Clinical utility of interim CT scans in patients receiving chemoimmuntherapy for first line treatment of follicular lymphoma

Interim imaging with computed tomography (iCT) to assess response is common during frontline chemoimmunotherapy for follicular lymphoma (FL), but there is little evidence of its utility. We retrospectively reviewed outcomes of iCT in 190 patients with biopsy-proven FL who received first-line chemoimmunotherapy from 2003-2018. Most iCTs showed partial response (PR, 83%), with a minority showing complete response (CR, 8%) or stable disease (5%). Seven patients (4%) had radiographic disease progression (PD) on iCT; on repeat biopsy, four had another malignancy identified and three had transformation to DLBCL. Only one had asymptomatic PD. The 3-year PFS of all patients was 74% (median follow up 75 months). Patients with PR on iCT had similar 3-year PFS and OS as those with CR. In conclusion, iCT has limited utility in identifying patients with asymptomatic early progression during first-line treatment. Patients with PD mid-treatment warrant biopsy to identify histologic transformation or other malignancies.