Pontrelli P, et al. - Researchers performed this multicentre, observational, perspective, case–control study to determine a soluble diagnostic marker for monitoring the development of post-transplant malignancies. This study included 47 patients with post-transplant solid neoplasia and 106 transplant recipients without a history of neoplasia as controls. Comparing patients with and without post-transplant malignancies, 535 differentially expressed genes were identified. A close association of the cancer pathway with gene expression data was noted, and interleukin-27 (IL-27), a cytokine regulating anti-tumour immunity, was identified as one of the most down-regulated genes in this pathway. The microarray data were corroborated using quantitative polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). With a specificity of 80% and a sensitivity of 81%, IL-27 plasma levels allowed differentiation of patients with post-transplant neoplasia. Using an independent set of patients from two different transplant centres, this finding was corroborated. Overall, IL-27 could have the potential as an immunological marker to offer timely detection of post-transplant neoplasia.