Cancer Risk in Solid Organ Transplant Recipients With a Pretransplant Cancer History

IMPORTANCE Cancer survivors are at elevated risk of developing subsequent cancers. Solid organ transplant (SOT) recipients also have elevated cancer risk, but the pattern of subsequent cancer risk among SOT recipients with a pretransplant cancer has not been studied. OBJECTIVE To assess the association of pretransplant cancers with posttransplant cancer risk among SOT recipients. DESIGN, SETTING, AND PARTICIPANTS This cohort study used linked data from the US Scientific Registry of Transplant Recipients and 34 population-based cancer registries, comprising 92% of the US SOT recipient population from 1995 to 2019. Data were analyzed from March to September 2025. EXPOSURE Pretransplant cancer diagnosis. MAIN OUTCOME AND MEASURES Incidence rate ratios (IRRs) were used to compare risk of posttransplant cancer among SOT recipients with vs without pretransplant cancer, adjusted for attained age, sex, and transplanted organ, for 581 combinations of pretransplant and posttransplant cancer types. IRRs were compared with standardized incidence ratios (SIRs), which assess subsequent cancer risk among cancer survivors in the general population, using US cancer registry data. RESULTS A total of 520 424 SOT recipients were evaluated in the analysis; the median (IQR) age at transplant was 52 (41-59) years. Seven types of pretransplant cancer were significantly associated with a risk of the same type of cancer after transplant (Bonferroni-corrected P value <8.6 × 10⁻⁵): breast (IRR, 3.71, 95% CI, 3.04-4.48), melanoma of the skin (IRR, 10.4; 95% CI, 7.43-14.1), lung (IRR, 3.65; 95% CI, 2.67-4.86), kidney (IRR, 2.34; 95% CI, 1.94-2.79), urinary bladder (IRR, 3.72; 95% CI, 2.44-5.39), liver (IRR, 1.73; 95% CI, 1.39-2.14), and colorectum (IRR, 2.38; 95% CI, 1.61-3.37). Other significant associations included liver followed by lung cancer (IRR, 1.63; 95% CI, 1.48-1.80) or by prostate cancer (IRR, 1.71; 95% CI, 1.53-1.92), urinary bladder followed by lung cancer (IRR, 2.55; 95% CI, 1.93-3.29), kidney followed by thyroid cancer (IRR, 2.87; 95% CI, 1.87-4.17), and intrahepatic bile duct followed by pancreatic cancer (IRR, 8.56; 95% CI, 3.66-16.7). These IRRs were lower than the corresponding SIRs for cancer survivors in the general population for 3 combinations of pretransplant and posttransplant cancer types (liver-liver, kidney-kidney, and lung-lung). CONCLUSIONS AND RELEVANCE This cohort study found that SOT recipients with pretransplant cancer had an elevated risk of posttransplant cancer, particularly of the same cancer type. These patterns likely reflect shared genetic or environmental risk factors. Among SOT recipients who had kidney, liver, or lung cancer before transplant, posttransplant cancer of the same organ may be associated with the underlying end-stage organ disease. Targeted cancer prevention and screening could benefit SOT recipients who have survived a cancer diagnosis before a transplant.