Background: An association between ocular adnexal MALT lymphoma (OAL) and Chlamydia psittaci (Cp) infection has been proposed, and recent reports suggest that doxycycline treatment causes tumor regression in patients with Cp-related OAL. The effectiveness of doxycycline treatment in Cp-negative OAL has not been tested.
Methods: In a prospective trial, 27 OAL patients (15 newly diagnosed and 12 having experienced relapse) were given a 3-week course of doxycycline therapy. Objective lymphoma response was assessed by computerized tomography scans or magnetic resonance imaging at 1, 3, and 6 months after the conclusion of therapy and every 6 months during follow-up. Cp infection in patients was determined by touchdown enzyme time-release polymerase chain reaction (TETR-PCR). Statistical tests were two-sided.
Results: Eleven patients were Cp DNA-positive and 16 were Cp DNA negative. Doxycycline was well tolerated. At a median follow-up of 14 months, lymphoma regression was complete in six patients, and a partial response (> or = 50% reduction of all measurable lesions) was observed in seven patients (overall response rate [complete and partial responses] = 48%). Lymphoma regression was observed in both Cp DNA-positive patients (seven of 11 experienced regression) and Cp DNA-negative patients (six of 16 experienced regression) (64% versus 38%; P = .25, Fisher's exact test). The three patients with regional lymphadenopathies and three of the five patients with bilateral disease achieved objective response. In relapsed patients, response was observed both in previously irradiated and nonirradiated patients. The 2-year failure-free survival rate among the doxycycline-treated patients was 66% (95% confidence interval = 54 to 78), and 20 of the 27 patients were progression free.
Conclusions: Doxycycline is a fast, safe, and active therapy for Cp DNA-positive OAL that was effective even in patients with multiple failures involving previously irradiated areas or regional lymphadenopathies. The responses observed in PCR-negative OAL may suggest a need for development of more sensitive methods for Cp detection and investigation of the potential role of other doxycycline-sensitive bacteria.