Post-treatment PET-CT Findings may Predict the Prognosis of DLBCL with a Bulky Mass

We retrospectively analyzed the prognosis of patients with diffuse large B cell lymphoma (DLBCL) and a bulky mass at diagnosis. We retrospectively analyzed clinical data for 29 consecutive DLBCL patients with an initial bulky mass receiving R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) therapy from 2004 to 2011. Bulky disease was defined as a measurable tumor mass >10 cm in diameter or a mediastinal mass >1/3 of the chest diameter. Patients with primary mediastinal large B-cell lymphoma were excluded. The median age was 65 years (20-78 years) and the maximum tumor diameter was 11.5 cm (10.0-17.0 cm). Complete response and partial response were achieved in 14 patients each, while 1 patient had progressive disease. The 3-year overall survival (OS) rate and progression-free survival (PFS) rate were 66 and 56 %, respectively. Findings on post-treatment positron emission tomography-computed tomography (PET-CT) were significantly associated with OS (34 % for patients with abnormal uptake vs. 75 % for those without, P = 0.014), and were also associated with PFS (36 vs. 83 %, respectively, P < 0.001). Nine patients with a single site of abnormal uptake on PET-CT underwent radiotherapy and 5 of them subsequently relapsed. An initial bulky mass does not indicate a poor prognosis of DLBCL. However, the post-treatment PET-CT findings may have predictive value in DLBCL patients with a bulky mass.