BI12 How should we manage transplant recipients after a first cutaneous squamous cell carcinoma? An update from the UK COAST (Contemporary Outcomes After cutaneous SCC in Transplant recipients) study

After first cutaneous squamous cell carcinoma (cSCC), up to 75% of kidney transplant recipients (KTRs) will develop further cSCC and their risk of metastasis is increased. Evidence is limited regarding which secondary prevention strategies (including modification of immunosuppression, and systemic and topical chemoprevention) are currently being undertaken in transplant centres across the UK. To address this, the UK COAST (Contemporary Outcomes After cutaneous SCC in Transplant recipients) multicentre retrospective cohort study is evaluating management after first cSCC in KTRs. Adult KTRs (n = 139) with a first-ever cSCC during the period from January 2016 to December 2020 were identified using medical records from eight centres, with follow-up data collected to December 2022 [median follow-up 39 months, interquartile range (IQR) 27–54]. Data were collected on outcomes of interest (further malignancies, graft loss and death). The cumulative duration of immunosuppression at first cSCC was 136 months (IQR 72–200); the median age was 63 years (IQR 57–72); 49% of KTRs had a history of actinic keratosis (AK), 28% had cSCC in situ, 32% had other skin cancer and 8% had noncutaneous malignancies. The first cSCC was high risk (HR) in 25% based on the American Joint Committee on Cancer staging criteria (8th edition), 14% by Brigham and Women’s Hospital criteria, and 75% by the British Association of Dermatologists’ 2020 cSCC guidelines criteria. Overall, 4% had > 10% 5-year risk of metastasis using a newly published clinicopathological risk calculator. Within 6 months of the first cSCC, systemic (acitretin or nicotinamide) and topical (mainly 5-fluorouracil) chemoprevention were started in 5% and 19% of patients, respectively. A total of 5% underwent destructive therapies including cryotherapy. Immunosuppression reduction (IR) was undertaken in 40 of 131 patients (31%), with cSCC as the stated reason in 63%. IR was significantly more common with HR-cSCC, incomplete histological margins and perineural invasion (P < 0.05). Overall, 49% of patients developed further cSCCs (at median 14 months after first cSCC, IQR 9–27), 12.2% metastatic cSCC (11 months, IQR 6–13), and 8% other malignancies. In total, 14% of patients experienced graft loss (median 32 months, IQR 20–44) and 30% died (median 23 months, IQR 12–34), with cSCC-specific death in 9.4%. On multivariate adjustment, male sex, previous AK, cSCC in situ, previous basal cell carcinoma and HR-cSCC were associated wi