Abstract Body (Do not enter title and authors here):
Background

Colorectal cancer (CRC) risk is elevated in solid organ transplant recipients. However, data on CRC risk in heart transplant (HT) patients are limited. Also, screening recommendations for CRC in the HT population, especially patients under age 45, are lacking. Previous studies have been constrained by single-center designs, outdated cohorts, and lack of competing mortality analysis.

Objectives

We aimed to assess competing-risk incidence of post-HT CRC, with focus on the effect of age, to inform CRC screening recommendations.

Methods

We identified patients ≥18 years old at the time of HT in the TriNetX Research Network, which encompasses healthcare records from over 80 systems in the US, using CPT codes for HT (33945) and combined lung-HT (33935). CRC was identified from ICD-10 CM codes (C18, C19 & C20). Because mortality is significantly higher than CRC risk in this population, we used the Fine and Gray competing-risks framework to estimate CRC incidence for the entire cohort and subgroups of interest.

Results

We identified 4791 patients with HT or lung-HT between 1996 and 2024. After excluding 275 patients because of missing (N=266) or too short (N=9) follow-up, 4516 patients were included (Table 1). After a median follow up of 3.6 years (25^th – 75^th percentile, 1.4 – 6.7), 48 patients developed CRC. The median time from HT to CRC was 4.5 years (0.7 – 8.0) and the median age at CRC was 65 (55 – 71). The cumulative incidence, adjusting for competing mortality, was 0.68% (95%CI: 0.45%, 1.0%) at 5 years and 1.7% (95%CI: 1.2%, 2.4%) at 10 years (Figure 1), corresponding to an incidence rate of 170 cases per 100,000 patient-years, and did not differ between men and women (180 vs. 120; P=0.7). In comparison, all-cause mortality was 20% at 5 years and 38% at 10 years. Age at HT was not significantly associated with CRC risk (P=0.22); patients age <45 at HT experienced similar risk as patients ≥45 (Table 2). In comparison, the age-adjusted CRC rate in the US population for years 2016-2020 was 42 and 32 cases per 100,000 patient-years in men and women, respectively. Year of HT was not associated with CRC risk (P=0.69).

Conclusion

In this cohort of HT recipients, the absolute CRC risk was lower compared to previous reports that did not account for the competing risk of death. However, rates of CRC were much higher compared to the general population and did not differ by age at HT, suggesting that all HT patients should be screened for CRC regardless of age.