L. Kane1, H. Savas1, M. DeCamp1, A. Bharat1 1Feinberg School Of Medicine – Northwestern University,Chicago, IL, USA
Introduction:
Mediastinal lymphoma affects young individuals, typically in the second through fourth decades of life, and constitutes over 7% of all lymphomas. The primary treatment modality remains systemic chemotherapy with or without radiation. Response to therapy is determined using PET scan. Unfortunately, in over 25% of patients, PET remains positive and it is unclear whether persistent PET avidity in the mediastinum represents residual disease or inflammatory changes resulting from therapy. Percutaneous image guided biopsy has typically resulted in poor accuracy due to the heterogeneity of the residual mass as well as the difficult nature of needle access. We hypothesized that minimally invasive thoracoscopic techniques would enable better sampling of the PET avid mediastinal lesion, allowing accurate assessment of residual disease following first-line treatment of mediastinal lymphomas.
Methods:
This is a retrospective analysis of a prospectively maintained database. Between January 2009 and December 2015, all patients (n=77) who underwent initial surgical incisional biopsy for diagnosis were included. The surgical biopsies were performed using minimally invasive techniques (video-thoracoscopy or robotic surgery) and required the surgeon to keep performing the biopsy until frozen section was positive or at least until the mass on the ipsilateral hemi-mediastinum was resected. Statistical analysis was performed by a biostatistician using SPSS software.
Results:
Of the study cohort, 34 patients underwent surgical restaging for PET avid residual mass while 43 either had a complete response with no PET activity or were lost to follow up. The cohort of 34 patients included 76% Caucasians, 50% females, and had a median age of 28 years. The types of lymphoma were predominantly Hodgkins (32%) and Diffuse Large B cell Lymphoma (38%). In these 34 patients with residual PET activity, surgical biopsy revealed presence of lymphoma in 53% of patients. Patients detected to have persistent lymphoma revealed no significant difference in tumor volume reduction compared to those with no residual disease (51% versus 39%) and no significant difference in reduction in PET SUV (68% versus 60%). In all biopsies, significant adhesions between lung and mediastinum were noted, and the median length of the surgical procedure was 75 minutes. However, there were no surgical complications. The length of stay for all patients was less than 24 hours. All patients detected to have residual lymphoma underwent second-line therapy guided by the pathological analysis.
Conclusion:
While the current standard for patients with mediastinal lymphoma presenting with residual PET activity after completion of first line therapy is surveillance alone, our data suggests that a large number of these patients have residual lymphoma which can be safely diagnosed using minimally invasive surgery. Detection of residual lymphoma has significant implications in further treatment of these patients.