LAUSR

Dear Editor, Although anal squamous cancer (ASC) remains a relatively rare disease, the rate is increasing by about 2% per year. In the metaanalysis by Clifford et al the incidence rate (IR) for ASC in solid organ transplant recipients (SOTR) was 13 per 100.000 person-years and increasing up to 49.6 in patients that were transplanted more than 10 years ago. The analysis was based on large population studies starting in the 70s and 80s of the previous century. As both the frequency of solid organ transplantation and graft survival have significantly increased since, the incidence of ASC after solid organ transplantation is likely to be rising in the upcoming decades. Recently, we noticed a cluster of patients with ASC after heart transplantation, and performed a retrospective observational study of solid organ transplant recipients diagnosed with anal squamous carcinoma. The database of patients with anal malignancies at our tertiary hospital with extensive transplantation activity (8430 solid organ were transplanted until the end of 2021) was searched for ASC. Between 1 January 2010 and 31 December, 2019 a total of 79 patients was identified with new diagnosis of ASC. Eight of them were solid organ transplant recipients and five had received a heart transplantation (Table 1). The incidence rate of ASC after heart transplantation was calculated to be 136 per 100.000 person-years, much higher than the previously published IR for SOTR and even higher than the IR in HIV-positive men who have sex with men (MSM). The fact that the incidence rate of ASC in SOTR seemed to increase over time after transplantation is strengthened by our observation that the diagnosis of ASC occurred on average 13.4 ± 5.2 years after heart transplantation. The mean age at the time of diagnosis was 60.7 ± 5.9 years, similar to the age of nontransplant patients with ACS (62.5 ± 11.8 years). The exact reason for this extremely high incidence rate remains unclear. Maybe the high median patient survival (currently more than 18 years in our center) and the concomitant long-lasting exposure to immunosuppressive medication, partially explains the high incidence rate of ASC after heart transplantation. The number of patients is unfortunately too small to examine the effect of underlying cardiac disease, type and levels of immunosuppressive therapy. Therefore, we would like to encourage other transplantation centers and/or