CSP (Comprehensive Support Project)



Randomized phase III study of adjuvant endocrine-therapy with or without chemotherapy for postmenopausal breast cancer patients who responded to neoadjuvant letrozole

Study design

This is a multicenter study with two-staged (preoperative and postoperative) enrollment and intervention. This include an open-label, randomized, parallel-group controlled study involving patients responding to neoadjuvant endocrine therapy.

Trial schema

Trial schema


  1. To evaluate whether adjuvant chemotherapy is required or not in patients who respond to neoadjuvant endocrine therapy with letrozole. This is accomplished by comparing disease-free survival between 2 groups randomly assigned to treatment.
  2. To overall scheme of this study is designed to assess the impact of neoadjuvant endocrine therapy on long-term outcomes. Disease-free survival and overall survival will be evaluated according to the clinical response (CR/PR/SD/PD) to neoadjuvant endocrine therapy in the primarily enrolled patients.
  3. To explore the clinical and pathological response of neoadjuvant endocrine therapy and the relation to additional beneficial effects of chemotherapy.
  4. To evaluate HRQOL and cost-effectiveness (cost utility).

Primary endpoint: Disease-free survival (DFS)

Secondary endpoints: Overall survival (OS), clinical response rate to neoadjuvant letrozole, pathological response to neoadjuvant letrozole, breast-conserving surgery rate, DFS and OS according to patients with CR/PR/SD/PD after neoadjuvant letrozole, safety, HRQOL, and cost-effectiveness (cost utility)

Scheduled number of patients and study period

Planned sample size: A total of 1700 patients (850 per group).
Enrollment: from May 2008 through May 2013.
Follow-up: 5 years after enrollment of the last patient.

Clinical trial registration

Registered trial number: UMIN 000001090

Presentations at medical conferences

Study design
March 2009: 11th St. Gallen International Breast Cancer Conference,
Poster: P174

Medical papers

Iwata H. Neoadjuvant endocrine therapy for postmenopausal patients with hormone receptor-positive early breast cancer: a new concept. Breast Cancer 18:92-97, 2011

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