world outcomes in patients receiving neo-adjuvant chemotherapy for early-stage breast cancer

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Abstract Background: Real-world data on characteristics, outcomes, and toxicity in patients with early breast cancer (EBC) receiving neo-adjuvant chemotherapy (NACT) is lacking. This study characterises experience of NACT in a single UK NHS specialist oncology centre. Methods: Retrospective case note review of sequential patients with EBC treated with NACT between April 2013 and Sept 2019. Treatment regimens, toxicity data, pathological response (PathCR, defined as no residual invasive tumour in the breast and lymph nodes), recurrence-free survival (RFS) and overall survival (OS) were compared between groups according to baseline characteristics and tumour subtype, defined by oestrogen receptor (ER) and HER2 status. Results: 405 patients (median age 52 years (IQR 45–61)) were included with a median follow up of 36.4 months. At diagnosis most (253 (62%)) were symptomatic, 368 (91%) had invasive ductal carcinoma, 19 (5%) invasive lobular carcinoma and 18 (4%) inflammatory, spindle or mixed histology. Most were pre-NACT stage 2 or above (Stage 1 - 12 (3%), Stage 2a - 129 (32%), Stage 2b 148 (37%), Stage 3a - 73 (18%), Stage 3b – 25 (6%), Stage 3c -14 (3%)) with no clear trend in stage by year of diagnosis or disease subtype and overall 244 (60%) were node positive pre-NACT. 99% had grade 2 or grade 3 cancer; 320 patients (79%) had Ki-67 >15% and 72 patients (18%) had Ki-67 <15%. 392 (96.8%) patients received primary prophylaxis with Granulocyte-Colony Stimulating Factor (GCSF) and 327 patients (76.9%) received an anthracycline-taxane (AT) containing schedule. There were few dose delays due to toxicity (no delay 353 (87%) v delay 51 (13%)) however, 187 (46%) had one or more dose reductions which was significantly more common in patients >61 years (Odds Ratio (OR) v patients <45 years 1.32, 95% (CI 1.10-1.58,P=0.003). PathCR rates did not significantly vary by year of treatment, tumour size or nodal stage but did vary by subtype: ER+/HER2- 8/128 (6.25%), ER+/HER2+ 34/111 (30.6%), ER-/HER2+ 42/69 (60.9%), ER-/HER2- 32/97 (33%). PathCR was predictive of RFS: recurrence occurred in ER+/HER2- pathCR 0/8 (0%) v non-pathCR 24/120 (20%), ER+/HER2+ 0/34 (0%) v 7/77 (9.1%), ER-/HER2+ 4/42 (9.5%) v 6/27 (22%) and ER-/HER2- 4/32 (12.5%) v 21/65 (32%). There was a non-significant trend towards improved pathCR with the addition of platinum (P) to AT in ER-/HER2- disease (19/43 (44.2%) v 11/41 (26.8%) respectively, OR 2.16 (95% CI 0.86-5.40, p=0.09). In HER2+ disease, the addition of pertuzumab (P) to trastuzumab (H) with AT chemotherapy did not increase pathCR rates. At time of analysis 10% of patients had died precluding meaningful analysis of OS by response. Ki-67, Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) had no significant associations with pathCR. Conclusions: Real-world outcomes from NACT at a single UK centre are consistent with published randomised data for pathCR rates by tumour subtype. Despite 96.8% of patients receiving GCSF almost half had at least one dose reduction, potentially compromising dose intensity. Whilst this retrospective analysis must be interpreted with caution, as expected there was a trend toward improved response with the addition of platinum in ER-/HER2- disease but an interesting lack of further pathCR when adding pertuzumab in HER2 positive disease. Further analyses will be presented including site of recurrence, type of surgery by response, radiotherapy treatment given and multi-variate analysis. Citation Format: Catherine McDonald, Rebecca Squires, Mark Gormley, Ryan Langdon, Ann Archer, Jessica Ball, Georgina Gullick, Chloe Caws, John Boardman, Vivek Mohan, Amit Bahl, Jessica Jenkins, Charles Comins, Lara Gibbs, Jeremy Braybrooke, Timothy Robinson. Real-world outcomes in patients receiving neo-adjuvant chemotherapy for early-stage breast cancer [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 PS13-40.

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