Impact of neoadjuvant chemotherapy on thrombus viability in patients with Wilms tumour and caval extension: systematic review with meta-analysis

Abstract

Background Inferior vena cava (IVC) tumour thrombus in children with Wilms tumour is typically managed with neoadjuvant chemotherapy with the intention of achieving thrombus regression in order to minimize the risks associated with complex vascular surgery. Methods A systematic review of Medline and Embase databases was undertaken to identify all eligible studies with reference to thrombus viability in Wilms tumour index cases with caval/cardiac extension. A meta-analysis of proportions was utilized for pooled thrombus viability data across studies. Logistic regression was used to analyse the relationship between thrombus viability and duration of chemotherapy. Results Thirty-five eligible observational studies and case reports met inclusion criteria describing a total of 236 patients with thrombus viability data. The pooled proportion of patients with viable tumour thrombus after neoadjuvant chemotherapy was 0.53 (0.43–0.63). Logistic regression analysis of 54 patients receiving either a standard (4–6 weeks) or extended (more than 6 weeks) course of neoadjuvant chemotherapy resulted in an odds ratio of 3.14 (95 per cent c.i. 0.97 to 10.16), P = 0.056, with extended course therapy trending towards viable tumour thrombus. Conclusion Preoperative chemotherapy is successful in achieving non-viability of caval and cardiac thrombi in around 50 per cent of children, without added benefit from extended cycles of neoadjuvant chemotherapy. Risks versus benefits of extirpative vascular surgery must be considered, therefore, for these high-risk patients.

Management of Pediatric Tumors With Vascular Extension

“…Some authors advise radiotherapy to treat the thrombus instead of surgical resection ( 5 ), but we think that depending on the presence or absence of viable cells within the thrombus, radiotherapy may be avoided if complete surgical resection is achieved.…”

“…Contralateral renal vein ligation is justified and safe due to the development of collaterals venous of the azygo's system while the tumor grows, which is responsible to keep adequate venous return to the contralateral kidney or adrenal ( 2 , 4 , 5 ). For this reason, there is no need for IVC prosthesis replacement.…”

“…In cases of WT, despite the differences on the initial approach between the cooperative groups Societé Internationale d'Oncologie Pediatrique (SIOP) in Europe and Children's Oncology Group (COG) in North America, both agree with the use of preoperative chemotherapy in cases with vascular extension, in an attempt to reduce the level of the extension, minimizing the surgical risks and the need for cardiac bypass (CBP) (5)(6)(7)(8)(9). The number of preoperative chemotherapy cycles depends on the tumor histology and its thrombus response.…”

Outcomes of incomplete thrombectomy in Wilms tumour with intravascular extension: A commentary

“…There were no recorded fatalities claimed from major haemorrhage in IMPORT. 1,8,15 This communication serves to reiterate and highlight the key debate with regards to outcome metrics specific to incomplete thrombectomy, in addition to effects of radiotherapy on the viability of thrombi, which has not previously been adequately addressed in the contemporary literature. It is crucial that we as surgeons and cancer care providers evaluate risks and benefits to patients and families when considering aggressive oncological surgery.…”

“…A recent meta-analysis exploring inferior vena cava (IVC) thrombus viability following chemotherapy in Wilms tumour (WT) found thrombus non-viability in some 50% of index cases. 1 The inherent risks of IVC thrombectomy should therefore be weighed against the potential outcomes of incomplete resection.…”