Melanoma, because of its lethality, is of great medical importance and its incidence has increased in several countries over the last 40 years.1–5 Risk factors are mainly associated with the Caucasian population submitted to ultraviolet radiation, as well as family history, presence of melanocytic nevi, and immunosuppression.2–5

A total of 106,110 new cases are estimated in the United States and 8,450 cases in Brazil for 2020, 4,200 in men and 4,250 in women.6 Melanoma morbidity rates reach 51.7 cases per 100,000 inhabitants in Australia, considered one of the highest rates worldwide.4

In the southern region of Brazil, melanoma skin cancer is more frequent when compared to the other regions of the country, for both sexes.6,7

The annual incidence rates of melanoma per 100,000 inhabitants estimated in the capitals of southern Brazil in 2019 by the National Cancer Institute (Instituto Nacional do Câncer [INCA]), were: 8.3 (male sex - M) and 7.39 (female sex - F) in Curitiba-PR, 6.84 (M) and 7 .94 (F) in Florianópolis-SC and 9.25 (M) and 10.12 (F) in Porto Alegre-RS, rates that are obviously underestimated in relation to Blumenau.6–8

In Brazil, data on the incidence coefficient of cutaneous melanoma are rare in municipalities, capitals, states, and in the country itself; they are very underestimated and require specific epidemiological studies.

The municipality of Blumenau is located in the northeast of the state of Santa Catarina, latitude 26°55′10″ south, longitude 49°03′58″, and altitude 21 meters from sea level.9 The Caucasian population of Blumenau, consisting mostly of German and Italian descendants with phototypes I and II according to the Fitzpatrick classification,8 is subject to intense radiation in the summer, with a UVB-Index between 11.5 and 13.0 according to the National Institute for Space Research (Instituto Nacional de Pesquisas Espaciais [INPE]) and very high according to the Environmental Protection Agency/Operational Satellites (EPA/NOOA) – United States of America, therefore, being exposed to key risk factors for melanoma.10

The aim of this 40-year retrospective study (1980‒2009,11 plus 2010‒2019) was to describe the epidemiological characteristics of cutaneous melanoma in Blumenau, presenting statistical data that can be used as reference for epidemiological studies and prevention in southern Brazil. The time length of the study allows for showing the impact of health education actions on the prevention and early treatment of cutaneous melanoma.

This is a retrospective, descriptive and cross-sectional study that collected 2,336 cases of primary cutaneous melanoma in the three pathological anatomy laboratories in the municipality: Laboratory of Cytology, Immunopathology and Pathological Anatomy (Laboratório de Citologia, Immunopatologia e Anatomia Pathológica [CIPAC] - between 1980 and 2019), BML (Laboratório Beatriz Moreira Leite) and Pathology - Diagnosis in Medicine.

The data collected in the protocol by the authors included characteristics of the patients (age, sex, tumor location) and histopathological aspects of the melanoma. As inclusion and exclusion criteria in the case review, only those from the municipality of Blumenau were considered and cases of patients residing in other municipalities were excluded, aiming at the fidelity of calculations of morbidity coefficients.

The incidence rates of cutaneous melanoma per 100,000 inhabitants for Blumenau were calculated based on the annual population between 1980 and 2019 estimated by the Brazilian Institute of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística [IBGE])9 and cases found annually so that they can be compared with the coefficients of other cities, states and countries. Data were entered and calculated in the Excel 2016 program, adding data from 2010 to 2019 to those published from 1980 to 2009 in the Brazilian Annals of Dermatology (Anais Brasileiros de Dermatologia).10 Chi-square, Mann-Whitney, Kruskal-Wallis (non-parametric test), and Dunn’s tests, and Spearman’s correlation were utilized. The study was approved by the Research Ethics Committee for Studies conducted in Human Beings of Universidade Regional de Blumenau according to CAAE (Certificate of Presentation of Ethical Appreciation): 42905821.2.0000.5370 and number of the Consubstantiated Opinion of the Ethics Committee: 4.580.124.

