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Letrozole After Tamoxifen in Treating Women With Breast Cancer

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT00003140
Recruitment Status : Completed
First Posted : January 27, 2003
Last Update Posted : September 19, 2014
Information provided by (Responsible Party):

Study Description
Brief Summary:

RATIONALE: Estrogen can stimulate the growth of breast cancer cells. Hormone therapy using letrozole may fight breast cancer by reducing the production of estrogen.

PURPOSE: This randomized phase III trial is studying letrozole to see how well it works in treating women with breast cancer who have received tamoxifen for at least 5 years.

Condition or disease Intervention/treatment Phase
Breast Cancer Drug: letrozole Other: placebo Phase 3

  Show Detailed Description

Study Design

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 5187 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: A Phase III Randomized Double Blind Study of Letrozole Versus Placebo in Women With Primary Breast Cancer Completing Five or More Years of Adjuvant Tamoxifen
Study Start Date : August 1998
Primary Completion Date : October 2003
Study Completion Date : October 2003

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Breast Cancer
U.S. FDA Resources

Arms and Interventions

Arm Intervention/treatment
Experimental: Arm I
Patients receive oral letrozole once daily.
Drug: letrozole
Given orally
Other Name: Femara
Placebo Comparator: Arm II
Patients receive oral placebo once daily.
Other: placebo
Given orally

Outcome Measures

Primary Outcome Measures :
  1. Disease-free survival [ Time Frame: 5 years ]

Eligibility Criteria

Information from the National Library of Medicine

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Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   No


  • Histologically or cytologically confirmed primary invasive breast carcinoma resected at time of original diagnosis

    • No ductal carcinoma in situ
  • Axillary lymph node negative, positive, or unknown
  • No evidence of metastases
  • No localized or distant breast cancer recurrence
  • Not registered on protocol NCCTG-893052, any other IBCSG protocol, or protocol SWOG-S9623
  • Hormone receptor status:

    • Estrogen or progesterone receptor positive as defined by tumor receptor content at least 10 fmol/mg protein or receptor positive by ERICA or PgRICA
    • Unknown status allowed if effort to determine status has been made by immunocytochemistry
  • No contralateral breast cancer



  • Postmenopausal


  • Female

Menopausal status:

  • Postmenopausal defined by one of the following:

    • Age 50 or over at start of adjuvant tamoxifen
    • Under age 50 and considered postmenopausal by treating physician at start of adjuvant tamoxifen
    • Under age 50 at start of adjuvant tamoxifen and had bilateral oophorectomy (surgical or radiation)
    • Under age 50 and premenopausal at start of adjuvant tamoxifen, but became amenorrheic during tamoxifen and remained amenorrheic for at least 1 year
    • Considered postmenopausal by physician with LH/FSH levels under the treatment center's postmenopausal limits

Performance status:

  • ECOG 0-2

Life expectancy:

  • At least 5 years


  • WBC ≥ 3,000/mm^3 OR
  • Granulocyte count ≥ 1,500/mm^3
  • Platelet count ≥ 100,000/mm^3


  • AST and/or ALT < 2 times upper limit of normal (ULN) (unless imaging examinations have ruled out metastatic disease)
  • Alkaline phosphatase < 2 times ULN (unless imaging examinations have ruled out metastatic disease)


  • Not specified


  • No concurrent medical or psychiatric condition that would preclude study participation
  • No other malignancy within the past 5 years except adequately treated superficial squamous cell or basal cell skin cancer or carcinoma in situ of the cervix
  • Able to swallow study drug
  • Adequate oral intake


Biologic therapy:

  • Not specified


  • Prior adjuvant chemotherapy allowed
  • No concurrent chemotherapy

Endocrine therapy:

  • Completed at least 4.5 but no more than 6 years of adjuvant tamoxifen after resection
  • Completed at least 4.5-6 years of adjuvant aromatase inhibitor as initial therapy or after tamoxifen
  • No more than 3 months since prior adjuvant tamoxifen
  • No concurrent hormone replacement therapy (e.g., megestrol)
  • No concurrent selective estrogen-receptor modulators (e.g., raloxifene or idoxifene)
  • Concurrent intermittent vaginal estrogens (e.g., Estring) allowed if other local measures for intractable vaginal atrophy are insufficient
  • No other concurrent aromatase inhibitors
  • No more than 2 years since prior aromatase inhibitor therapy (re-randomization)


  • Prior radiotherapy allowed


  • See Disease Characteristics


  • At least 1 month since prior investigational drugs
  • Prior treatment on a clinical trial for breast cancer allowed if permission has been obtained from the sponsors of the original study for their patient to participate on MA.17/JMA.17/BIG-97-01
  • No prior placebo on core protocol
  • No concurrent anticancer therapy
  • Concurrent thyroid medication, calcium, vitamin D, and bisphosphonates allowed
Contacts and Locations

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00003140

  Show 57 Study Locations
Sponsors and Collaborators
NCIC Clinical Trials Group
National Cancer Institute (NCI)
North Central Cancer Treatment Group
International Breast Cancer Study Group
Eastern Cooperative Oncology Group
Southwest Oncology Group
Cancer and Leukemia Group B
European Organisation for Research and Treatment of Cancer - EORTC
Study Chair: Paul E. Goss, MD, PhD Massachusetts General Hospital
Study Chair: James N. Ingle, MD Mayo Clinic
Study Chair: Monica Castiglione-Gertsch, MD University Hospital Inselspital, Berne
Study Chair: Nicholas J. Robert, MD Fairfax Northern Virginia Hematology Oncology, PC - Fairfax
Study Chair: Silvana Martino, DO John Wayne Cancer Institute
Study Chair: Hyman B. Muss, MD University of Vermont
Study Chair: Martine J. Piccart-Gebhart, MD, PhD Jules Bordet Institute
More Information

