Reliability of Intraoperative Frozen Section and a Vascular Access Decision-Tree for Children and Adolescents Undergoing Surgery for Renal Masses Suspicious for Malignancy
Alonso Carrasco, Jr., MD, Brian T. Caldwell, MD, Nicholas G. Cost, MD.
Children's Hospital of Colorado, Denver, CO, USA.
BACKGROUND: Children and adolescents with renal malignancy often require multimodal therapy including surgery, radiation, and chemotherapy, depending on a combination of patient and tumor characteristics. Optimally, the surgical care could be consolidated such that all necessary interventions are performed in one setting. While the majority of these patients require placement of long-term vascular access (Mediport, Broviac, etc.) for adjuvant chemotherapy, certainly not all require vascular access (VA). Thus, placing VA in all patients represents unnecessary exposure to the risks (including pneumothorax or thrombosis) directly related to this procedure. Conversely, deferring the decision for VA placement until the final pathology/staging is available adds a potentially avoidable anesthetic exposure by returning to the operating room for VA placement. The study objective was to develop and test a decision-tree which takes into account factors available pre- and intra-operatively to direct the need for VA in patients with renal tumors.
METHODS: Utilizing factors (age, imaging, tumor characteristics, and frozen section) that are readily available at surgery, a decision-tree directing the need for VA placement was developed. The decision-tree was tested retrospectively by two independent reviewers on a historic patient cohort. The inter-rater reliability in using the decision-tree was assessed with Cohen’s kappa. Additionally, the ability of the decision-tree to appropriately select which patients would benefit from VA placement at the time of surgery was tested.
RESULTS: 126 patients with renal tumors suspicious for malignancy were identified between 2005 and 2015. Forty-two (33%) patients met study criteria with median age at diagnosis of 43mo (range 1.8-193mo). Final Pathology (FP) was: 32 (76.2%) Wilms Tumor, 3 (7.1%) Renal Cell Carcinoma, 2 (4.8%) Mesoblastic Nephroma, 1 (2.4%) of each: Renal Medullary Carcinoma, Cystic Nephroma, Angiomyolipoma, JGA Tumor, and Benign Pseudo-tumor. Frozen Section (FS) was performed in 28 patients, 25 (89%) correlated correctly with FP, kappa=0.818 (95%CI 0.636- 1.0, p<0.001).
Ultimately, 33 (78.6%) patients required VA placement based on FP and the clinical scenario. Using the decision-tree, VA placement was determined as needed in 30 (71.4%) and to be deferred in 12 (28.6%). Inter-rater reliability was high with a kappa=0.945 (95%CI 0.839-1.0, p<0.001). The ability of the decision-tree to correctly decide on VA placement was: Sensitivity=0.909 (95%CI 0.745-0.976), Specificity=1 (95%CI 0.629-1). There were no false positives, thus no patients would have required a second operation for removal of un-necessary VA. Conversely, there were 3 (7.1%) false negatives which would have required a second operative session for VA placement at a later date. Of these 3 patients where VA was potentially deferred un-necessarily by the decision-tree, only 2 (5%) would have required a second operation for VA placement based on contemporary treatment regimens.
CONCLUSION: These data support the use of intra-operative FS and a decision-tree to guide intra-operative decisions regarding the necessity of VA placement in a population of children and adolescents with suspected renal malignancy. Future work, including larger scale study of frozen section reliability in this population is required to further validate this decision tool.
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