1Division of Hematology/Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
2Department of Internal Medicine, Kyung Hee University Hospital, Seoul, Korea.
The median age of the patients included in our analysis was 60 years (range, 22-86 years). Of the patients, 50.9% were male. No occurrence of tuberculosis was encountered during the course of treatment with bortezomib-containing chemotherapy. However, we found 6 patients who developed tuberculosis during the follow-up period after myeloma diagnosis. Of the 6 tuberculosis cases, 4 were documented by acid-fast bacilli culture and 2 by tuberculosis pleurisy with increased adenosine deaminase levels. Of the 6 patients, 3 were previously exposed to bortezomib-containing treatment; the time interval from their last exposure to bortezomib to the tuberculosis diagnosis was from 5 to 21 months (5, 12, and 21 months, respectively). The other 3 patients developed tuberculosis during the course of their treatment with a thalidomide-containing regimen or alkylating agents. They were never exposed to bortezomib before developing tuberculosis. Thus, we found no case of tuberculosis during the course of treatment with a bortezomib-containing regimen in our study, except for the 3 patients who were previously exposed to bortezomib (3/285, 1.1%). The incidence rate of tuberculosis among our patients was lower than that in a recent study (7.0%). Although it cannot be directly compared with that of our study, the higher incidence of tuberculosis in the previous study might be associated with the other drugs combined with bortezomib. In our series, the most commonly combined drug was dexamethasone (57.6%), with 14.9% of the patients receiving bortezomib alone. Only 7.2% of the patients received bortezomib combined with cyclophosphamide or thalidomide. However, the study by Ahn et al.  showed that most patients received bortezomib in combination with thalidomide and cyclophosphamide. Our data imply that the addition of more combination drugs that may affect immune function, such as thalidomide or cyclophosphamide, might increase the patient's susceptibility to tuberculosis. To clarify this finding, a more extensive survey of the incidence of tuberculosis and the various myeloma treatment regimens is required. In conclusion, tuberculosis infection in the patients treated with a bortezomib-containing regimen was not common in our series. The increase in the susceptibility to tuberculosis by bortezomib-containing regimens might be more dependent on the other combination drugs.