Clinical outcome of low-grade NHL patients with bone marrow involvement

Background: Bone marrow (BM) involvement in low-grade non-Hodgkin's lymphoma (NHL) has a clear impact on patients' survival. The standard practice is morphological examination of BM biopsy at diagnosis. The clinical significance of flow cytometry (FC) analysis of BM aspirates is largely unknown. Materials and methods: The medical charts of 70 low-grade NHL patients, who underwent BM biopsy and FC analysis between 1994 and 2004, were reviewed. Results: Forty-three patients (61.4%) were BM+ by morphology, while in those without morphological involvement by lymphoma FC was positive in 9 (BM-FC+, 12.9%) and negative in 18 (BM-FC-, 25.7%). The median treatment-free period was shorter in the BM+ and BM-FC+ groups compared with the BM-FC- group (1 and 4 months vs. 31 months, respectively) (log-rank test, P = 0.0195). The median survival time was not reached for the BM-FC- patients, whereas for BM+ and BM-FC+ patients it was 129 and 89 months, respectively, with no significant difference between them [the difference between the BM-FC- and the two other groups was statistically significant (log-rank test, P = 0.029)]. Conclusions: The outcome of low grade NHL in patients who had BM involvement by FC alone or by morphology was similar. If confirmed, these findings suggest a modification in the workup and management of localized low grade NHL.