Patients with mantle cell lymphoma (MCL) follow a heterogeneous clinical course. While they generally require treatment initiation shortly after diagnosis, it is unclear whether deferring treatment in selected patients with an indolent clinical behavior affects their overall outcome.

In this population-based study, all patients diagnosed with MCL during 1998-2014 were identified in the British Columbia Cancer Agency Lymphoid Cancer Database. The associations between clinico-pathologic characteristics, including the expression of Ki67, SOX11, and TP53, and time to treatment (TtT) and OS were analyzed.

A total of 440 patients with MCL were evaluated: 365 (83%) received early treatment and 75 (17%) were observed ≥3 months. In the observation group, 54 (72%) patients had a nodal presentation, 16 (21%) a non-nodal presentation, and 5 (7%) had only gastrointestinal involvement. Characteristics associated with deferred treatment included good performance status, no B symptoms, low LDH, non-bulky disease, non-blastoid morphology, and lower Ki67 values. The median TtT in the observation group was 35 months (range 5-79), and 60 (80%) patients were observed beyond 12 months. The median OS was significantly longer in the observation group than in the early treatment group (72 versus 52.5 months, respectively, P = 0.041). In multivariable analysis, treatment decision was not associated with OS [HR 0.804 (95% CI 0.529-1.221), P = 0.306].

A subgroup of patients with MCL may be safely observed from diagnosis without negatively impacting their outcomes, including patients with non-nodal presentation as well as asymptomatic patients with low burden nodal presentation and a low proliferative rate.