H. M. Phelps1, G. D. Ayers2, J. M. Ndolo3, H. L. Dietrich4, K. D. Watson5, M. A. Hilmes3, H. N. Lovvorn6 1Vanderbilt University Medical Center,School Of Medicine,Nashville, TN, USA 2Vanderbilt University Medical Center,Division Of Cancer Biostatistics,Nashville, TN, USA 3Vanderbilt University Medical Center,Pediatric Radiology,Nashville, TN, USA 4Vanderbilt University Medical Center,School Of Nursing,Nashville, TN, USA 5Vanderbilt University Medical Center,Pediatric Hematology/Oncology,Nashville, TN, USA 6Vanderbilt University Medical Center,Pediatric Surgery,Nashville, TN, USA
Introduction: Embryonal tumors arise typically in infants and young children and are often massive at presentation. Treatment is multimodal, and while complete resection is a critical element, surgery can interrupt therapy. When appropriate, minimally invasive surgery (MIS) offers a potential means to minimize treatment delays. However, the use of MIS to resect embryonal tumors remains controversial regarding the oncologic integrity of this approach.
Methods: A retrospective review of embryonal tumors treated at a single institution over a 15-year period was conducted to: 1) assess candidacy of embryonal tumors for MIS, and 2) evaluate outcomes for patients undergoing MIS versus open resection. Query of the institution’s cancer registry identified pediatric patients treated for intracavitary embryonal tumors from 2002 to 2017. To assess amenability for MIS, tumor volume (TV) and image-defined risk factors (IDRF, neuroblastic tumors only) were measured radiographically at time of diagnosis and immediately before resection. Stage, Children’s Oncology Group risk stratification, procedure-related details, delay to next dose of chemotherapy, relapse-free survival (RFS), and overall survival (OS) were evaluated. Wilcoxon, Pearson chi-square, and log-rank tests were performed.
Results: A total of 201 patients were treated for neuroblastic tumors (NBL, n=101), Wilms tumor (WT, n=66), hepatoblastoma (n=23), rhabdomyosarcoma (RMS, n=10), and pancreatoblastoma (n=1). Among these patients, 175 tumors were resected either open (n=151, 86%) or by MIS (n=24, 14%; 20 NBL, 3 WT, 1 RMS). Of the 174 with complete data at time of analysis, the median TV at resection was 84.8 ml [IQR 20.4, 372.5]. For NBL cases, a significantly greater proportion of MIS resections (n=17, 94%) had no IDRF when compared to open resections (n=31, 48%; p<0.001). For the entire cohort, RFS at 5 years was 0.78 [CI 0.71–0.85] for open resection versus 0.90 [CI 0.78–1.00] for MIS (p=0.463). OS at 5 years was 0.87 [CI 0.81–0.93] for open resection versus 1.00 [CI 1.00–1.00] for MIS (p=0.294). The largest TV resected via MIS was 93.4 ml, so subgroup comparisons were adjusted for TV<100 ml. No significant difference in margin status between open resection (n=68) and MIS (n=23) was observed, and MIS was associated with significantly less blood loss, shorter hospital stays, shorter operating time, and quicker return to the next chemotherapy cycle (Table 1).
Conclusion: For appropriately selected patients, MIS resection of pediatric embryonal tumors, particularly NBL, maintains an acceptable oncologic integrity while minimizing treatment delays, but large tumor volume, vascular encasement, and small patient size limit its broader applicability.
