Transplant Oncology: An Emerging Discipline of Cancer Treatment

Abstract

Transplant oncology is an emerging concept of cancer treatment with a promising prospective outcome. The applications of oncology, transplant medicine, and surgery are the core of transplant oncology to improve patients' survival and quality of life. The main concept of transplant oncology is to radically cure cancer by removing the diseased organ and replacing it with a healthy one, aiming to improve the survival outcomes and quality of life of cancer patients. Subsequently, it seeks to expand the treatment options and research for hepatobiliary malignancies, which have seen significantly improved survival outcomes after the implementation of liver transplantation (LT). In the case of colorectal cancer (CRC) in the transplant setting, where the liver is the most common site of metastasis of patients who are considered to have unresectable disease, initial studies have shown improved survival for LT treatment compared to palliative therapy interventions. The indications of LT for hepatobiliary malignancies have been slowly expanded over the years beyond Milan criteria in a stepwise manner. However, the outcome improvements and overall patient survival are limited to the specifics of the setting and systematic intervention options. This review aims to illustrate the representative concepts and history of transplant oncology as an emerging discipline for the management of hepatobiliary malignancies, in addition to other emerging concepts, such as the uses of immunotherapy in a peri-transplant setting as well as the use of circulating tumor DNA (ctDNA) for surveillance post-transplantation.

Keywords: cholangiocarcinoma; circulating tumor DNA; colorectal cancers; hepatocellular carcinoma; immunotherapy; liver metastases; liver transplantation; neuroendocrine tumor; transplant oncology.

Figure 1

Historical stairway demonstrating progression and expansion of Milan criteria for LT in patients with HCC. AFP: alpha fetoprotein, OS: overall survival, RFS: recurrence-free survival, TTV: total tumor volume.

Figure 2

Summary for current prospective trials on LT for colorectal liver metastases. CRLM: colorectal liver metastases, LT: liver transplant, TACE: transarterial chemoembolization, SIRT: selective internal radiation therapy, CT: chemotherapy, LDLT: liver donor liver transplantation, RPVL: right portal vein ligation, LR: liver resection; RCT: randomized controlled trial, HAI: hepatic artery infusion, LDLT: living donor liver transplantation, RAPID: resection and partial liver segment 2–3 transplantation with delayed total hepatectomy, PD: progressive disease, PR: partial response, SD: stable disease, CEA: carcinoembryonic antigen.