Preemptive use of lamivudine in breast cancer patients carrying hepatitis B virus undergoing cytotoxic chemotherapy: a longitudinal study.

Reactivation of hepatitis B virus (HBV) after cytotoxic chemotherapy is a serious problem, and it occurred to 41% of breast cancer patients carrying HBV. Previous studies have demonstrated that lamivudine was effective for HBV flare-up during cytotoxic chemotherapy. We aimed to monitor the HBV status of breast cancer patients undergoing chemotherapy with preemptive lamivudine over time. Six breast cancer patients carrying hepatitis B surface antigen (HBsAg) were monitored during chemotherapy, five in the adjuvant setting and one with metastatic disease. Preemptive lamivudine was given throughout the chemotherapy course. HBsAg, HBV envelope antigen (HBeAg), anti-HBV envelope antibody (HBe Ab), serial serum alanine transaminase (ALT), quantitative HBV viral DNA analysis, and HBV DNA precore promoter and precore sequence were monitored. One patient carried wild type and the other five precore mutant strain of HBV by examination of HBV sequence in precore promoter and precore region. No evident HBV reactivation developed, and all patients tolerated lamivudine well. During the 6-to-8-month follow-up after cessation of cytotoxic therapy and withdrawal of lamivudine, serum ALT remained unchanged, although an increase of HBV DNA levels in four patients was found. No emergence of the tyrosine-methionine-aspartate-aspartate (YMDD) lamivudine-selective resistant strain was observed in the six patients. Preemptive use of lamivudine can effectively prevent reactivation of HBV in breast cancer patients receiving postoperative adjuvant chemotherapy. Lamivudine can be discontinued safely without emergence of lamivudine-resistant HBV strain or rebound HBV flare-up. The candidate for the use of preemptive lamivudine in HBV carriers who need short-term chemotherapy remained to be investigated