Mycobacterium avium-complex (MAC) infection in cancer patients

MAC Infection is seen commonly in AIDS patients but there are few reports in patients with cancer. We reviewed 44 cases of MAC (positive cultures and DNA probes) in cancer patients occurring between 7/94 and 6/96. The mean age was 64 yrs; 22 were male; 33 had solid tumors, 4 lymphoma, 7 AML and 1 CLL. Patients presented with a variety of signs and symptoms however pulmonary symptoms (70%) and upper lobe involvement radiographically (59%) predominated. Pulmonary symptoms (cough, SOB, sputum) 31 Systemic manifestations (weight loss, fever, sweats) 13 Gastrointestinal symptoms (nausea, diarrhea) 3 None of the patients were bacteremic. Radiological features included upper lobe nodular infiltrates (14); upper lobe cavitary lesions (6), upper lobe consolidation (6), bilateral infiltrates (6), and patchy nodular infiltrates (4). The chest x-ray was negative in 8 patients. Twenty two patients were treated withmultidrug regimens including clarithromycin, ciprofloxacin, rifabutin and ethambutol for an average of one year. Among these, 17 responded and 5 experienced early death due to other causes without progression of MAC infection. 12 patients had stable, non-progressive disease, and the decision not to treat them was made. The 10 remaining patients were discharged for therapy or follow-up by their referring physicians. Unlike AIDS, MAC infection in cancer patients presents predominantly with pulmonary involvement, without bacteremia or disseminated disease. Most patients respond to appropriate therapy and some can be managed without specific antimicrobial therapy.