The number of cases of primary cutaneous melanoma identified between 1980 and 2019 was 2,336, 44% (n = 1078) in males and 56% (n = 1,258) in females.

Table 1 shows the annual overall incidence rates and rates by sex of primary cutaneous melanoma in the municipality of Blumenau between 1980 and 2019.11 The overall incidence rates of 42.2 (2011) and 44.26 (2018) cases per 100,000 inhabitants/year of primary cutaneous melanoma are highlighted, as well as the rates of 52.87 (2011) and 41.7 (2018)/100,000 inhabitants in the male sex (Table 1). The incidence rates in the female sex were 46.7/100,000 inhabitants in 2018 and 44 in 2013 (Table 1).

Table 2 shows an average of the incidence rates by groups of years and, as a result, it showed significance in the period from 2000 to 2004, in which the incidence of cutaneous melanoma was significantly higher in females, with p = 0.0279. No significance was identified in the other periods.

The age group with the highest numerical incidence was over 55 years old, with 57% of the cases (n = 1321), with 14.9% of the cases occurring under 39 years of age (n = 343), with 95% confidence (Table 3).

The Mann-Whitney test and Spearman’s correlation were used in Table 4, to verify the increase in the incidence coefficient in each period and along the age groups. Both tests belong to non-parametric statistics. The use of such statistics is justified, considering the rejection of the null hypothesis of the normality test (Shapiro-Wilks test), that is, according to the normality test performed, the data do not show a normal distribution model.

As a result of this inferential part, both in men and women, the incidence coefficient had a significant increase from 1980 to 2018. On the other hand, it showed a very strong correlation in the years 2008 and 2018, indicating a higher concentration of the number of cases in older age groups.

The incidence rate in the male sex reached 253 cases/100,000 inhabitants/year in the age group of 65 to 69 years in 2018 and 421 cases per 100,000 inhabitants in the age group ≥ 70 years. In the female sex, there were 128 cases/100,000 inhabitants/year in the age group of 65 to 69 years and 301 cases in the age group ≥ 70 years (2018) as shown in Table 4.

The most frequent histopathological types were superficial spreading melanoma with 64.5% (n = 996) between 1980 and 2019, followed by nodular melanoma with 22.8 (n = 353). Lentigo maligna melanoma reached 9.4% (n = 143) and acral lentiginous melanoma, 3.3% (n = 51; Table 5).

The distribution of the histopathological types according to sex showed a predominance of 68.5% (n = 569) of the superficial spreading type in women (p = 0.00050) and 60% in men (Table 5).

Table 6 shows the numerical and percentage distribution of cutaneous melanoma according to the primary location and sex, with a predominance of 49.5% (n = 366) of primary location on the trunk in men (p = 0.0001) and 35.3% (n = 267) in women.

Table 7 shows the percentage distribution of melanoma cases according to Clark level between 1980 and 1999, 2000 to 2009, and 2010 to 2019, highlighting the percentage increase in early diagnoses (Clark level I and II) of 24.95 % from 1980 to 1990 to 49.8% from 2010 to 2019. This means a 199.6% increase in early diagnoses from 2010 to 2019, when compared to the period 1980 to 1990.10 From 2010 to 2019, there was a significant increase in the number of melanoma cases in Clark levels 1 and 2 and in level 5, according to the Chi-square test. This increase can be better observed in Fig. 1.

Figure 1.

Numerical distribution of primary cutaneous melanoma, according to Clark level by decades: 1980 to 1990, 2000 to 2009 and 2010 to 2019; Blumenau-SC

(0.14MB).

Table 8 shows the percentage distribution of melanomas according to Breslow’s thickness index between 1995 and 1999,10 2000 and 2009,10 and from 2010 to 2019. Melanomas diagnosed with thickness < 1 mm reached 46.7% between 1995 and 199910 and increased to 63% between 2000 and 2009,10 reaching 58% between 2010 and 2019 (p = 0.000001).

The last period (2010‒2019) showed a significant increase in the percentage of cutaneous melanoma in the thickness categories from 0.0 to 0.5 mm and > 2.0 mm.

