Liver Transplantation for Non-Resectable Liver Metastases from Colorectal Cancer: A Systematic Review and Meta-Analysis

Insights into the history and tendency of liver transplantation for liver cancer: a bibliometric-based visual analysis

Research on liver transplantation (LT) for liver cancer has gained increasing attention. This paper has comprehensively described the current status, hotspots and trends in this field. A total of 2991 relevant articles from 1 January 1963 to 28 February 2023 were obtained from the Web of Science Core Collection. VOSviewer and CiteSpace software were utilized as bibliometric tools to analyze and visualize knowledge mapping. Between 1963 and 2023, the number of papers in the area of LT for liver cancer increased continuously. A total of 70 countries/regions, 2303 institutions and 14 840 researchers have published research articles, with the United States and China being the two most productive countries. Our bibliometric-based visual analysis revealed the expansion of LT indications for liver cancer and the prevention/treatment of cancer recurrence as ongoing research hotspots over the past decades. Meanwhile, emerging studies also focus on downstaging/bridging treatments before LT and the long-term survival of LT recipient, in particular the precise application of immunosuppressants.

Liver transplantation for unresectable colorectal liver metastasis

PURPOSE OF REVIEW

To summarize the current state of liver transplantation (LT) for unresectable colorectal liver metastases (uCRLM), and to address future directions.

RECENT FINDINGS

The Norwegian secondary cancer (SECA) I and SECA II studies demonstrated that after LT the 5-year survival of a highly selected group of patients with uCRLM could be as high as 60% and 83%, respectively. After long-term follow-up, the 5- and 10-year survival was shown to be 43% and 26%, respectively. Furthermore, data has accumulated in other countries and a North American study reported a 1.5-year survival of 100%. In addition, steady growth has been demonstrated in the US, with 46 patients transplanted to date and 19 centers enrolling patients for this indication. Lastly, although recurrence is almost universal in patients with a high tumor burden, it has not been an accurate surrogate for survival, reflecting the relatively indolent nature of recurrence after LT.

SUMMARY

Growing evidence has shown that excellent survival and even cure can be achieved in highly selected patients with uCRLM, with survival rates far superior than in patients treated with chemotherapy. The next step is to create national registries to standardize selection criteria and establish the optimal approach and best practices for incorporating LT for uCRLM into the treatment armamentarium.

Updates and Expert Opinions on Liver Transplantation for Gastrointestinal Malignancies

Transplant oncology is a relatively new field in which transplantation is used to treat patients who would otherwise be unresectable. New anticancer treatment paradigms using tumor and transplant immunology and cancer immunogenomics are emerging. In turn, liver transplantation (LT) has become a potential therapy for certain patients with colorectal cancer (CRC) with liver metastasis, hepatocellular (HCC), cholangiocarcinoma (CCA), and metastatic neuroendocrine tumor (NET) of the liver. Although there are established criteria for LT in HCC, evidence regarding LT as a treatment modality for certain gastrointestinal malignancies is still debated. The aim of this review is to highlight updates in the role of LT for certain malignancies, including HCC, metastatic CRC, hilar CCA, and neuroendocrine tumor (NET), as well as contextualize LT use and discuss controversies in transplant oncology.

The evolution of the liver transplant candidate

The first successful human liver transplant (LT) was done over 60 years ago; since the early pioneering days, this procedure has become a routine treatment with excellent outcomes for the great majority of recipients. Over the last six decades, indications have evolved. Use of LT for hepatic malignancy is becoming less common as factors that define a successful outcome are being increasingly defined, and alternative therapeutic options become available. Both Hepatitis B and C virus associated liver disease are becoming less common indications as medical treatments become more effective in preventing end-stage disease. Currently, the most common indications are alcohol-related liver disease and metabolic associated liver disease. The developing (and controversial) indications include acute on chronic liver failure, alcoholic hepatitis and some rarer malignancies such as non-resectable colorectal cancer liver metastases, neuroendocrine tumours and cholangiocarcinoma. Candidates are becoming older and with greater comorbidities, A relative shortage of donor organs remains the greatest cause for reducing access to LT; therefore, various countries have developed transparent approaches to allocation of this life saving and life enhancing resource. Reliance on prognostic models has gone some way to improve transparency and increase equity of access but these approaches have their limitations.

