High incidence of false-positive PET scans in patients with aggressive non-Hodgkin's lymphoma treated with rituximab-containing regimens.
BACKGROUND
Positron emission tomography (PET) is a powerful predictor of relapse and survival in non-Hodgkin's lymphomas (NHLs) based on studies carried out in the prerituximab era. Little is known about the predictive power of PET in rituximab-treated patients.


METHODS
Patients with aggressive B-cell NHL with baseline and follow-up PET studies were included. Clinical characteristics, PET and computed tomography scans, biopsy results, and outcomes were reviewed. PET was defined as positive if higher than mediastinal or background activity was observed.


RESULTS
In all, 51 patients (diffuse large B cell-38; mantle cell lymphoma-13) treated with rituximab-containing regimens were included. For 13 of 40 patients (32.5%), mid-therapy PET studies were positive and 9 of 48 patients (18.7%) had positive posttherapy PET. The positive predictive value (PPV), negative predictive value (NPV), sensitivity (Se), and specificity (Sp) of the mid-therapy PET for predicting relapse were 33% [95% confidence interval (CI) 19% to 49%], 68% (95% CI 51% to 81%), 33% (95% CI 6% to 76%), and 68% (95% CI 49% to 82%), respectively. For posttherapy PET, the relapse PPV, NPV, Se and Sp were 19% (95% CI 9% to 33%), 81% (95% CI 67% to 91%), 13% (95% CI 0.6% to 53%), and 80%(95% CI 64% to 90%), respectively.


CONCLUSIONS
Compared with previous reports in prerituximab era, addition of rituximab resulted in reduced PPV and sensitivity of mid- and posttherapy PET in patients with aggressive B-cell NHL.
Division of Hematology and Oncology, The Sylvester Comprehensive Cancer Center, Miami, FL 33136, USA.
H S
HS
Han
M P
MP
Escalón
B
B
Hsiao
A
A
Serafini
I S
IS
Lossos
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D058846:Antibodies, Monoclonal, Murine-Derived; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage; D003520:Cyclophosphamide / Q000008:administration & dosage; D018572:Disease-Free Survival; D004317:Doxorubicin / Q000008:administration & dosage; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011241:Prednisone / Q000008:administration & dosage; D012008:Recurrence; D012189:Retrospective Studies; D000069283:Rituximab; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D014750:Vincristine / Q000008:administration & dosage; D055815:Young Adult
D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D019788:Fluorodeoxyglucose F18; D000069283:Rituximab; D014750:Vincristine; D004317:Doxorubicin; D003520:Cyclophosphamide; D011241:Prednisone