USA. The labelling of AstraZeneca’s tamoxifen (Nolvadex) has been revised to include a boxed warning highlighting the increased risk of uterine malignancies, stroke and pulmonary embolism, and the Warnings section has been extended. AstraZeneca has issued a ‘Dear Doctor’ letter advising that the prescribing information now includes a new boxed warning. The warning contains new information of particular relevance to women with ductal carcinoma in situ (DCIS) and women at high risk for developing breast cancer who are receiving or considering tamoxifen therapy to reduce their risk of developing invasive breast cancer. It states that serious and life-threatening events associated with tamoxifen in this risk reduction setting include uterine malignancies, stroke and pulmonary embolism, some of which may be fatal. Estimated incidence rates for the events are also presented. The Warnings section advises that, while most uterine malignancies seen in association with tamoxifen are adenocarcinomas of the endometrium, uterine sarcoma, the diagnosis of which is generally associated with a poorer prognosis and shorter survival time, has been reported to occur more frequently in long-term tamoxifen users than in non-users; some of these malignancies have been fatal. Patients with prior or present exposure to tamoxifen should be advised to undergo annual gynaecological examinations and to report any gynaecological abnormalities to their physician immediately. Healthcare providers are advised to discuss the potential benefits and risks of tamoxifen therapy with patients, particularly women with DCIS and those at high risk for developing breast cancer who are considering taking tamoxifen to reduce their risk. However, it is also stated that in women already diagnosed with breast cancer, the benefits of tamoxifen therapy far outweigh the risks.

Reference:

‘Dear Doctor’ letter from AstraZeneca, 15 May 2002. Available from URL: http://www.fda.gov/medwatch/SAFETY/2002/may02.htm