Conversion Strategy in Left-Sided RAS/BRAF Wild-Type Metastatic Colorectal Cancer Patients with Unresectable Liver-Limited Disease: A Multicenter Cohort Study

Colorectal cancer (CRC) patients frequently develop liver metastases. Different treatment strategies are available according to the timing of appearance, the burden of metastatic disease, and the performance status of the patient. Systemic treatment (ST) represents the cornerstone of metastatic disease management. However, in select cases, combined ST and surgical resection can lead to remarkable survival outcomes. In the present multicentric cohort study, we explored the efficacy of a conversion strategy in a selected population of left-sided RAS/BRAF wild-type CRC patients with liver-limited metastatic disease. Methods: The primary endpoint was to compare survival outcomes of patients undergoing ST not leading to surgery, liver resection after conversion ST, and hepatic resection with perioperative ST. Furthermore, we explored survival outcomes depending on whether the case was discussed within a multidisciplinary team. Results: Between 2012 and 2020, data from 690 patients respecting the inclusion criteria were collected. Among these, 272 patients were deemed eligible for the analysis. The conversion rate was 24.1% of cases. Fifty-six (20.6%) patients undergoing surgical resection after induction treatment (i.e., ultimately resectable) had a significant survival advantage compared to those receiving systemic treatment not leading to surgery (176 pts, 64.7%) (5-year OS 60.8% and 11.7%, respectively, Log Rank test p < 0.001; HR = 0.273; 95% CI: 0.16−0.46; p < 0.001; 5-year PFS 22.2% and 6.3%, respectively, Log Rank test p < 0.001; HR = 0.447; 95% CI: 0.32−0.63; p < 0.001). There was no difference in survival between ultimately resectable patients and those who had liver resection with perioperative systemic treatment (potentially resectable—40 pts) (5-year OS 71.1%, Log Rank test p = 0.311. HR = 0.671; 95% CI: 0.31−1.46; p = 0.314; 5-year PFS 25.7%, Log Rank test p = 0.305. HR = 0.782; 95% CI: 0.49−1.25; p = 0.306). Conclusions: In our selected population of left-sided RAS/BRAF wild-type colorectal cancer patients with liver-limited disease, a conversion strategy was confirmed to provide a survival benefit. Patients not deemed surgical candidates at the time of diagnosis and patients judged resectable with perioperative systemic treatment have similar survival outcomes.

PET-Uptake in Liver Metastases as Method to Predict Tumor Biological Behavior in Patients Transplanted for Colorectal Liver Metastases Developing Lung Recurrence

The objective of the study was to determine the impact of PET uptake on liver metastases on overall survival (OS) after resection of pulmonary metastases in patients who had received liver transplantation (LT) due to unresectable colorectal liver-only metastases. Resection of pulmonary colorectal metastases is controversial. Some hospitals offer this treatment to selected patients, whereas other hospitals do not perform the procedure in colorectal cancer patients who develop pulmonary metastases. All patients included in the LT studies who developed pulmonary metastases as first site of relapse, and had resection of these as first treatment, were included in this report. Metabolic tumor volume (MTV) in liver was derived from the pre-transplant PET examinations. OS from time of resection was calculated by the Kaplan−Meier method. Patients with low MTV (<70 cm3) had significantly longer OS from time of resection of pulmonary metastases compared to patients with high MTV (>70 cm3). Patients with low MTV in the liver had 10-year OS from time of pulmonary resections of 86%. Liver MTV values from pre-transplant PET examinations may predict long OS in colorectal cancer patients with a resection of pulmonary metastases developing after LT. Thus, in selected colorectal cancer patients developing pulmonary metastases resection of these metastases should be the treatment of choice.