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Print version ISSN 0365-0596
On-line version ISSN 1806-4841
An. Bras. Dermatol. vol.79 no.6 Rio de Janeiro Nov./Dec. 2004
CLINICAL, EPIDEMOLOGICAL, LABORATORY AND THERAPEUTIC INVESTIGATION
Epidemiology of squamous cell cancers in Blumenau -SC-Brazil, from 1980 to 1999*
Ph.D. in Dermatology - Federal University of Rio de Janeiro, Dermatology specialist - SBD, and titular professor of Dermatology at the Regional University of Blumenau Medical School
BACKGROUND: The morbidity from skin squamous
cell cancers is increasing worldwide. In Brazil there are no studies on the
morbidity coefficients for this type of cancer.
OBJECTIVES: To determine the morbidity coefficients, analyze and classify the squamous cell cancers diagnosed in the city of Blumenau-SC-Brazil, from 1980 to 1999, according to their most important clinical and histologic features.
METHODS: The author reviewed the histopathological exams at two laboratories in the city of Blumenau, with respect to sex, age, anatomical site and histologic type. The morbidity coefficients were calculated using the number of squamous cell cancers found and estimated annual population.
RESULTS: We identified 2,195 tumors, with a higher incidence in males and individuals over 60 years of age. Regarding the anatomical site, we found more tumors in sun exposed areas. The morbidity coefficients varied from 31.1 cases per 100,000 inhabitants/year in 1980 to 86.3 cases per 100,000 inhabitants in 1989.
CONCLUSIONS: Squamous cell cancers in Blumenau present similar patterns of distribution according to age, anatomical site and histological types as the world literature and the coefficients of morbidity were the only ones found in the Brazilian literature consulted.
Key-words: carcinoma, squamous cell; epidemiology; morbidity; neoplasms.
Squamous cell cancers rank second place in the incidence of malignant skin tumors, appearing in all the statistics as being responsible for approximately 20% of their total.1,2,3
This is the most common tumor in older patients and it is often the result of cumulative solar radiation during a lifetime. Other causal agents, however, can induce squamous cell cancers.4-7
Due to their high incidence, studies into their type, degree of involvement and epidemiology are important for the prevention and early treatment of these tumors.
The vital statistics are focused on diseases that are almost always fatal and do not include much data on non-melanoma skin cancers: basal cell cancers and squamous cell cancers. There are practically no records of basic populational measures on the morbidity of these cancers in the world literature, since squamous cell cancers appear in the statistics together with basal cell cancers and are classified as non-melanoma skin cancers.8
Scotto, Fears & Fraumeni, in 1983, found 233 cases of non-melanoma cancers per 100,000 inhabitants/year, without specifying the relative coefficients for the basal cell and squamous cell carcinomas.2
It was expected that during 1994, 900,000 to 1,200,000 people would develop non-melanoma skin cancers in the United States of America.9
In the North of Australia the morbidity coefficients for non-melanoma cancers varied from 1,000 to 2,000 cases/100,000 inhabitants/year between 1988 and 1990.10-13 There was an increase to the order of 51% in the number of cases of squamous cell cancers between 1985 and 1990.14
In this work, the squamous cell cancers diagnosed in Blumenau, from 1980 to 1999, were analyzed according to the main clinical and histological characteristics, taking into account the variables of sex, age, anatomical site and histological types. The morbidity coefficients for squamous cell cancers were calculated for the period between 1980 and 1999, however, they should be considered an underestimate, since only data from anatomic pathological exams were used, and clinical cases that were not confirmed by laboratory tests were excluded.
The results found revealed hitherto unpublished data for Brazil and serve as a reference for almost the entire South Region of the Country, given that the predominant population is Caucasian and exposed to a great intensity of ultraviolet radiation.
MATERIAL AND METHODS
The morbidity coefficients for squamous cell cancers in Blumenau were calculated based on the annual population from 1980 to 1999, as estimated by the Brazilian Institute of Geography and Statistics (IBGE)15 and a review of the cases diagnosed by histopathological analysis at the pathological anatomy laboratories of the city, Laboratory of Cytology, Immunopathology and Pathological Anatomy (Cipac) and Laboratory Beatriz Moreira Leite (BML Pathology), from 1980 to 1999, for a total of 2,195 cases of squamous cell cancers. In the selection of cases, only those originating from the Municipal district of Blumenau were considered for greater accuracy in the calculation of the morbidity coefficient.
A total of 2,195 primary cases of squamous cell cancers were found in the records kept at the pathological anatomy laboratories in the municipal district of Blumenau, SC.
The distribution according to sex was 1,320 (60.1%) cases involving males and 875 (39.9%) involving females.
The morbidity coefficients per 100,000 inhabitants/year relative to squamous cell cancers, from 1980 to 1999, are presented in table 1.
Table 2 shows the coefficients of morbidity for squamous cell cancers according to sex. It is notable that there was a significant difference between the incidence (about 20% more) in the male sex in relation to females.
The age varied from 19 to 86 years, and the distribution according to age group shows a higher percentage of tumors among those over 60 years of age (Table 3).
Table 4 presents the percentage of squamous cell cancers according to the anatomical site in the skin: 47% of the cases were found in the face, reaching a total of 78% in the head and the remaining 22% of the cases were in the trunk and limbs.
It should be observed that the incidence of squamous cell skin cancers found in the ears reaches 85% in men and only 15% in women.
The squamous cell cancers found in the lower lip appear with a very much higher frequency in men (87%) compared to women (13%).
