Skin cancer risk in more than 200 000 patients with haematological malignancies over 30 years: a nationwide population-based study in the Netherlands.

Background: Patients with haematological malignancies are at increased risk of developing skin cancer and often experience worse skin cancer-related outcomes. However, there is a lack of nationwide, population-based data with long-term follow-up on the incidence and risks of different skin cancer types across all haematological malignancies.

Objectives: To assess population-based risk estimates for cutaneous squamous cell carcinoma (cSCC), malignant melanoma (MM), Merkel cell carcinoma (MCC) and basal cell carcinoma (BCC) among patients with haematological malignancies, stratified by skin cancer type and haematological malignancy subgroup. These estimates can serve as a base for surveillance guidelines and patient education.

Methods: This nationwide population-based epidemiological cohort study used data from 210 794 patients diagnosed with a haematological malignancy between 1989 and 2020 from the Netherlands Cancer Registry (NCR). In addition, data on each type of histopathologically confirmed skin cancer per patient after haematological malignancy diagnosis were retrieved from the NCR. Patients with a history of skin cancer prior to their haematological malignancy were excluded. Cumulative incidences, standardized incidence ratios (SIRs) and absolute excess risks for each of the four skin cancers were calculated and stratified by haematological malignancy subgroup, age, sex, follow-up and primary treatment.

Results: The overall 10-year cumulative incidence of developing a first skin cancer was 2.6% for cSCC, 0.5% for MM, 0.05% for MCC and 4.8% for BCC. Compared with the general population, nearly all haematological malignancy subgroups showed more than a twofold increased risk of cSCC, MM, MCC and BCC. Patients with chronic lymphocytic leukaemia (CLL) showed the highest risks for each of the four skin cancers, with SIRs of 4.4 for cSCC, 2.7 for MM, 9.3 for MCC, and 2.6 for BCC. These elevated risks persisted for > 30 years after haematological malignancy diagnosis.

Conclusions: Patients with all types of haematological malignancies, and especially those with CLL, have a lifetime increased risk of developing different types of skin cancer. These findings highlight the importance of creating awareness among patients and care providers about this increased risk and promoting sun-protective measures and regular skin self-examinations in this high-risk population.