Archived – Important Safety Information Regarding Tamoxifen and Incidence of Uterine Malignancies, Stroke and Pulmonary Embolism

Important safety information regarding tamoxifen and incidence of uterine malignancies, stroke and pulmonary embolism

November 7, 2002

To: Hospital Chief of Medical Staff, Oncologists

Please forward to the relevant Departments (Medical Directors; Director, Department of Family Medicine; Director, Department of Pharmacy; Director, Department of Gynecology, Director, Department of Oncology) and involved professional staff and please post this NOTICE in your institution.

Health Canada would like to draw your attention to a recent publication identifying important safety information on the use of tamoxifen and the incidence of uterine malignancies, stroke and pulmonary embolism. This safety information is derived from NSABP P-1 study (National Surgical Adjuvant Breast and Bowel Project Breast Cancer Prevention) with women at high risk for breast cancer or having ductal carcinoma in situ (DCIS) receiving tamoxifen in the prevention setting. It is emphasized that the use of tamoxifen in the prevention setting is not an approved indication in Canada.

For the indications currently approved in Canada "treatment of breast cancer in estrogen receptor positive tumors" (Product Monograph Novaldex-D (tamoxifen citrate), AstraZeneca Canada Inc., date of revision May 2, 2002), the benefits of using tamoxifen have been judged to outweigh the potential risks. This information applies to all tamoxifen containing products, regardless of the manufacturer.

Higher incidences of uterine malignancies, stroke and pulmonary embolism were associated with tamoxifen treatment compared to that of placebo in the patient population of study NSABP P-1. Uterine malignancies were categorized into endometrial adenocarcinomas and uterine sarcomas, and the incidence rates per 1,000 women-years were 2.20 for tamoxifen versus 0.71 for placebo and 0.17 for tamoxifen versus 0.0 for placebo, respectively. For stroke, the incidence rate per 1,000 women-years was 1.43 for tamoxifen versus 1.00 for placebo. For pulmonary embolism, the incidence rate per 1,000 women-years was 0.75 for tamoxifen versus 0.25 for placebo. The median length of follow-up of study NSABP P-1 has reached 6.9 years^{Footnote 1}.

Reporting rates determined on the basis of spontaneously reported post-marketing adverse events are generally presumed to underestimate the risks associated with drug treatments.

The identification, characterization, and management of drug-related adverse events is dependent on the active participation of health care professionals in adverse drug reaction reporting programmes. Health care professionals are asked to report any suspected adverse reactions in patients receiving tamoxifen, to the appropriate manufacturer or to the Marketed Health Products Directorate at the following address:

Any suspected adverse drug reactions can also be reported to: 

Canadian Adverse Drug Reaction Monitoring Program (CADRMP)

Marketed Health Products Directorate

Health Canada

Address Locator: 0201C2

Ottawa, Ontario, K1A 1B9

Tel: (613) 957-0337 or

Fax: (613) 957-0335

Toll free for consumers and health professionals: Tel: 866 234-2345,

Fax: 866 678-6789

cadrmp@hc-sc.gc.ca

The ADR Reporting Form and the ADR Guidelines can be found on the TPD web site or in The Canadian Compendium of Pharmaceuticals and Specialities.

Your professional commitment in this regard has an important role in protecting the well- being of your patients by contributing to early signal detection and informed drug use.

Health Canada asks that you share these recommendations with your staff or membership and encourage their implementation in the interest of patient safety.