Abstract P5-18-17: Impact of compliance with National Comprehensive Cancer Network guidelines on adjuvant trastuzumab administration for patients with HER2-positive breast cancer.
Authors: Mullins DN , Maly J , Abdel-Rasoul M , Shapiro CL , Olson EM 
Published: August 2014

Background: The National Comprehensive Cancer Network (NCCN) breast cancer guidelines recommend trastuzumab as a component of adjuvant therapy for patients with stage I-III HER2-positive breast cancer. Reasons for noncompliance with adjuvant trastuzumab therapy and the impact of noncompliance with national guidelines are unknown.

Methods: We retrospectively identified 331 patients with stage I-III HER2 -positive breast cancer treated at the Ohio State University James Cancer Hospital 2005–2011 who were eligible for adjuvant trastuzumab. Medical records were reviewed to obtain age at diagnosis, race, co-morbidity score, stage, hormone positivity, type of therapy administered, date of disease recurrence, vital status and date of last follow up. Available clinician-documented reasons for not administering adjuvant trastuzumab were also recorded. Multivariate logistic regression modeling was used to examine the effect of these variables on completion of 1 year of adjuvant trastuzumab. Cox regression modeling was used to estimate the effect of completing 1 year of trastuzumab on disease-free and overall survival, respectively.

Results: Median follow up was 39.9 months (range 12.0–85.1). Of the 331 patients, the majority of (289; 87%) received at least 1 dose of trastuzumab while 251 (76%) patients completed the recommended 1 year of trastuzumab therapy. In multivariate modeling, age ≥ 70 years (Odds Ratio 0.18, 95% CI 0.07 to 0.47; p &lt; 0.0001) and stage I disease (Odds Ratio 0.34, 95% CI 0.18 to 0.63; p = 0.001) were significant predictors of failure to receive 1 year of adjuvant trastuzumab. Race, hormone status and co-morbidity score were not predictors for completing 1 year of adjuvant trastuzumab. Of the 80 patients who did not complete 1 year of trastuzumab, clinician-documented reasons for noncompliance were available for all women. Reasons cited by treating physicians for either not initiating or completing 1 year of trastuzumab included small tumor size (24; 30%), baseline cardiac dysfunction (19; 24%), medication toxicity (4; 5%), patient refusal (13; 16%), advanced age (5; 6%), development of metastatic disease during adjuvant therapy (5; 6%) or other (10; 13%). Patients who did not complete 1 year of adjuvant trastuzumab had a significantly increased risk of death (HR 6.67; 95% CI 2.72 to 16.36; p &lt; 0.0001) and risk of disease recurrence (HR 3.74; 95% CI 1.88 to 7.46; p &lt; 0.0001) after adjusting for age, stage and co-morbidity score.

Conclusion: Age ≥ 70 years and stage I disease are predictors of noncompliance with NCCN guidelines recommending administration of adjuvant trastuzumab therapy for one year. Failure to complete one year of adjuvant trastuzumab is significantly associated with disease recurrence and worse overall survival in patients with stage I-III HER2-amplified breast cancer.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-18-17.