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International Breast Cancer Intervention Study II (IBIS-II) (DCIS)

Phase 3
40 Years
70 Years
Open (Enrolling)
Breast Cancer

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Trial Information

International Breast Cancer Intervention Study II (IBIS-II) (DCIS)



- Compare the efficacy of adjuvant tamoxifen vs anastrozole, in terms of local control
and prevention of contralateral disease, in postmenopausal women with locally excised
ductal carcinoma in situ.

- Compare side effect profiles of these drugs in these patients.


- Compare the efficacy of these drugs, according to the receptor status of the primary or
recurrent cancer in these patients.

- Compare the rate of breast cancer recurrence and growth of new contralateral tumors
after cessation of treatment with these drugs in these patients.

- Compare breast cancer mortality in patients treated with these drugs.

- Compare the effect of these drugs on other cancers, cardiovascular disease, fracture
rates, and non-breast cancer deaths in these patients.

- Compare the tolerability and acceptability of side effects experienced by patients
treated with these drugs.

OUTLINE: This is a randomized, double-blind, multicentre study. Patients are stratified
according to participating centre. Patients are randomized to 1 of 2 treatment arms.

- Arm I: Patients receive oral tamoxifen and oral placebo once daily.

- Arm II: Patients receive oral anastrozole and oral placebo once daily. In both arms,
treatment continues for 5 years in the absence of disease recurrence or unacceptable

Patients are followed annually for 5 years and a further 5 years off treatment.

Peer Reviewed and Funded by Cancer Research UK. Sponsored by Queen Mary University of London

ACTUAL ACCRUAL: A total of 2,980 patients were accrued for this study over 9 years.

Inclusion Criteria


- Diagnosis of ductal carcinoma in situ within the past 6 months

- Locally excised with tumor-free margins at least 1 mm

- Hormone receptor status:

- Estrogen or progesterone receptor positive

- Equal to or greater than 5% positive cells



- 40 to 70


- Female

Menopausal status

- Postmenopausal, defined as meeting at least 1 of the following criteria:

- Over age 60

- Prior bilateral oophorectomy

- Age 60 or under with a uterus AND amenorrhea for at least the past 12 months

- Age 60 or under without a uterus AND follicle-stimulating hormone greater than
20 IU/L

Performance status

- Not specified

Life expectancy

- At least 10 years


- Not specified


- Not specified


- Not specified


- No prior deep vein thrombosis

- No prior transient ischemic attack

- No prior cerebrovascular accident


- No prior pulmonary embolism


- No unexplained postmenopausal bleeding

- No other cancer within the past 5 years except nonmelanoma skin cancer or carcinoma
in situ of the cervix

- No other concurrent medical condition that would preclude study therapy, place the
patient at unusual risk, or confound study results

- No evidence of osteoporosis

- Fragility fractures within the spine allowed if T-score level is greater than -4 and
consist of no more than 2 fractures

- Psychologically and physically suitable for 5 years of study therapy


Biologic therapy

- Not specified


- Not specified

Endocrine therapy

- No prior or concurrent tamoxifen use lasting more than 6 months unless treatment was
completed more than 5 years ago. Women in IBIS-I can join if off trial therapy for
at least 5 years.

- No prior or concurrent raloxifene use lasting more than 6 months unless treatment was
completed more than 5 years ago.

- No other prior or concurrent selective estrogen-receptor modulator use lasting more
than 6 months unless treatment was completed more than 5 years ago

- No concurrent systemic estrogen-based hormone replacement therapy, including vaginal
estrogen preparations


- Not specified


- See Disease Characteristics

- No prior mastectomy

- No planned prophylactic mastectomy


- At least 3 months since prior unapproved or experimental agents

- No concurrent anticoagulants

Type of Study:


Study Design:

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Single Group Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Treatment

Outcome Measure:

Development of histologically confirmed breast cancer, both invasive and non-invasive with median follow-up at 5 years

Outcome Time Frame:

2 years

Safety Issue:


Principal Investigator

Jack Cuzick, PhD

Investigator Role:

Study Chair

Investigator Affiliation:

Cancer Prevention Trials Unit, Queen Mary University of London


United Kingdom: Research Ethics Committee

Study ID:




Start Date:

September 2003

Completion Date:

January 2022

Related Keywords:

  • Breast Cancer
  • ductal breast carcinoma in situ
  • breast cancer in situ
  • Breast Neoplasms
  • Carcinoma in Situ
  • Carcinoma, Intraductal, Noninfiltrating