Abstract P4-07-28: Prognostic Impact of Delaying Multimodality Treatment in HER2 Positive Breast Cancer
Authors: Chang Helena , Gornbein Jeffrey , Lim Sin Yee 
Published: March 2023

Objective: Multimodality treatment in breast cancer is a key to the improved survival outcomes. The effects of delays in multimodality treatment in HER2 amplified breast cancer were studied. Patients and Methods: Of the patients with primary HER2 amplified breast cancer who were treated between 2009 and 2018 in a single institution, 1,075 patients met the inclusion criteria. The patterns of the multimodality treatments and the prognostic effects of treatment delays were studied. Kaplan-Meier method was used to estimate the relapse free survival (RFS) and overall survival (OS). Hazard ratio (HR), their 95% confidence interval (CI) and p value were computed using the Cox proportional-hazards model adjusting for 11 covariates including age, ethnicity, clinical T stage, clinical N stage, ER, PR, Ki67, LVI, histologic grade, surgery type (mastectomy versus lumpectomy), neoadjuvant versus adjuvant chemotherapy. The Harrell’s C statistics were used to determine the Cox model accuracy. Adjusted multivariate analyses of recurrence/death and death were computed using Cox proportional-hazards model. Delays in treatment were defined as starting treatment beyond 60 days after diagnosis or after the completion of the leading treatment. Results: Of the patients included, 49% received neoadjuvant chemotherapy/HER2 target treatment and surgery, 43% had adjuvant treatments and surgery and 8% had surgery only without chemotherapy. Timely commencement of treatment in the 3 groups were 85.7%, 72.1% and 78.4% respectively. The 5-year RFS was 88.7% and OS was 98.2%. Patients who received neoadjuvant and adjuvant chemotherapy were combined, and six treatment groups with delays in various treatments were compared: no delay in chemotherapy/target treatment and surgery (1); surgery delay (2); chemotherapy delay (3); delays in both treatments (4) and surgery only groups with (5) or without delays (6). Concordance statistics showed that the covariate adjusted Cox proportional-hazards model had a better accuracy than the unadjusted. Compared to those without delays, patients with both chemotherapy and surgery delayed had worse recurrence/death (adjusted HR = 4.11, 95% CI: 1.39-12.5, p= 0.0161). Delays in either surgery or chemotherapy also increased recurrence/death, although to a lesser magnitude. The adjusted death in surgery delay, chemotherapy delay and delays in both had HR 2.91; 2.22; and 2.29 respectively when compared to the group without delays in either treatment although not significant at p &lt; 0.05. Adjusted recurrence/death and death were similar between neoadjuvant and adjuvant groups (HR 0.99 & HR 0.85 respectively). The group that received surgery only without chemotherapy was associated with worse recurrence/death (adjusted HR=1.78, 95% CI: 0.19 – 16.9) Conclusion: Delays in any treatment adversely impacted recurrence and death and chemotherapy/target treatment is a critical component in treating patients with operable HER2 positive breast cancer.

Citation Format: Helena Chang, Jeffrey Gornbein, Sin Yee Lim. Prognostic Impact of Delaying Multimodality Treatment in HER2 Positive Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-28.