Trends in Incidence of Cutaneous Malignant Melanoma in Canada: 1992-2010 versus 2011-2015.

To the Editor: The incidence of cutaneous malignant melanoma (CMM) worldwide continues to rise.1Sacchetto L. Zanetti R. Comber H. et al.Trends in incidence of thick, thin and in situ melanoma in Europe.Eur J Cancer. 2018; 92: 108-118Abstract Full Text Full Text PDF PubMed Scopus (108) Google Scholar We recently reported a comprehensive, population-based study of CMM in Canada during 1992-2010 and demonstrated a steady increase in its incidence across the Canadian provinces and territories, with a slight male predominance. Geographically, the highest CMM incidence rates were documented in the provinces of Nova Scotia and Prince Edward Island.2Ghazawi F.M. Cyr J. Darwich R. et al.Cutaneous malignant melanoma incidence and mortality trends in Canada: a comprehensive population-based study.J Am Acad Dermatol. 2019; 80: 448-459Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar We extended this study and examined data on CMM incidence by using the Canadian Cancer Registry (2015 version) for the years 2011 to 2015 for all Canadian provinces except Quebec by using the International Classification of Diseases for Oncology, Third Edition, codes for all CMM subtypes, in a manner similar to that previously reported2Ghazawi F.M. Cyr J. Darwich R. et al.Cutaneous malignant melanoma incidence and mortality trends in Canada: a comprehensive population-based study.J Am Acad Dermatol. 2019; 80: 448-459Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar; we identified 27,095 patients (Table I). Consistent with the previously reported trends,2Ghazawi F.M. Cyr J. Darwich R. et al.Cutaneous malignant melanoma incidence and mortality trends in Canada: a comprehensive population-based study.J Am Acad Dermatol. 2019; 80: 448-459Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar this malignancy had a higher age-standardized incidence in males (23.2 cases per 100,000 in males per year vs 17.7 in females) . The mean age of diagnosis was 64.9 ± 14.7 years for males and 60.4 ± 18.8 years for females (62.8 ± 16.8 years for both sexes during 2011-2015 versus 58.5 ± 21.6 during 1992-2010) (Table II). Age range analysis confirmed these findings and showed that 60.3% of patients with CMM in Canada during the period from 2011 to 2015 were age 60 years or older (vs 48.7% in 1992-2010) (Table I), with an overall increased percentage of the Canadian population older than 60 years in 2011-2015 (20.8% vs 17.4% in 1992-2010). This finding suggests that increasing age of the population contributes significantly to the increasing incidence of CMM.Table IClinical characteristics of CMM patients in Canada that were diagnosed in 2011-2015MalesFemalesBoth sexesCharacteristicn∗Rounded to a multiple of 5.%n∗Rounded to a multiple of 5.%n∗Rounded to a multiple of 5.%Age, y0-19250.17500.40750.2820-398305.68144011.5422758.3940-59400027.36441535.38841531.0560-79725549.62479538.4212,05044.46>80249517.07178014.26428515.81LocationSkin of the lip150.10250.20350.13Eyelid450.31400.32850.31External part of the ear5603.831351.086952.57Skin of other parts of the face156010.6710658.5326259.69Skin of the scalp and neck13209.034403.5317606.50Skin of the trunk570539.02277022.20847031.26Skin of the upper limb and shoulder323522.13359028.77682525.19Skin of the lower limb and hip14609.99395531.69541519.99Overlapping lesion of skin700.48300.241050.39Skin, not otherwise specified6504.454303.4510803.99Total14,61510012,48010027,095100Age and anatomic distribution analysis is presented for males and females.CMM, Cutaneous malignant melanoma.