Wilms tumor: Preoperative risk factors identified for intraoperative tumor spill

Purpose: We identified preoperative parameters associated with increased risk of intraoperative Wilms tumor spill. Materials and Methods: We retrospectively reviewed an institutional database of patients diagnosed with Wilms tumor between 2000 and 2008. Inclusion criteria consisted of available abdominal computerized tomogram and pathological stage I to IV disease. Patient characteristics and neoadjuvant chemotherapy use were noted. After blinding, a radiologist reviewed preoperative computerized tomogram parameters, calculating tumor volume and assigning a preoperative radiological stage. Results: Of 67 patients diagnosed with Wilms tumor 41 (22 males, 19 females) met inclusion criteria, while 26 had incomplete imaging for analysis. Comparison of patients with and without intraoperative tumor spill demonstrated no significant differences in age (3.8 vs 3.6 years), sex (3 males and 3 females vs 19 males and 16 females), body weight or tumor capsule thickness. Preoperative radiological staging was unable to predict pathological stage I to III disease. Six intraoperative tumor spills (15%) were identified (left in 4, right in 2), of which 3 were stage III disease and 3 stage IV. Without neoadjuvant chemotherapy, patients with tumors greater than 1,000 cc had an increased risk of spill (2 of 2 [100%] vs 4 of 33 [12%], p = 0.03). Of 9 patients with stage IV disease 0% (0 of 4) receiving neoadjuvant chemotherapy experienced tumor spill, while lack of neoadjuvant chemotherapy was associated with a 60% (3 of 5 patients, 1 male and 2 females) risk of stage IV spill (p = 0.17). Conclusions: The sole significant tumor spill risk factor identifiable preoperatively was tumor volume greater than 1,000 cc. However, spill occurred at volumes less than 400 cc. Although not statistically significant, neoadjuvant chemotherapy for stage IV disease trended toward diminishing spill risk. Patients with Wilms tumors greater than 1,000 cc may benefit from neoadjuvant chemotherapy with less tumor spill, while stage IV tumors warrant further study in this regard.