Value of PET Restaging After Chemotherapy for Non-Hodgkins Lymphoma: Implications for Consolidation Radiotherapy

Abstract

Purpose/Objective: Patients receiving chemotherapy for Non-Hodgkins Lymphoma (NHL) frequently are restaged afterwards for response using positron emission tomography (PET) scanning. This study investigates the role of subsequent consolidation radiation therapy (RT) based on PET response to chemotherapy.Materials/Methods: The IRB-approved database of the Lymphoma Clinic at the Winship Cancer Institute of Emory University was retrospectively queried for patients (pts) who underwent PET scans after treatment of NHL consisting only of chemotherapy between 1995 and 2004. Seventy-seven pts were identified. To determine if benefit was attained by the use of consolidation RT, these pts were subsequently followed for a median of 8.4 months (range 3.5 - 61.8 months) to determine overall survival and local control.Results: Median age of pts was 53 years (range 18–82 years). A multivariate analysis was performed to analyze factors influencing recurrent disease; age, indolent vs. aggressive histology, and time from chemotherapy to PET did not. PET positive scans (RR= 30.5, 95%CI=5.9, 156.4), stage I/II presentation (RR= 0.23, 95%CI=0.05, 0.97), and lack of RT (RR=5.25, 95%CI=1.26, 21.79) all predicted increased likelihood of recurrence. Patients who had persistently + PET scans after chemotherapy had a significantly higher risk of subsequent relapse than those whose PET scans cleared (58.1% vs 15.2%; p<0.0001), although not everyone with positive scans recurred. Patients with + PET scans receiving consolidation RT were not protected from relapse when compared to PET + patients not receiving consolidation RT (63.2% relapse with RT, 50% relapse without RT; p = 0.71). In fact, over half of the relapses in patients receiving RT for persistently + PET scans were in-field. For patients who had - PET scans after chemotherapy, consolidation RT contributed to numerically fewer relapses (6.2% vs 20%; p = 0.39). Survival was not significantly different between PET + and PET - cohorts, related to adequate salvage techniques available and relatively short follow-up.Conclusions: While RT may control relapse in PET - patients, NHL patients who remain PET + after chemotherapy are not well managed by RT alone. Purpose/Objective: Patients receiving chemotherapy for Non-Hodgkins Lymphoma (NHL) frequently are restaged afterwards for response using positron emission tomography (PET) scanning. This study investigates the role of subsequent consolidation radiation therapy (RT) based on PET response to chemotherapy. Materials/Methods: The IRB-approved database of the Lymphoma Clinic at the Winship Cancer Institute of Emory University was retrospectively queried for patients (pts) who underwent PET scans after treatment of NHL consisting only of chemotherapy between 1995 and 2004. Seventy-seven pts were identified. To determine if benefit was attained by the use of consolidation RT, these pts were subsequently followed for a median of 8.4 months (range 3.5 - 61.8 months) to determine overall survival and local control. Results: Median age of pts was 53 years (range 18–82 years). A multivariate analysis was performed to analyze factors influencing recurrent disease; age, indolent vs. aggressive histology, and time from chemotherapy to PET did not. PET positive scans (RR= 30.5, 95%CI=5.9, 156.4), stage I/II presentation (RR= 0.23, 95%CI=0.05, 0.97), and lack of RT (RR=5.25, 95%CI=1.26, 21.79) all predicted increased likelihood of recurrence. Patients who had persistently + PET scans after chemotherapy had a significantly higher risk of subsequent relapse than those whose PET scans cleared (58.1% vs 15.2%; p<0.0001), although not everyone with positive scans recurred. Patients with + PET scans receiving consolidation RT were not protected from relapse when compared to PET + patients not receiving consolidation RT (63.2% relapse with RT, 50% relapse without RT; p = 0.71). In fact, over half of the relapses in patients receiving RT for persistently + PET scans were in-field. For patients who had - PET scans after chemotherapy, consolidation RT contributed to numerically fewer relapses (6.2% vs 20%; p = 0.39). Survival was not significantly different between PET + and PET - cohorts, related to adequate salvage techniques available and relatively short follow-up. Conclusions: While RT may control relapse in PET - patients, NHL patients who remain PET + after chemotherapy are not well managed by RT alone.