Abstract
Pneumocystis pneumonia (PCP) is an opportunistic infection in people with weakened immune systems, such as people with blood disorders, solid cancers, or acquired immunodeficiency syndrome or who are undergoing immunosuppressive drug therapy or treatment with biological medical products. Trimethoprim-sulfamethoxazole (TMP-SMX) is frequently used for prophylaxis of PCP. The dosage and timing of TMP-SMX administration is not clear, although National Comprehensive Cancer Network guidelines suggest the use of TMP-SMX for prophylaxis of PCP in high-risk cancer patients undergoing chemotherapy. We investigated whether the timing of TMP-SMX administration is related to prophylaxis of PCP in patients with malignant lymphoma. The incidence of PCP was 9.9％ (7/71 patients) in patients with malignant lymphoma, 7.5％ (4/53 patients) in patients with B-cell lymphoma, and 16.6％ (3/18 patients) in patients with T-cell lymphoma. Receiver operating characteristic analysis showed that the cut-off level of peripheral blood lymphocytes for TMP-SMX administration was 250 /μL. TMP-SMX administration in seven to eight tablets per week (e.g., one tablet per day or four tablets twice a week) would be appropriate prophylaxis of PCP in high-risk cancer patients undergoing chemotherapy. We suggest that monitoring of peripheral blood lymphocytes is important and that TMP-SMX administration must start before the peripheral blood lymphocyte level reaches < 250 /μL.
