Cancer in Organ Recipients With Metastatic Spread to Transplant Organs: A Systematic Review

PURPOSE: Metastatic spread of cancer to transplanted organs is rare, with no prior systematic review. As both the number of transplant recipients and their long term survival increase, such cases may become more common. This systematic review seeks to synthesize all existing case studies describing metastases in transplanted organs. METHODS: A systematic search of EMBASE and PUBMED was conducted following PRISMA guidelines (PROSPERO: CRD420251119412). Eligible studies described cancer originating from the graft recipient metastasizing to a transplant organ. Studies were summarized across six key domains: patient characteristics, primary tumor types, transplant history, imaging, metastatic cancer treatment, and complications and mortality. RESULTS: Of the 643 studies identified and screened, 12 met the inclusion criteria. The mean patient age was 58 years (±11 years). Affected organs included the liver (n = 7), kidney (n = 4), and lung (n = 1). The most common primary cancer was colorectal cancer. Immunosuppression regimens most often included tacrolimus or cyclosporine. Most studies used CT (n = 6) as the imaging modality to detect metastases. Due to the high prevalence of colorectal cancers, the most common therapy administered was chemotherapy consisting of 5-fluorouracil, oxaliplatin, and folinic acid. Three studies reported complications and seven reported patients passing away. CONCLUSION: Metastatic spread to transplanted organs is extremely rare and/or under-reported. Further research may help reveal more about the process of metastatic spread, guide screening, and standardize reporting.