What is the incidence of a new cutaneous melanoma lesion after immunotherapy?

I am asked this fairly often.  Mostly by those who are just worrying and rarely by those who have lived it.  Here's the deal per this single center study of 2,251 melanoma patients treated with immunotherapy ~

Incidence of New Primary Cutaneous Melanoma in Patients With Metastatic Melanoma Treated With Immune Checkpoint Inhibitors: A Single-Center Cohort Study.  Nanda, Dusza, Navarrete-Dechent, et al. JAMA Dermatol.  Jan 2021.

Importance: The development of new primary cutaneous melanoma (CM) after starting immune checkpoint inhibitor (ICI) therapy is poorly characterized.

Objective: To determine the incidence of new CM in patients treated with ipilimumab, nivolumab, and/or pembrolizumab for metastatic melanoma.

Design, setting, and participants: Single-center, retrospective, observational cohort study using an institutional database to identify patients diagnosed with melanoma at a tertiary care cancer hospital in New York, New York.

Exposures: Ipilimumab, nivolumab, and/or pembrolizumab treatment for metastatic melanoma.

Main outcomes and measures: Primary outcomes were the incidence proportion, the incidence rate, and the 5-year cause-specific cumulative risk.

Results: A total of 2251 patients were included in the study; mean (SD) age at the time of ICI start was 62.8 years. The majority were male (63.8%), White (92.7%), and non-Hispanic (92.1%). Forty-two of 2251 patients who received ipilimumab, nivolumab, and/or pembrolizumab were diagnosed with 48 new CMs at a median (range) of 397.5 (39-2409) days after ICI initiation. The median age of affected patients at the time of ICI first dose was 66.5 years. The majority were male (66.7%), White (92.9%), and non-Hispanic (100.0%). There were no differences in age, sex, race, and ethnicity among patients who did and did not develop a new CM. Patients who developed a new CM were more likely to have a family history of melanoma (23.8% vs 16.3%). Most new CMs (n = 30, 62.5%) were diagnosed after the last date of ICI administration. Twenty-seven (56.3%) new CMs were in situ and 21 (43.8%) were invasive. Of the invasive CMs with a reported Breslow thickness (n = 20), the median (range) thickness was 0.4 (0.1-8.4) mm. The overall incidence proportion of new CM was 1.9% (1.4%-2.5%) and the incidence rate was 1103 cases per 100 000 person-years (815-1492). The 5-year cumulative cause-specific risk of new CM was 4.9%.

So, there you have it.  The chance of another cutaneous lesion is low.  Take me.  Cutaneous lesion, Stage IIIb in 2003.  Second cutaneous lesion in 2007.  Stage IV with brain and lung mets in April 2010.  Phase 1 nivo only 2 1/2 year trial begun in December 2010.  NO melanoma since.  But, we all know melanoma sucks great big green stinky hairy wizard balls.  Live large, but stay vigilant my peeps!

For what it's worth - c