[Chemotherapy-Induced Reactivation of Hepatitis B in Recurrent Breast Cancer - A Case Report].

It is known that reactivation of hepatitis B virus (HBV) is an important complication of chemotherapy, and it can cause fatally severe hepatitis in some cases. A 72-year-old woman, underwent radical mastectomy for left breast cancer at the age of 35 years. In January 2008, local recurrence and multiple bone metastases occurred, and chemotherapy was started. S-1(80 mg/day for 28 consecutive days followed by a 14-day rest period)was used as the fourth-line of treatment, but grade 3 anemia(Hb 6.6 g/dL)developed at the end of seventh course. Therefore, blood transfusion was performed. Five months after transfusion, blood tests showed elevated liver function markers and HBs antigen positivity, so post-transfusion hepatitis was suspected. However, it was diagnosed as de novo hepatitis caused by reactivation of HBV from occult infection, as the patient's stored sample before the transfusion tested positive for HBV-DNA. The hepatitis did not become severe, but it was a persistent infection with continued administration of a nucleoside analog. Identifying the reactivation risk and taking appropriate action based on guidelines are necessary for administering chemotherapy safely to patients with occult HBV infection.