Kidney transplant recipients in Thailand face sharply elevated cancer risk, study finds

Kidney transplant recipients at a major Thai hospital developed de novo malignancies at a rate several times higher than the general population, according to a retrospective cohort study published in BMC Nephrology. Among 292 adults who received their first kidney transplant at Siriraj Hospital, Mahidol University, between January 2014 and December 2018, 20 patients, or 6.8 percent, were diagnosed with a new cancer during follow-up.

The study analyzed adult patients with a median age at transplantation of 44.0 years and a median follow-up of 8.7 years. Patients with a history of prior organ transplantation or pre-existing malignancy before their kidney transplant were excluded, so the findings reflect cancers that arose anew after transplantation. The median time from transplant to a cancer diagnosis was 4.0 years.

For all malignancies combined, the standardized incidence ratio was 3.71, with a 95 percent confidence interval of 2.27 to 5.73, indicating a substantially elevated overall burden of cancer in this group.

The most common malignancy was urothelial cancer, which accounted for 5 of the 20 cases, or 25 percent of all malignancies, and was particularly prevalent among female patients. Its standardized incidence ratio was strikingly high at 53.11, with a 95 percent confidence interval of 17.25 to 123.95. Post-transplant lymphoproliferative disorder was the second most frequent diagnosis, occurring in 3 cases, or 15 percent, with a standardized incidence ratio of 16.60 and a confidence interval of 3.42 to 48.51.

Renal cell carcinoma, breast cancer, and prostate cancer each accounted for 2 cases, or 10 percent of the total. The standardized incidence ratios for renal cell carcinoma, at 34.75, and prostate cancer, at 14.20, were both significantly elevated. The remaining malignancies appeared as single cases each, or 5 percent apiece: lung cancer, cutaneous squamous cell carcinoma, liposarcoma, cholangiocarcinoma, nasopharyngeal cancer, and chronic myeloid leukemia.

Despite the elevated incidence, the search for predictors of malignancy within the cohort came up empty. No clinical factor was significantly associated with post-transplant malignancy on univariate analysis, a limitation that underscores how difficult it remains to identify, in advance, which individual recipients will develop cancer.

The consequences of a malignancy diagnosis were substantial. Patient survival was significantly worse among recipients who developed malignancy: five-year survival was 85.0 percent in that group compared with 93.0 percent among recipients who remained cancer-free, a difference the researchers reported as statistically significant with a log-rank P value of 0.023.

Graft outcomes, however, followed a different pattern. Death-censored graft survival did not differ between the two groups, with a P value of 0.831, meaning that the presence of cancer was associated with higher mortality but not with loss of the transplanted kidney itself. Five of the 20 patients with malignancy, or 25.0 percent, died during the study period; four of those deaths were attributed to cancer and one to infection.

The authors conclude that kidney transplant recipients carry a significantly elevated risk of de novo malignancies, with urothelial cancer standing out as the most common type in this Thai cohort. Because malignancy was associated with reduced patient survival but not with death-censored graft survival, the findings point to cancer as a serious threat to long-term survival in this population.

The study’s authors emphasize that the results highlight the importance of vigilant cancer screening and continuous monitoring in kidney transplant recipients to enable early detection and effective management. As a single-center retrospective study of 292 patients, the analysis captures the experience of one Thai transplant program over a defined five-year transplant window, and the absence of significant risk factors on univariate analysis means the findings describe the cohort’s overall burden rather than a tool for predicting individual risk.

Subject of Research: Incidence, risk factors, and outcomes of de novo malignancy in Thai kidney transplant recipients

Article Title: Post-transplant malignancy in Thai kidney recipients: a single-center cohort study on incidence, risk factors, and outcomes

Article References: Ruchikajorndech, G., Suesatsakul, K., Larpparisuth, N., Skulratanasak, P., & Vongwiwatana, A. (2026). Post-transplant malignancy in Thai kidney recipients: a single-center cohort study on incidence, risk factors, and outcomes. BMC Nephrology. https://doi.org/10.1186/s12882-026-05455-2

Image Credits: AI Generated

DOI: 10.1186/s12882-026-05455-2

Keywords: kidney transplantation, de novo malignancy, urothelial cancer, post-transplant lymphoproliferative disorder, standardized incidence ratio, patient survival, graft survival, mTOR inhibitors, Siriraj Hospital, BMC Nephrology, cancer screening, immunosuppression