∗ Rounded to a multiple of 5. Open table in a new tab Age and anatomic distribution analysis is presented for males and females. CMM, Cutaneous malignant melanoma. Analysis of the anatomic location of CMM in 2011-2015 revealed trends similar to those in 1992-2010, where the majority (63%) of CMMs in males developed on the head and trunk, however, in females, the lower extremities were preferentially affected and accounted for 31.7% of cases (Table I), further highlighting differences in sun exposure behaviors as possible contributing factors for these findings. The age-standardized CMM incidence rate in Canada in 2011-2015 was 20.06 cases per 100,000 individuals per year (95% confidence interval, 19.82-20.30), as compared with the 1992-2010 rate of 12.27 (95% confidence interval, 12.18-12.36), demonstrating an ongoing steady increase. Age-standardized CMM incidence was highest in the province of Prince Edward Island, followed by Nova Scotia. The incidence rates for all provinces and territories are summarized in Table II. These findings highlight a consistent trend of increasing CMM incidence in Canada with the expected north-to-south gradient. Several factors may contribute to the high incidence of CMM in Prince Edward Island, including the province's aging population, proportion of individuals with Fitzpatrick type skin I to III, and relative abundance of water and sand (which are known to have increased surface reflection of ultraviolet radiation in comparison with that of grass).3Chadysiene R. Girgzdys A. Ultraviolet radiation albedo of natural surfaces.J Environ Eng Landscape Management. 2008; 16: 83-88Google Scholar Finally, analysis of CMM incidence by age group confirmed that the incidence increases with age, with important sex differences for each age category (Table I).Table IICMM incidence rates and mean age at diagnosis across the Canadian provinces (except Quebec) and the territories during the periods 1992-2010 and 2011-2015Province1992-20102011-2015Age-adjusted incidence rate per 100,000 person-years (95% CI)Mean age at diagnosis, y (SD)Age-adjusted incidence rate per 100,000 person-years (95% CI)Mean age at diagnosis, y (SD)Prince Edward Island18.89 (17.22-20.56)60.00 (16.33)28.59 (24.84-32.34)62.27 (14.84)Nova Scotia18.03 (17.42-18.64)59.28 (16.23)26.37 (24.97-27.77)61.95 (15.17)Ontario14.28 (14.12-14.43)59.33 (26.45)21.42 (21.07-21.76)63.40 (17.76)British Columbia14.96 (14.69-15.23)58.24 (16.84)19.82 (19.26-20.38)63.11 (15.65)New Brunswick14.45 (13.83-15.06)58.35 (16.55)19.27 (17.94-20.60)62.88 (15.21)Alberta13.13 (12.82-13.44)55.84 (17.1)17.31 (16.69-17.94)60.4 (15.88)Newfoundland and Labrador10.37 (9.75-11.00)57.76 (16.86)16.32 (14.84-17.79)60.09 (15.22)Manitoba10.95 (10.51-11.39)59.38 (17.44)15.96 (14.96-16.97)63.40 (15.73)Saskatchewan11.60 (11.11-12.08)59.65 (17.23)14.43 (13.40-15.45)62.02 (15.98)Northern territories (Northwest Territories, Nunavut, and Yukon)5.92 (4.60-7.24)48.53 (13.33)6.54 (4.14-8.95)56.13 (9.26)Canada12.27 (12.18-12.36)58.50 (21.6)20.06 (19.82-20.30)62.81 (16.83)Age-standardized incidence rates are per 100,000 person-years.CI, Confidence interval; SD, standard deviation. Open table in a new tab Age-standardized incidence rates are per 100,000 person-years. CI, Confidence interval; SD, standard deviation. The observed trends of increasing CMM incidence in the aforementioned preferential anatomic sites in men versus in women and differences in incidence rates across Canada further highlight the continuity of the aforementioned trends2Ghazawi F.M. Cyr J. Darwich R. et al.Cutaneous malignant melanoma incidence and mortality trends in Canada: a comprehensive population-based study.J Am Acad Dermatol. 2019; 80: 448-459Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar and emphasize important sex- and age-specific differences in the incidence of melanoma. To decrease CMM incidence, stronger targeted public health efforts must be made. Specifically, we must strive to improve patient education in Canada and address sex-specific sun-seeking habits and exposures. We thank all the staff that administer the data registries included in this analysis. The interpretation, analysis, and reporting of these data are the sole responsibility of the authors.