Goss PE, Ingle JN, Martino S, et al.: Outcomes of women who were premenopausal at diagnosis of early stage breast cancer in the NCIC CTG MA17 trial. [Abstract] 32nd Annual San Antonio Breast Cancer Symposium, December 9-13, 2009, San Antonio, Texas. A-13, 2009.
Chapman JW, Meng D, Shepherd L, et al.: Competing causes of death in breast cancer extended adjuvant endocrine therapy: NCIC CTG MA.17. [Abstract] American Society of Clinical Oncology 2007 Breast Cancer Symposium, 7-8 September 2007, San Francisco, California A-56, 2007.
Goss P: Breaking the 5-year barrier: results from the MA.17 extended adjuvant trial in women who have completed adjuvant tamoxifen treatment. [Abstract] European Journal of Cancer Supplements 4 (9): 10-5, 2006.
Ingle J, Tu D, Shepherd L, et al.: NCIC CTG MA.17: intent to treat analysis (ITT) of randomized patients after a median follow-up of 54 months. [Abstract] J Clin Oncol 24 (Suppl 18): A-549, 2006.
Moy B, Tu D, Shepherd LE, et al.: NCIC CTG MA.17: tolerability of letrozole among ethnic minority women. [Abstract] J Clin Oncol 24 (Suppl 18): A-6018, 305s, 2006.
Pater JL, Tu D, Ingle JN, et al.: An evaluation of the early termination (ET) of MA.17 extended adjuvant therapy trial. [Abstract] Breast Cancer Res Treat 100 (Suppl 1): A-2081, S107-8, 2006.
Robert NJ, Goss PE, Ingle JN, et al.: Updated analysis of NCIC CTG MA.17 (letrozole vs. placebo to letrozole vs placebo) post unblinding. [Abstract] J Clin Oncol 24 (Suppl 18): A-550, 2006.
Abetz L, Barghout V, Thomas S, et al.: Letrozole did not worsen quality of life relative to placebo in post-menopausal women with early breast cancer: results from the US subjects of the MA-17 study. [Abstract] Breast Cancer Research and Treatment 94 (Suppl 1): A-2047, 2005.
Goss PE, Ingle JN, Palmer MJ, et al.: Updated analysis of NCIC CTG MA.17 (letrozole vs. placebo to letrozole vs placebo) post unblinding. [Abstract] Breast Cancer Research and Treatment 94 (Suppl 1): A-16, 2005.
Goss PE, Ingle JN, Tu D: NCIC CTG MA17: disease free survival according to estrogen receptor and progesterone receptor status of the primary tumor. [Abstract] Breast Cancer Research and Treatment 94 (Suppl 1): A-2042, 2005.
Ingle JN, Goss PE, Tu D: Analysis of duration of letrozole extended adjuvant therapy as measured by hazard ratios of disease recurrence over time for patients on NCIC CTG MA.17. [Abstract] Breast Cancer Research and Treatment 94 (Suppl 1): A-17, 2005.
Luk C, Goss P, Pritchard K, et al.: Determinants of preferences for starting extended adjuvant letrozole (L) in postmenopausal women following five years of tamoxifen. [Abstract] J Clin Oncol 23 (Suppl 16): A-642, 39s, 2005.
Vachon CM, Ingle JN, Scott CG, et al.: Pilot study of changes in mammographic density in women treated with letrozole or placebo on NCIC CTG MA17. [Abstract] Breast Cancer Research and Treatment 94 (Suppl 1): A-6005, 2005.
Goss PE, Ingle JN, Martino S, et al.: Updated analysis of the NCIC CTG MA.17 randomized placebo (P) controlled trial of letrozole (L) after five years of tamoxifen in postmenopausal women with early stage breast cancer. [Abstract] J Clin Oncol 22 (Suppl 14): A-847, 88s, 2004.
Whelan T, Goss P, Ingle J, et al.: Assessment of quality of life (QOL) in MA.17, a randomized placebo-controlled trial of letrozole in postmenopausal women following five years of tamoxifen. [Abstract] J Clin Oncol 22 (Suppl 14): A-517, 7s, 2004.

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: NCIC Clinical Trials Group
ClinicalTrials.gov Identifier: NCT00003140     History of Changes
Other Study ID Numbers: MA17
U10CA025224 ( U.S. NIH Grant/Contract )
CAN-NCIC-MA17 ( Registry Identifier: PDQ )
CDR0000065921 ( Other Identifier: PDQ )
First Posted: January 27, 2003    Key Record Dates
Last Update Posted: September 19, 2014
Last Verified: March 2012

Keywords provided by Canadian Cancer Trials Group ( NCIC Clinical Trials Group ):
stage I breast cancer
stage II breast cancer
stage IIIA breast cancer

Additional relevant MeSH terms:
Breast Neoplasms
Neoplasms by Site
Breast Diseases
Skin Diseases
Antineoplastic Agents
Aromatase Inhibitors
Steroid Synthesis Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Estrogen Antagonists
Hormone Antagonists
Hormones, Hormone Substitutes, and Hormone Antagonists
Physiological Effects of Drugs
Antineoplastic Agents, Hormonal
Selective Estrogen Receptor Modulators
Estrogen Receptor Modulators
Bone Density Conservation Agents