Abstract P5-18-01: A randomized clinical trial of postoperative adjuvant therapy for elderly breast cancer patients: Conditions of obtaining informed consent and reasons for declining participation
Authors: Sagara Y , Sawaki M , Taira N , Saito T , Kashiwaba M , Iwata H , Kobayashi K , Nakayama T , Bando H , Mizuno T , Yamamoto Y , Tsuneizumi M , Takahashi M , Yamaguchi M , Kawashima H , Takashima T , Uemura Y , Hozumi Y , Sagawa N , Mukai H , Ohashi Y 
Published: May 2016

Background: There are few randomized clinical trials examining adjuvant treatment in elderly breast cancer patients. While obtaining informed consent is essential for participation in clinical studies, there is little information on the frequency of agreement to participate among elderly patients. Furthermore, elderly patients might have specific reasons to decline participation.

Patients and Method: The National Surgical Adjuvant Study of Breast Cancer 07 (N-SAS BC 07) is a randomized clinical trial in women over 70 years with HER2-positive primary breast cancer. The primary aim was to investigate the benefit of trastuzumab monotherapy compared with the combination of trastuzumab and chemotherapy. Key inclusion criteria were as follows: women between 70 and 80 years old with HER2-positive breast cancer; underwent curative operation; stage I to IIIA; with sufficient organ function. Patients were randomized to receive either trastuzumab plus chemotherapy or trastuzumab monotherapy. The primary endpoint was disease-free survival, and the secondary endpoints were overall survival, relapse-free survival, safety, health-related quality of life, and cost effectiveness (NCT01104935). It was not possible to predict the number of patients who would agree to participate. In order to comprehensively assess the effect of postoperative adjuvant therapy, we evaluated the reasons why eligible patients declined to participate. The patients were registered in a cohort study to prospectively evaluate the subsequent treatment options and prognosis (07-Cohort). This study examined the obtaining of informed consent for N-SAS BC 07 and the reasons for declining participation, and compared the clinicopathological backgrounds between the N-SAS BC 07 and 07-Cohort groups.

Results: 398 eligible patients have been recruited. Informed consent to participate in N-SAS BC 07 has been obtained from 275 patients (69%) and 123 patients (31%) who declined to participate in the RCT have been registered in the 07-Cohort. The common reasons to decline participation in the RCT were "cannot choose the treatment option (55%)", "refused chemotherapy (16%)", "wanted chemotherapy (9%)", "anxious about clinical studies (9%)" and "family opposition (8%)". The mean ages of the patients in N-SAS BC 07 and 07-Cohort were 73.9 and 74.6 years old, respectively. There were no differences in stage, surgical procedure, lymph node metastasis, or co-morbidities between the groups. ER-positive rate was higher in 07-Cohort group compared with N-SAS BC 07 group (53% vs. 37%, p=0.017, χ2 test).

Conclusion: While we expected the number of registrants to be small, since N-SAS BC 07 investigated whether elderly patients with HER2-positive breast cancer should undergo chemotherapy, almost 70% of the patients accepted informed consent. The most common reason to decline participation in N-SAS BC 07 was "cannot choose the treatment option" and the majority refused chemotherapy. Furthermore, ER-positivity was higher in the 07-Cohort group, which suggested that ER expression in the patients with HER2-positive breast cancer might influence their decision to participate in the study or to choose the treatment option.

Citation Format: Sagara Y, Sawaki M, Taira N, Saito T, Kashiwaba M, Iwata H, Kobayashi K, Nakayama T, Bando H, Mizuno T, Yamamoto Y, Tsuneizumi M, Takahashi M, Yamaguchi M, Kawashima H, Takashima T, Uemura Y, Hozumi Y, Sagawa N, Mukai H, Ohashi Y. A randomized clinical trial of postoperative adjuvant therapy for elderly breast cancer patients: Conditions of obtaining informed consent and reasons for declining participation. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-18-01.