618P - Adult renal Ewing’s sarcoma/primitive neuroectodermal tumor: A 20-year retrospective review of molecular histopathological profiles, and clinical outcomes

Background

Renal Ewing’s sarcoma/primitive neuroectodermal tumor (ES/PNET) among adults is an extremely rare malignancy. Accurate diagnosis mandates detailed immunohistochemistry (IHC) and molecular characterization. There is limited data on the treatment of these patients. We present a clinicopathological and molecular profile of renal ES/PNET from a single South Indian tertiary referral center.

Methods

We conducted a retrospective study of adults with a histopathological diagnosis of renal ES/PNET treated at our center over the last 20 years. All patients had received a standard treatment protocol of VAC/IE. Principal outcomes were event-free survival (EFS), overall survival (OS) and adverse events during treatment.

Results

We included 25 patients with renal ES treated at our center from 2003-2023. 68% were male, with median age 29(18-53). 8(32%) had localised disease and 17(68%) had recurrent/metastatic disease; lung(36%) and bone(28%) were the common sites of metastases. Median tumour size was 13.5cm and renal vein/IVC thrombus was present in 11(55%) patients. IHC(done in 24 patients), showed CD99 +, NKX 2.2 + in 100% and FLI1 + in 93.7%. RT-PCR/FISH done in 15 patients revealed EWS-FLI1 translocations in 5 patients, 4 of which were Type 1. Nephrectomy was performed in 19 patients: 8 radical for non-metastatic and 11 palliative for metastatic disease. 16 received systemic therapy, the median number of cycles being 10(Range:2-16). 11 patients received concurrent radiation. Grade 3/4 anaemia, thrombocytopenia, neutropenia, and febrile neutropenia was seen in 1(6.6%),1(6.6%),8(50%) and 8(50%) patients respectively during VAC/IE. Only 50% of patients had long term follow up. Survival at 3 years is 64.3%(83% for localised disease, 57.3% for recurrent/metastatic).

Conclusions

This study represents a substantial cohort of adult patients with renal ES/PNET undergoing a unified treatment approach. Predominantly, tumors presented as extensive and locally aggressive with favourable survival for localised disease. While these observations offer valuable insights, the rarity of the disease underscores the need for larger, multicentric studies for more definitive conclusions.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.