Abstract P4-10-04: Assessment of clinical trial participation on breast cancer survival

Abstract

Abstract Background Accredited cancer treatment centers offer clinical trials for patients since it is universally accepted that participation in these trials is advantageous. Purpose The purpose of this study was to assess whether clinical trial participation was associated with a survival advantage. Methods We identified 308,291 cases of first primary female invasive breast cancer from the California Cancer Registry 2000-2015. Participation in a clinical trial was documented. Clinical trials were defined as National Cancer Institute (NCI) sponsored studies such as National Surgical Adjuvant Breast and Bowel Project (NSABP) and Southwest Oncology Group (SWOG); pharmaceutical trials; and local investigator initiated studies. The distribution of age, race/ethnicity, socioeconomic status (SES), and stage between clinical trial participants and non-participants was compared using contingency tables and the χ2 Test. Kaplan-Meier Survival Analysis and the Log Rank test were used to compare differences in breast cancer specific survival between participants and non-participants. Cox Regression Analysis was used to estimate the risk of mortality between participants and non-participants after adjusting for age, race/ethnicity, SES, grade, and treatment. Analyses were conducted separately for each stage. Hazard ratios (HR) and 95% confidence intervals (CIs) were reported. Results There were 3,517 (1.1%) patients who participated in a clinical trial. Almost 50% of participants were enrolled in an NCI trial, 38% in a local/investigator initiated study, and 13% were in a trial sponsored by a pharmaceutical company. Trial participation was highest for patients less than 45 years of age (21.9%) and lowest in patients 70 years of age and older (12.3%). Most participants were in stage 2 (44.6%). Participation increased with increasing SES. Only 8.5% of participants were in the lowest SES whereas 35.4% were in the highest SES. Unadjusted survival analysis indicated that there was no survival advantage for stage 1 patients (χ2 = 0.41, p=0.52) whereas study participants in stages 2, 3, and 4 had statistically significantly better survival. Adjusted hazard ratios indicated that stage 2 patients participating in a trial had a 23% reduced risk of mortality (HR=0.77; CI: 0.65 - 0.94). For patients in stage 4, the risk of mortality was reduced by 36% (HR=0.64; CI: 0.47 - 0.87). There was no risk reduction for patients in stages 1 and 3. Conclusion Only a small percent of patients enroll in breast cancer clinical trials and participation is correlated with age and SES. There is a survival advantage for participation in a clinical trial for stages 2 and 4 patients. Citation Format: Parise C, Caggiano V. Assessment of clinical trial participation on breast cancer survival [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-10-04.