SUO 2016: Management of Residual Retroperitoneal Masses after Chemotherapy for Advanced Seminoma

San Antonio, Texas USA (UroToday.com) The management of advanced testicular seminoma is significantly different from that of non-seminoma germ cell tumors (NSGCT). Seminoma is exquisitely sensitive to both chemotherapy and radiation therapy both showing ≥ 85% complete response following therapy. The management of post-chemotherapy residual masses in pure seminoma can be quite challenging since there is a paucity of consensus in the management of this patients especially for those with masses > 3 cm.

In the session, Dr. Andrew J. Stephenson from the Cleveland Clinic Foundation, presents the management of post-chemotherapy residual masses in patients with pure seminoma. The use of post-chemotherapy retroperitoneal lymph-node dissection (PC-RPLND) for the management advanced seminoma is low with a rate of 5-10% in pure seminoma series and represents < 10% of all PC-RPLND’s performed. In comparison to NSGCT, the yield of viable tumor after a PC-RPLND in pure seminoma is < 15% and is associated with great morbidity due to the desmoplastic reaction seen following chemotherapy. In addition, regression of residual mass is common with > 80% showing some evidence of regression and 50-60% showing complete resolution at a median follow-up of 12-18 months.

There two treatment paradigms in the management of residual masses > 3 cm in size, immediate resection vs. observation with delayed surgical resection or salvage chemotherapy for progressive disease.. Study from Rice and colleagues (J Urol 2014) looked the survival outcomes of patients managed with PC-RPLND vs. salvage chemotherapy in patients with residual pure seminoma who failed initial observation. The study showed a significant improved survival for patients undergoing PC-RPLND (75%) vs those receiving salvage chemotherapy (25%).

Patient selection is imperative given the associated morbidity with both PC-RPLND and salvage chemotherapy. Patients presenting with masses < 3 cm in size should be observed as the risk of harboring viable cancer ranges from 0-4%. In masses > 3cm FDG-PET CT scan has been introduced as a screening tool to aid in patient selection. The SEMPET trial, was a prospective multi-institutional evaluation FDG-PET for residual masses > 1 cm, which showed a specificity of 100% and with positive predictive value of 100% and negative predictive value of 96%. A retrospective validation of the SEMPET trial was performed at the University of Indiana (Lewis et al, J Clin Onc 2006) showing that no patients with PET negative scan relapsed, but showed a 33% false positive rate in all patients, increasing to 66% in patients with < 3 cm masses.

In summary, the therapeutic evidence of PC-RPLND in advanced seminoma is less certain compared to NSGCT mainly to the increase morbidity associated with the procedure. Residual masses < 3 cm should be observed as the risk for occult viable tumor is low. Patients with masses > 3 cm should be further evaluated with FDG PET scan, as patients with negative PET scan are very unlikely to recur and should be observed. For patient with PET positive scans the available options are immediate PC-RPLND vs. observation with delayed resection/salvage chemotherapy. There is paucity if data to guide “best practice”, but immediate PC-RPLND has been associated with improve survival relative to deferred surgery/chemotherapy in retrospective trials.

Presented By: Andrew J. Stephenson, MD, Cleveland Clinic Foundation

Written By: Andres F. Correa, MD, Society of Urologic Oncology Fellow, Fox Chase Cancer Center

17th Annual Meeting of the Society of Urologic Oncology - November 30 -December 2, 2016 – San Antonio, Texas USA

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