Skin cancer is a multifactorial disease that results mainly from genetic alterations, environmental factors and life style.1Basal cell carcinoma (BCC) is the most common human neoplasm and its incidence has been increasing in all countries at a rate of 3 to 7% per year, configuring a public health problem.2,3In Brazil, among all malignant tumors, skin cancer appears with the highest incidence.4

Squamous cell carcinoma (SCC) is the second most common skin cancer and is classified as a nonmelanoma skin cancer, as basal cell carcinoma; together they correspond to 95% of all malignant skin tumors.5,6 Despite the existence of still unknown risk factors in the genesis of nonmelanoma skin cancers, their relationship with chronic sun exposure has been proven.7,8

In general, most skin cancers have a good prognosis, with cure rates above 95% of the cases when diagnosed early and adequately treated.9 However, cutaneous melanoma, a tumor arising from melanocytes, deserves attention in this context due to its high metastatic potential and mortality.9-12

Statistical data from the National Cancer Institute, 2016, revealed an estimated 175,760 new cases of nonmelanoma skin cancers, with 80,850 of those in males and 94,910 in females, besides 5,670 new cases of cutaneous melanoma for the same period. This confirms the relevance of statistical analyses for primary skin tumors because they provide epidemiological tools useful in the identification of risk subgroups and in the promotion of prevention as a unique strategy in this context.

This is an epidemiological, descriptive and retrospective study, conducted based on the manual analysis of histopathology files of a university hospital in Campos dos Goytacazes, State of Rio de Janeiro. The objective of the study were malignant skin neoplasms, basal cell and squamous carcinomas and cutaneous melanoma in particular. The data collected were initially grouped into plain Microsoft Excel spreadsheets and subsequently converted into graphic designs by the Sistema de Análises Estatísticas e Genéticas – SAEG, version 9.1.

Histopathology reports of incisional and excisional skin biopsies performed by dermatologists, general and plastic surgeons in our service and other smaller institutions that have us as a reference, as well as a small amount of samples collected in clinics and private practices from January 2013 to December 2015 were analyzed. In total, 2,207 files were evaluated by dermatology residents in approximately 44 hours.

In regard to the items proposed for the explanation of this study, we selected: age group (in decades), gender, period to be analyzed (in years) as well as the types of skin cancer, if basal cell or squamous cell carcinoma or melanoma, with all other excluded from the sample. The affected anatomical site was also addressed in this study and defined in seven areas of interest, namely: scalp, face, cervical region, upper limbs, lower limbs, trunk and genital region, of which the first five were listed as photoexposed.

Of the 2,207 histopathological reports analyzed, a sample of 306 cases (13.86%) represented the skin cancers selected for this study. Of those, 232 cases of BCC (75.9%), 55 of SCC (18.0%), and 19 of cutaneous melanomas (6.5%) were registered and the ratio of 1 malignant skin neoplasm for each 7.21 files reviewed was found (Graph 1).

Graph 1.

Prevalence of cutaneous neoplasms by subtype and anatomical distribution

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Overall, the involvement of anatomical sites was varied, with most cases occurring on the face (58.8%), followed by the trunk with 18.7%, and lastly by the lesions diagnosed on the scalp, with only 1.7%. Upper limbs, lower limbs, cervical and genital region were also affected, but in lower proportions (Graph 1).

The temporal analysis of the study shown on graph 2 revealed a decrease in the incidence of 3.4% and 5.4% from the first to the second year (2014) and from that to the third (2015), respectively. It was also observed in the same display that females (51.0%) were slightly more affected than males (49.0%) and that the incidence increases linearly from the fourth to the seventh decade of life, where most cases were registered (27.6%). Only 9.4% of the patients were elderly, aged 80 years or older.

Graph 2.

Distribution of malignant cutaneous neoplasms according to the timeline of the study (in years), gender and age group

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The cross-sectional view of this study, considering its start and finish (first and third years), revealed a 10.1% increase in the number of new BCC cases and 3.8% for melanoma, that achieved a percentage almost twice as high in this period. In contrast, there was a linear decrease in SCC cases for less than half (14.8%) from 2013 to 2015.

In regard to the development of nonmelanocytic tumors on photoexposed areas, BCC was the most prevalent, with more than 85% of the cases diagnosed in areas submitted to actinic effect, and the face was the most affected area (69.5%). Similarly, 67.9% of all SCCs also appeared on sun exposed skin and the face (30.5%) was again the most affected site. Cutaneous melanoma presented an inversion of this pattern: 68.4% were excised from areas commonly sun protected, as shown in graph 3.

Graph 3.

Prevalence of cutaneous tumors in photoexposed and non-photoexposed areas

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Still regarding the body areas involved, the prevalence of BCC and SCC were similar since both affected the face and trunk as the preferred sites; the latter was also the most affected area by cutaneous melanomas (63.2%). Virtually all tumors diagnosed on the scalp (3.8%) were SCC and no melanoma was found on this site (Graph 4).

Graph 4.

Cutaneous neoplasms according to the type and most commonly involved body areas

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The study sample reveals, although superficially, the epidemiological profile of the most common types of skin cancer with a retrospective analysis of a university hospital in Campos dos Goytacazes and surroundings. At the time of the research, it can be said that the institution had a reference role for many local services because it is the only service in the city with a practicing dermatopathologist, absorbing simple and particularly clinically atypical cases, what makes this analysis a potential mirror of the reality.

As announced by the broad existing literature on the prevalence of malignant skin tumors, BCC is the most frequent subtype and corresponds to 70-80% of all cases.13 Data from this study confirm general statistics with 232 BCC cases (75.9%) and reaffirm the expected ration of four to five BCCs to each SCC.14 For each melanoma, 11.6 BCCs were reported, datum that is also consistent with the literature and determines an approximate ratio of ten BCCs for each melanoma.14

The decrease in the overall incidence of skin cancers in the period analyzed was due to the decrease in number of SCCs. This event is partially related to the improved approach to pre-cancerous lesions, particularly actinic keratoses, and also in situ neoplasms (Bowen’s disease), with the comprehensive use of cryotherapy in our service over the past six to seven years. It is well known that cryotherapy with liquid nitrogen is a destructive procedure and highly effective, with cure rates between 75 and 99%.15

The age group with highest incidence of BCC was older than 80 years (80.7%). More than half of BCC cases occurs between 50 and 80 years and its incidence increases with advancing age.13 It is also expected, as seen in this study, a higher involvement in males than females, probably due to professional reasons linked to excessive sun exposure. 16

The prevalence of nonmelanocytic tumors in photoexposed areas confirms the important role of ultraviolet radiation in the genesis of these neoplasms and, in general, it is believed that for melanoma personal or family history represents the most important risk factor.4,17 In this investigation, the higher number of melanomas diagnosed in photo protected areas (68.4%) goes against this rationale and endorses the epidemiology published by Kraemer in 1994, in a study of 5,884 melanoma cases, of which 55% had a primary site on non-photoexposed areas and 45% in photoexposed areas.10

Retrospective statistical studies are a major tool for the detection of regional profiles of tumor involvement and facilitate the study and criticism of diagnostic and therapeutic methods present in a certain region or service. By enabling the epidemiological analysis of skin tumors in our region, detailed by gender, age group, anatomical site, subtype of cutaneous neoplasm and incidence variation over the years, this study substantiates the development of new actions of promotion of health and enable possible populational interventions better oriented and targeted.

Financial support: None.

Conflict of interest: None.