BI14 Nicotinamide prescribing for skin cancer chemoprevention: the Irish experience
Authors: Quigley Claire , Hanley Geoffrey , Moloney Fergal 
Published: June 2024

Abstract
In recent years there has been much discussion and exploration for a chemopreventive agent for skin cancer. This is something of particular interest for our transplant patients, who are at high risk of developing skin cancers, particularly keratinocyte cancers (KCs). Previous studies have highlighted benefit in immune-competent patients. A recent study by Allen et al. (Allen NC, Martin AJ, Snaider VA et al. Nicotinamide for skin-cancer chemoprevention in transplant recipients. N Engl J Med 2023; 388: 804–12) sought to investigate whether oral nicotinamide supplementation in organ transplant recipients provided any benefit. Their study demonstrated a 24% reduction in invasive SCCs in the nicotinamide group, but overall did not demonstrate a statistically significant reduction in KCs or precursor lesions. Some have challenged that the outcome of this trial will define future chemoprevention practices. We aimed to better define nicotinamide prescribing by surveying all members of the Irish Association of Dermatologists with a 13-item questionnaire focusing on barriers to and thresholds for prescribing oral nicotinamide chemoprevention. We asked respondents how often they prescribe oral nicotinamide for chemo­prevention for the following indications: (i) ‘A patient with sun-damaged skin but no focal actinic keratosis’, (ii) ‘Patient with focal actinic keratosis but no history of KC’, (iii) ‘Patient with field actinic change but no history of KC’, (iv) ‘At the time of diagnosis of first KC’ and (v) ‘Patient with more than one KC’. We applied these scenarios for both immunocompetent and immunosuppressed patients. In total, 81% of respondents reported that they prescribe oral nicotinamide for KC chemoprevention. For all chemoprevention indications, we found increased nicotinamide prescribing for immunosuppressed patients. The majority of nicotinamide prescribers introduce treatment in immunocompetent patients at the time of first KC diagnosis (48%) and prescribed oral nicotinamide ‘often’ if the patient had more than one KC (55%). For the same indications in the immunosuppressed cohort, rates of prescribing were 62.5% and 69%, respectively. For secondary chemoprevention, prescribing of nicotinamide (67%) is favoured over acitretin (20%) or a combination of both (11%) in patients at highest KC risk. Overall, 20% of respondents do not prescribe nicotinamide, citing the following reasons as barriers: lack of evidence (50%), cost to patient (22%) and lack of availability (14%). Closer surveillance and changing immunosuppressive protocols reducing skin cancer risk make it difficult to distil the chemopreventive effects of nicotinamide. Our study highlights high current rates of oral nicotinamide prescribing among Irish dermatologists, as secondary chemoprevention particularly in immunosuppressed patients. This baseline will allow for monitoring of potential future changes to skin cancer chemopreventive prescribing patterns among dermatologists. The use of nicotinamide, a drug with a well-established safety profile and favourable price point, warrants further studies before its chemopreventive potential is discounted.