Bone marrow histological patterns can predict survival of patients with grade 1 or 2 follicular lymphoma: a study from the Groupe d‘Etude des Lymphomes Folliculaires

Summary The influence of bone marrow biopsy (BMB) histology on prognosis and management of follicular lymphomas (FL) remains controversial. A total of 390 patients with grade 1 or 2 FL were prospectively included in the multicentric Groupe d’Etude des Lymphomes Folliculaires trial and their BMB reviewed in order (i) to quantify the ratio of lymphomatous foci (LFo) area to that of BMB size (LFo/BMB), (ii) to determine the BMB patterns for a practical grading of marrow infiltration, (iii) to assess the intra- and interobserver reproducibility of this grading and (iv) to analyse this grading on event-free (EFS) and overall survival (OS), using univariate and multivariate analyses. A total of 267 patients (68%) had BMB involvement, with inter- and intra-observer reproducibility for classifying the patterns of involvement of 91 and 96%, respectively. Uni- and multivariate analyses demonstrated the adverse influence of (i) a ratio of LFo/BMB ‡0AE1, i.e. three or four nodules/ medullary space or ‡1 nodule + foci of diffuse involvement on EFS (P ¼ 0AE03) and (ii) two different histological patterns in the same BMB on EFS (P ¼ 0AE004) and OS (P ¼ 0AE001). This latter finding was only significant in patients with a high tumour burden and remained significant in multivariate analysis. These results indicate that BMB histology can predict survival of FL patients with a high tumour burden, and may help in defining their treatment.