Solid organ transplant recipients (SOTR) with a pre-transplant malignancy (PTM) have been thought to be at high risk of cancer recurrence. However, recent population-based studies report cancer recurrence rates in SOTR similar to those of non-transplant patients. A systematic search was performed in MEDLINE, EMBASE, and Cochrane Library to identify studies reporting cancer recurrence in SOTR with PTM. Quality assessment was performed using a validated tool for assessing the quality of an observational study with no control group designed by the Institute of Health Economics. Overall and site-specific recurrence rates per person-year were pooled using generalized linear random/mixed-effects meta-analysis models and an exact likelihood approach based on a binomial and Poisson distribution. Meta-regressions, subgroup and sensitivity meta-analyses were used to explore sources of heterogeneity. Fifty-seven eligible studies were identified and 39 were included in the meta-analysis. The pooled recurrence rate was 1.6 (95% CI 1.0-2.6) per 100 person-year for all studies, and 1.1 (95% CI 0.5-2.7) when restricted to population-based studies. The recurrence rate was higher for kidney (2.4 per 100 person-year, 95% CI 1.0-5.6) compared with liver (1.0 per 100 person-year, 95% CI 0.4-2.6), and cardiothoracic recipients (1.3 per 100 person-year, 95% CI 0.6-2.7). Time from cancer diagnosis to transplantation (TCT) ≤ 5 years was associated with greater risk of cancer recurrence compared to TCT > 5 years (risk ratio: 2.80, 95% CI 1.12-7.01). In conclusion, the risk of cancer recurrence in recipients with PTM is considerably lower than historic reports used to establish recommendations for listing patients with PTM. Evidence to support minimum cancer remission times before transplantation is limited.
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