Dynamics of circulating t(14;18)-positive cells during first-line and subsequent lines of treatment in follicular lymphoma

In follicular lymphoma the t(14;18) might be useful as a tumor marker in predicting the quality of the response to treatment. We investigated whether analyzing numbers of t(14;18)-positive cells in peripheral blood correlated with remission status in individual patients receiving a variety of treatments. Numbers of circulating t(14;18)-positive cells were determined by real-time polymerase chain reaction (PCR) technique. Disease parameters and response to treatment were related to the pre- and post-treatment numbers of circulating t(14;18)-positive cells for 53 follicular lymphoma patients. In these 53 patients, 70 treatment episodes were investigated. A content of more than 328 t(14;18)-positive cells per 75,000 cells prior to therapy correlated with the more advanced stage IV disease (P=0.01), bone marrow involvement (P<0.01), and overt leukemic lymphoma (P=0.04). Therapy episodes that cleared circulation from t(14;18)-positive cells with more than one log resulted in a significantly longer progression-free survival than treatment episodes with less than one log decline (26 versus 12 months, respectively) (P<0.01). After first-line treatment episodes, numbers of circulating t(14;18)-positive cells declined in fairly all cases, irrespective of the clinical response. However, for second or later lines of treatment, declining numbers of lymphoma cells correlated with a clinical remission, whereas increasing numbers of lymphoma cells were associated with clinically stable or progressive disease. From this, we conclude that quantitation of circulating t(14;18)-positive cells in peripheral blood is of only limited clinical significance in predicting treatment efficacy for the individual follicular lymphoma patient.