Phil B.FontanarosaMD, Interim CoeditorIndividualAuthorMargaret A.WinkerMD, Deputy EditorIndividualAuthorStephenLurieMD PhD, Fishbein FellowIndividualAuthor
To the Editor: Two patients with advanced breast
cancer who were receiving long-term and stable anticoagulation therapy with
warfarin developed extreme hypoprothrombinemia when treated with trastuzumab
A 75-year-old woman with locally advanced breast cancer diagnosed in
1989 was treated with chemotherapy, mastectomy, radiation therapy, and long-term
hormonal suppression. The patient developed deep venous thrombosis and pulmonary
embolism in 1990, and was treated with heparin and subsequently with warfarin.
International normalized ratios (INRs) ranged from 2.1 to 2.8 while taking
warfarin sodium 5 mg and 7.5 mg on alternate days. In 1995, receptor-positive
progressive cancer was treated sequentially with medroxyprogesterone acetate,
anastrozole, paclitaxel, and doxorubicin.
Nissenblatt MJ, Karp GI. Bleeding Risk With Trastuzumab (Herceptin) Treatment. JAMA. 1999;282(24):2299-2301. doi:10-1001/pubs.JAMA-ISSN-0098-7484-282-24-jbk1222