There was a 134% increase in the frequency of Breslow thickness between 0‒1 mm (early diagnosis) in the period 2000 and 200810 when compared to the period of 1995 to 1999 and 1918% of melanoma (in situ) < 0.5 mm in 2010 to 2019 (518 cases), when compared to 1995–1999 (27 cases) (p = 0.000001). Fig. 2 makes this increase in the percentage number of cases clearer. Therefore, it can be said that this increase was significant according to the Chi-square test.

Figure 2.

Distribution of the number of primary melanoma cases from 1995 to 1999, 2000 to 2009 and 2010 to 2019, Blumenau-SC

(0.22MB).

This study only considered histopathological reports with a definitive diagnosis of primary cutaneous melanoma; therefore, the data are underestimated, consequently resulting in lower rates than in reality, but high in relation to the incidence rates found in Brazil and worldwide.

The present study shows that the morbidity of cutaneous melanoma in the municipality of Blumenau increased from 4.4 (1980)11 to 44.26 cases per 100,000 inhabitants (Table 1), with a sharp increase in incidence, of around 1,000% in morbidity per 100,000 inhabitants compared to 1980.11

The world population-adjusted rates found were 25.86 melanoma cases per 100,000 inhabitants/year based on cases diagnosed between 1975‒2017 originating from 17 SEER geographic areas.12

As the incidence by age (SEER)12 was not performed and as there has been a gain in life expectancy in recent decades, part of the increase in diagnoses can be due to the extension of survival in the group of elderly people at higher risk.

The cutaneous melanoma morbidity coefficients found in Blumenau are close to those expected for European descendants (Germans and Italians), fair-skinned Caucasians living in a geographic region with a high level of ultraviolet radiation.1,3,12

The results found in this study can be used as reference for most municipalities in southern Brazil where there is intense solar radiation affecting the light-skinned population, with phototypes I and II, of European descent.

The increase in early diagnosis can be attributed to education and primary prevention campaigns, as reported in other countries,22–25 and carried out in Brazil by the Brazilian Society of Dermatology (Sociedade Brasileira de Dermatologia).

This 40-year epidemiological study concludes with the following observations:

From 1980 to 2019, the crude rate of melanoma increased from 4.4 cases11 to 44.26/100,000 inhabitants, with a peak of 46.73 in women and 52.87 in men and a predominance of melanoma incidence in the female sex, with 56% of cases (n = 1,258).

There was a higher incidence of melanoma in the age group over 50 (64.9%), with a peak ≥70 years, with 421.6 cases per 100,000 male inhabitants and 301 cases in females (2018). There was a predominance of the superficial spreading type, with 64.5% of cases (n = 996) followed by nodular melanoma with 22.8% (n = 353).

There was an increase in early diagnosis in the period 2000 to 2009,10 represented by 63% of diagnoses with Breslow thickness < 1 mm and 53% from 2010 to 2019.

A possible increase in survival21–25 of 199% according to Clark level is also verified in 2010 to 2019, compared to 1980 to 199011 and 113% of survival according to Breslow thickness in the 2010 to 2019 decade when compared to 1995 to 1999.10

The fatality rate represented by thick melanomas decreased from 75% of cases from 1980 to 199010 to 49% in the 2010 to 2019 decade.19,20

Considering the increased incidence, especially in the elderly, it is essential to maintain public awareness campaigns about the initial signs of melanoma, the ABCDE rule, care for family members, multiple nevi, and priority care for the elderly.

None declared.

Nilton Nasser: Design and planning of the study; data collection; writing of the manuscript and critical review of the content; preparation of tables, from 1980 to 2019; approval of the final version of the manuscript.

Joana Laurindo da Silva: Data collection, legal aspects of the study, such as approval by the Ethics Committee, literature search; help preparing the tables; approval of the final version of the manuscript.

Grazielle Corrêa: Data collection, data survey; help preparing the tables; approval of the final version of the manuscript.

None declared.