Did new treatments contribute to a decrease in melanoma deaths?

Melanoma is one of the most common cancers diagnosed in New Zealand, and New Zealand has one of the highest rates of melanoma incidence and mortality in the world. Monitoring by Environmental Health Intelligence NZ (EHINZ) has found a recent sharp decline in melanoma mortality rates in New Zealand. Since 2014 and 2015 (with 376 and 378 melanoma deaths, respectively), melanoma deaths have declined to 362 deaths in 2016, 308 deaths in 2017, and 296 deaths in 2018. We believe that two new PD-1 inhibitor drug treatments introduced in New Zealand in 2016-nivolumab (Opdivo, BMS) and pembrolizumab (Keytruda, MSD)-may have contributed to this decrease in melanoma mortality. Other factors are unlikely to have had such a major effect, with the drop unlikely due to random variation, and no major changes in melanoma registrations or melanoma thickness at diagnosis over the past decade. While our monitoring of the time trend is descriptive only, and cannot attribute causality, it does suggest a recent decrease in melanoma mortality rates at the population level. These national-level statistics reflect both what might be expected in the New Zealand situation with the introduction of PD-1 inhibitor treatments, based on clinical trials, and what oncologists are seeing at an individual level. Further studies could investigate this observational finding, to confirm whether PD-1 inhibitor drug treatments are having an impact on melanoma mortality and survival rates in New Zealand.