Carcinoma of an unknown primary site is a common clinical syndrome, accounting for approximately 3% of all oncologic diagnoses. Patients in this group are heterogeneous, having a wide variety of clinical presentations and pathologic findings.
John D. Hainsworth, MD
Recent trials have demonstrated improvements in progression-free and overall survival with the inclusion of the chimeric anti-CD20 monoclonal antibody rituximab (Rituxan) in chemotherapy regimens for treatment-naive and relapsed patients with advanced-stage follicular non-Hodgkin's lymphoma (NHL). As rituximab therapy has significant single-agent activity in follicular NHL, is generally well tolerated, and has no dose-limiting or significant hematologic toxicity, a number of approaches evaluating maintenance therapy with extended dosing of rituximab are being tested. Trials have demonstrated prolonged progression-free survival in patients treated with maintenance rituximab using a variety of schedules following treatment with single-agent rituximab, induction or salvage chemotherapy, or salvage therapy with rituximab and chemotherapy combinations. Small increases in neutropenia and infections have been reported with extended rituximab use. Ongoing trials are evaluating the optimal use of rituximab (maintenance vs retreatment) and the benefit of rituximab maintenance following treatment of therapy-naive patients treated with rituximab-containing chemoimmunotherapy induction regimens. This article discusses the risks and benefits of maintenance rituximab for follicular NHL.
Cancer of unknown primary site represents approximately 3% to 5% of all new cancer diagnoses. Adenocarcinomas account for 60% of all unknown primary cancers and poorly differentiated carcinomas or