A 10-year retrospective cohort study of ruxolitinib and association with nonmelanoma skin cancer in patients with polycythemia vera and myelofibrosis.

Background: Clinical trials report occurrence of nonmelanoma skin cancers (NMSCs) with ruxolitinib in patients with polycythemia vera (PV) or myelofibrosis (MF); however, the level of risk and effect of covariates are not known in the real-world setting.

Objective: To systematically assess the risk of developing NMSC after ruxolitinib exposure in patients with PV or MF.

Methods: A 10-year retrospective cohort of patients with PV or MF at Stanford Medical Center was identified and matched according to age, gender, race, Charlson Comorbidity Index, disease diagnosis, and follow-up time. The main outcome measure was hazard ratio (HR) for NMSC (comprised of basal cell carcinoma and squamous cell carcinoma [SCC]) after ruxolitinib exposure, adjusted for covariates.

Results: The study cohort consisted of 564 patients (188 exposed to ruxolitinib for at least 4 weeks, 376 unexposed). Ruxolitinib-exposed patients with PV or MF had an adjusted NMSC HR of 2.69 (95% CI, 1.03-7.02). In particular, ruxolitinib exposure was associated with SCC (HR, 3.24; 95% CI, 1.45-7.22), with non-Janus kinase 2-mutated patients showing even higher SCC risk (HR, 7.40; 95% CI, 2.54-21.63).

Limitations: Retrospective design.

Conclusions: Our real-world results indicate that SCC risk is increased in patients with PV or MF taking ruxolitinib and support consideration of skin cancer monitoring.