Solid organ transplantation in patients with preexisting malignancies in remission: a propensity score matched cohort study

Background — Solid organ transplant recipients (SOTR) with pretransplant malignancies (PTM) have worse overall survival (OS) compared to recipients without history of malignancy. However, it is unknown whether the increased risk of mortality is due to recurrent cancer-related deaths.

Methods — All SOTR in Ontario between 1991 and 2010 were identified and matched 1:2 to recipients without PTM using a propensity score. OS was compared using the Kaplan-Meier estimator and Cox proportional hazard models. For cancer-specific mortality and cancer recurrence, cause-specific hazard models were used and the cumulative incidence was plotted.

Results — Recipients with PTM had a worse OS compared to recipients without PTM (median OS: 10.3 versus 13.4 years). Recipients with PTM were not only at increased risk of cancer-specific mortality (CSHR:1.85 [95% CI: 1.20, 2.86]) but also at increased risk of noncancer death (CSHR:1.29 [95% CI: 1.08, 1.54]). Compared to recipients without PTM, recipients with high-risk PTM had higher all-cause mortality (HR:1.81 [95% CI: 1.47, 2.23]). Recipients with low-risk PTM were not at increased risk (HR:1.06 [95% CI: 0.86, 1.31]).

Conclusion — Recipients with PTM are at increased risk of all-cause mortality compared to recipients without PTM. This increased risk was noted for both cancer-specific and noncancer mortality. However, only those with high-risk PTM had worse outcomes.