Utility of positron emission tomography scans in mantle cell lymphoma

Abstract

Positron emission tomography (PET) scans are widely used in patients with lymphoma but little is known about their utility in mantle cell lymphoma (MCL). MCL patients were included from two prospective trials and one observational study at our institution. A total of 276 PET scans were performed among 52 patients. After a median follow-up of 37.5 months, the 3-year event-free survival (EFS) and overall survival (OS) were 73% (95% confidence interval [CI]: 61-85%) and 92% (95% CI 85-100%), respectively. There were 34 pretreatment PET scans, 26 interim, 28 end-of-treatment, 162 surveillance, and 26 scans at relapse or beyond. Pretreatment PETs were positive in 94%. A negative interim or end-of-therapy PET scan was not significantly associated with better EFS or OS, but no deaths were observed in patients who had a negative interim or end-of-therapy PET. Surveillance PET scans had a high false positive rate (35%) and low positive predictive value (8%). PET scans contributed to an earlier diagnosis of relapse in only two out of the 18 patients (11%) who relapsed. PET scans did not meaningfully contribute to staging or surveillance of MCL patients in this study. There was a trend toward improved survival in patients who had a negative end-of-therapy PET scan.

18F-FDG PET for Measurement of Response and Prediction of Outcome to Relapsed or Refractory Mantle Cell Lymphoma Therapy with Bendamustine–Rituximab

“…Likewise, another retrospective study found 18 F-FDG PET useful to predict PFS at 1 y in patients with MCL receiving rituximab and cytarabine-or anthracycline-based therapies (18). A third retrospective review of 28 available end-of-treatment scans (all in patients receiving rituximab-containing treatment) did not observe a statistically significant association between CMR and 3-y survival; however, no deaths were reported among patients with negative end-of-treatment scans, making a trend for better OS but not 3-y event-free survival (25). Similarly, a retrospective analysis of posttreatment 18 F-FDG PET scans for patients with MCL initially treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone found no differences in OS or PFS at 3 y between patients with positive and negative scans (26).…”

Mantle cell lymphoma: evolving management strategies

“…MCL is a PET-positive tumor; however, PET scanning does not reliably detect bone marrow or bowel disease and therefore does not add to conventional staging. 71,72 In 3 large studies involving patients treated with different regimens, a positive PET scan did not predict for an inferior OS when used either as an interim assessment or at the end of therapy. 71,73,74 One of these studies did show a significant difference in PFS following a positive PET at the completion of therapy, 74 and 1 other smaller study found a positive post-therapy scan was more likely to predict for relapse.…”

“…71,72 In 3 large studies involving patients treated with different regimens, a positive PET scan did not predict for an inferior OS when used either as an interim assessment or at the end of therapy. 71,73,74 One of these studies did show a significant difference in PFS following a positive PET at the completion of therapy, 74 and 1 other smaller study found a positive post-therapy scan was more likely to predict for relapse. 72 When used for surveillance, a high false-positive rate (35%) has been reported, 71 and in 2 studies where surveillance was assessed, it was concluded that PET scanning did not meaningfully contribute.…”

“…71,73,74 One of these studies did show a significant difference in PFS following a positive PET at the completion of therapy, 74 and 1 other smaller study found a positive post-therapy scan was more likely to predict for relapse. 72 When used for surveillance, a high false-positive rate (35%) has been reported, 71 and in 2 studies where surveillance was assessed, it was concluded that PET scanning did not meaningfully contribute. 71,75 It is not clear what role PET scanning currently has in this disease, but it is clear that a change of therapy should not be made based on an interim assessment, and it has no role in surveillance.…”

“…72 When used for surveillance, a high false-positive rate (35%) has been reported, 71 and in 2 studies where surveillance was assessed, it was concluded that PET scanning did not meaningfully contribute. 71,75 It is not clear what role PET scanning currently has in this disease, but it is clear that a change of therapy should not be made based on an interim assessment, and it has no role in surveillance. The significance of a positive PET after therapy is sufficiently unclear, suggesting that response criteria based on PET scanning should be applied with great caution in this disease.…”