Partial hepatectomy in metastatic Wilms' tumor

The role of liver resection in metastatic nephroblastoma: a systematic review and Meta-regression analysis

BACKGROUND

The impact of hepatic resection for liver metastases (LM) on the survival of pediatric patients with Wilms' tumor (WT) is unclear. So far, there is a lack of studies investigating the best suited treatment for patients with WTLM, and the role of liver resection has rarely been investigated. Thus, the development of evidence-based guidelines concerning indications of liver resection for WTLM remains difficult.

AIM

To investigate the role of surgery in the therapy of WTLM. All available data on liver resections and subgroup outcomes of patients with WTLM are analyzed. Main research question is whether liver resection improves survival rates of patients with WTLM compared to non-surgical treatment.

METHODS

A systematic literature search of MEDLINE, Web of Science, and Central provided the basis for this PRISMA-compliant systematic review. For the main analysis (I), all studies reporting on surgical treatment of pediatric WTLM were included. To provide a representative overview of the general outcome of WTLM patients, in analysis II all studies with cohorts of at least five WTLM patients, regardless of the kind of treatment, were reviewed and analyzed. A Multiple meta-regression model was applied to investigate the impact liver resection on overall survival.

RESULTS

14 studies with reports of liver resection for WTLM were found (Analysis I). They included a total of 212 patients with WTLM, of which 93 underwent a liver resection. Most studies had a high risk of bias, and the quality was heterogenous. For the analysis II, eight studies with subgroups of at least five WTLM patients were found. The weighted mean overall survival (OS) of WTLM patients across the studies was 55% (SD 29). A higher rate of liver resection was a significant predictor of better OS in a multiple meta-regression model with 4 covariates (I2 29.43, coefficient 0.819, p = 0.038).

CONCLUSIONS

This is the first systematic review on WTLM. Given a lack of suited studies that specifically investigated WTLM, ecological bias was high in our analyses. Generating evidence is complicated in rare pediatric conditions and this study must be viewed in this context. Meta-regression analyses suggest that liver resection may improve survival of patients with WTLM compared to non-surgical treatment. Especially patients with persisting disease after neoadjuvant chemotherapy but also patients with metachronous LM seem to benefit from resection. Complete resection of LM is vital to achieve higher OS. Studies that prospectively investigate the impact of surgery on survival compared to non-surgical treatment for WTLM are highly needed to further close the current evidence gap.

STUDY REGISTRATION

PROSPERO 2021 CRD42021249763  https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=249763 .

Proposal for a Clinical Classification of Liver Metastases

The lack of a worldwide-accepted classification of liver metastases makes it difficult to compare data on natural history and results from different treatments. The increasing interest in aggressive multimodal therapies for hepatic metastases prompted us to review the chief prognostic factors and the main published classifications in order to propose a new clinical classification, whose principal application concerns metastases from colorectal adenocarcinomas. Following the general rules of the TNM classification, liver metastases are classified by expressing with letters and numbers the parameters selected for their prognostic importance, clinical applicability and objectivity. H (hepatic) is the letter that indicates the liver is the site of metastasis. Synchronous metastases are indicated by H, metachronous by rH (r = recurrent). The extent of liver involvement is defined: H1, liver involvement less than 25%; H2, from 25 to 50%; H3, more than 50%. Site of metastases is defined by s (single), m (multiple to one surgical lobe), b (to both lobes), i (infiltration of important structures). The alteration of liver functions is indicated by F. The presence of cirrhosis is noted by C.

Response rates in relapsed Wilms' tumor. A need for new effective agents

Three hundred eighty-one children with Wilms' tumor were treated in the United Kingdom Children's Cancer Study Group WT1 Study (1982 to 1986). Seventy-one patients had relapses during or after treatment with surgery and chemotherapy, and radiation therapy, depending on stage and histologic characteristics. Forty-nine patients were evaluable for disease response to second-line chemotherapy alone. Evaluation of response to chemotherapy was impossible in the remaining patients because either surgery or radiation therapy was used at the time of relapse. With second-line combination chemotherapy (which included ifosfamide, etoposide/VM26, cisplatin/carboplatin, bleomycin, melphalan, and Thiotepa [Lederle Laboratories, Pearl River, NY]), there were five complete responses and 12 partial responses. In patients with favorable histologic findings, six of nine with Stage I, five of ten with Stage II, none of 11 with Stage III, three of 16 with Stage IV, and one of five with Stage V disease survived. Two survivors were treated with chemotherapy alone; the others received combined treatment with chemotherapy, radiation therapy, and/or surgery. For those with unfavorable histologic findings of any stage, only two of 20 survived. The authors conclude that, even for patients with localized disease with favorable histologic findings, the "salvage" rate is little more than 50%, and for all other stages and histologic findings the likelihood of cure after relapse is remote. There is clearly a need for additional effective chemotherapeutic agents for these patients.

How curable is relapsed Wilms' tumour? The United Kingdom Children's Cancer Study Group

Three hundred and eighty one children with Wilms' tumour were treated on the United Kingdom Children's Cancer Study Group WT1 Study (1980/6). Seventy one patients relapsed during or after treatment, which included surgery and chemotherapy, with irradiation depending on stage and histology. Despite treatment with various combinations of chemotherapy, surgery, and radiotherapy there were only 17 survivors. For unfavourable histology, any stage, only two of 20 survive. We conclude that, after relapse, even for patients who have had localised disease and favourable histology, the 'salvage' rate is little more than 50% and for all others the likelihood of cure is very small. Three of 41 children who relapsed less than 12 months from diagnosis survive, compared with 14 of 30 who relapsed later. It is essential that even with this 'good prognosis' tumour initial treatment is optimal and given by centres experienced in management of children's cancer. Furthermore, there is a clear need for additional effective chemotherapeutic agents for relapsed patients.

Survival after liver resection for secondary tumors

The results achieved by liver resection for metastatic cancer in more than 400 patients have been studied in a collected review. Certain conclusions seem justified: The liver is no longer the surgeon's "no-man's-land," and local excision of metastatic tumor can achieve clinical cure in some patients. The risk-benefit ratio for hepatic resection for secondaries seems to be shifting in favor of benefit for selected patients with primary colorectal tumors. At present liver resection for tumors metastatic from pancreas, breast, lung, stomach, kidney, reproductive organs, and skin (melanoma) cannot be recommended. Liver resection may play an important part in the multi-modal therapy of children with extensive malignant disease.

Major hepatic resections in children

Twenty-three major hepatic resections in children are presented. An unusually low number of associated injuries is noted in the trauma group. There was one operative death and complications were limited to five patients. Biliary decompression was not employed. Complications did not include respiratory, renal, or hepatic failure. Gastrointestinal bleeding was not seen. Although debridement seems adequate for subsegmental injuries, anatomic lobectomy must be considered for more severe injuries involving multiple segments of a single lobe.