Abstract P2-14-14: Adjuvant chemotherapy treatment refusal not associated with increased mortality
Authors: Malmgren Judith , Struckel Robinette , Atwood Mary , Kaplan Henry 
Published: March 2020

Background: Chemotherapy treatment refusal is a constant over time in oncology practice.

Methods: We reviewed patients in our registry cohort from 1990-2015 with first primary surgically treated invasive TNM 7 stage I-III breast cancer recommended for chemotherapy treatment (chemotx) (N= 5488 given, N= 217 refused (3.8%)). Presentation and diagnostic characteristics were analyzed for association with chemotherapy refusal using Pearson chi squares. Logistic regression analysis was used to evaluate patient characteristics association with chemotherapy treatment refusal as the outcome of interest (risk ratio = RR) and Cox proportional hazards modelling for association of chemotx refusal with breast cancer specific survival.

Results: Adjuvant chemotherapy refusal did not decline over time and was constant at an average of 3.8% per year over 25 years from 1990 to 2015. Percentage of chemotx refusers increased with increasing age from 1.4% for age 20-39, age 40-49 (2.6%), age 50-59 (3.6%), age 60-69 (5.0%), age 70-79 (12.4%) and to 13.5% among patients age 80 and above (chi square = 98.67, p&lt;.001). Chemotx refusal was highest among hormone receptor (HR) positive patients (4.2%) vs. HR- (2.6%) (p&lt;.010). After 1998, chemotx refusal was highest among HR+/HER-2- patients (4.8%) and lowest among HER-2+ patients (1.6%). 20% of HR+ chemotx refusers also refused hormone treatment (p&lt;.001). Chemotx refusers were more often stage I (5.5% vs. 3.7% stage II, 2.4% stage III) with refusal decreasing with higher stage (p&lt;.001). After 2015 when recurrence score became available, 7% of HR+/LN- patients tested (N = 388) refused chemotx but only 2% refused hormone treatment. In binary conditional logistic regression modeling order of entry was 1) age, 2) TNM stage, 3) hormone receptor status and 4) diagnosis year. In Cox proportional hazards model adjusted for the regression identified factors, chemotherapy treatment refusal was not associated with increased hazard of breast cancer death.

Conclusions: We observed a direct linear trend of increasing chemotherapy refusal with increasing age and age was the most significant variable in the regression model. Chemotherapy treatment refusal decreased with higher stage breast cancer at diagnosis, hormone receptor negative status and later diagnosis year. Even with a constant treatment refusal rate, mortality was unaffected perhaps related to better prognostic factors among treatment refusers. Better tolerated treatment for older patients and newly developed breast cancer recurrence scores which decrease number of breast cancer patients recommended chemotherapy treatment may help reduce refusals in the future.

Table. Logistic regression model of adjuvant chemotherapy treatment refusal (n=5705)By order of entry into the model:RR (95% CI)p valueAge 20-49reference&lt;.001Age 50-591.72 (1.19, 2.48)Age 60-692.57 (1.73, 3.81)Age 70-797.91 (5.09, 12.31)Age 80+10.09 (4.24, 24.03)TNM 7 stage I3.13 (2.04, 4.81)&lt;.001TNM 7 stage II1.83 (1.22, 2.77)TNM 7 stage IIIreferencehormone receptor status negativereference.001hormone receptor status positive1.87 (1.30, 2.71)Diagnosis year 1990-19981.49 (1.06, 2.09).033Diagnosis year 1999-2004.92 (.64, 1.31)Diagnosis year 2005-2015reference

Citation Format: Judith Malmgren, Robinette Struckel, Mary Atwood, Henry Kaplan. Adjuvant chemotherapy treatment refusal not associated with increased mortality [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-14-14.