Table 5 shows the percentage of squamous cell cancers according to the degree of involvement found in the study: well differentiated, with 72.3% of the cases; moderately differentiated in 19.1%; and slightly differentiated amounted to 5.9% of the cases and in situ (Bowen), 2.7%.
In the case of squamous cell cancers with "well differentiated" degrees, a great frequency is observed in the face, pre-auricular region (23%) and highly differentiated between the sexes, with the greatest in males, ear (90.5%) and lower lip (84%).
With reference to the "moderately differentiated" squamous cell cancers, it can be noted that 100% of the cases located in the lower lip corresponded to the male sex.
During the 20-year period, 2,195 cases were diagnosed by histopathological method. However, since these are absolute numbers they can not be compared with other absolute numbers found in national and foreign studies.
The morbidity coefficients were then were calculated per 100,000 inhabitants/year, which allowed a comparison with other coefficients, until now national coefficients were nonexistent, but foreign coefficients, especially those regarding Australia and the United States of America are available.16
The data of this study does not enable, however, specific comparison with data from these countries, because their coefficients are not based on a differentiation between non-melanoma cancers and squamous cell cancers. The coefficients obtained here are very much lower than those found in Australia since that country has an efficient registration system for cases of skin cancer.17
The morbidity coefficients allow an evaluation of the increase or decrease in the incidence of squamous cell cancer as well as others, such as basal cell and malignant melanoma.
In this study, relative to the period between 1980 and 1999, a decrease was detected in the incidence from 1989 to 1996, of 86.3 to 35.9 cases per 100,000 inhabitants. Starting from 1997 and up to 1999, there was a gradual increase, from 30.5 to 43.8 cases per 100,000 inhabitants a year.
This decrease can be attributed to the impact of health education among the population for preventive measures using sunscreen by national and local campaigns, led in Brazil by the Brazilian Society of Dermatology, from 1985 to 1999. There could also have been a loss of patients with skin cancer to other municipal districts and neighboring states or a decrease in the number of anatomic pathological exams which were the numeric basis of this study.
The national and international literature shows that squamous cell cancer is more frequent in men than in women, affecting almost twice as many men.18,19,20
We found that 60.1% of the squamous cell cancers involved men, against 39.9% in women, a result compatible with the world and national literature.18,19,20
The incidence of non-melanoma cancers increases significantly with age, especially squamous cell cancers,16 which in Blumenau were found in 63.7% of the population over 60 years of age and in only 18.3% below 50 years of age. No case was registered below 18 years, confirming the rarity of its occurrence during childhood and adolescence.
Prado (1987) found 311 cases of squamous cell cancers in a study in the State of Piaui, Brazil, and of these, 51.4% occurred in patients over 60 years of age.19
The majority of squamous cell cancers were found in sun exposed areas (78%): head, face and neck (Table 4), corroborating the world literature consulted.16,21,22,23
Sun exposed areas in men show a much higher incidence than covered areas in women: 85% of the cases of squamous cell skin cancer found in the ears were presented by men against 15% by women, which is due to an important epidemiologic factor: the length of the hair which covers ears in females, or in other words, a natural protection against ultraviolet radiation, the main causal factor in the genesis of these tumors.16,18,21,22,23
It should be underscored that squamous cell cancers tend to develop in areas with prior inflammation or scars.16
It is noteworthy that (Table 4) squamous cell cancer is much more common in the lips of men than in women (87% against 13%), probably associated to the habit of smoking, which increases the risk for this type of skin cancer, according to statistics24 over the last eight years. However, it should be kept in mind that the use of lipstick by women represents an excellent protection against ultraviolet radiation and could constitute an important epidemiologic factor in the prevention of this cancer in the lower lip of women.
The population studied, resident in the municipal district of Blumenau, SC, Brazil, is mostly Caucasian, descendent of Germans and Italians from the north of Italy; therefore, skin types I and II (according to Fitzpatrick) are most found.
The ultraviolet radiation incidence on the population of Blumenau, as measured by the National Institute of Space Research (INPE) during the summer, has a UVB-index of 11.5, higher than other Brazilian cities closer to the Equator (Table 8) and is considered very high, as shown in table 9.
Ultraviolet radiation is the most important risk factor.16 Squamous cell cancers are due to the cumulative solar radiation, unlike basal cell cancers that are caused by intermittent solar radiation, particularly among people under 40 years of age, according to Karagas in 1994.18
The risk of developing squamous cell cancer is greater among white individuals, with difficulty in tanning, tendency to sunburns, light hair and blue eyes.4,8,11,18,22,25,26
The greater the UVB radiation, the greater the incidence of skin cancer, and this radiation also depends on the ozone layer, which filters out the ultraviolet radiation.25-28
In the sample of 2,159 cases of primary squamous cell cancers diagnosed over a period of 20 years and with the determination of the annual morbidity coefficients, it was possible to verify:
1. in the last few years there has been an increase in the morbidity coefficients;
2. a relevant male prevalence;
3. greater incidence over 60 years of age and absence under 18 years of age;
4. anatomical site predominantly in sun exposed areas;
5. greater frequency of cases with a "well differentiated" degree of involvement.
According to the data found in this study, it was concluded that the population of Blumenau, predominantly white with skin types I or II and exposed to intense solar radiation presents a great risk for developing squamous cell cancers.
These tumors constitute a public health problem in the Municipal District of Blumenau, indicating the need for various programs in the field of the Sanitary Education for prevention, diagnosis and early treatment of the disease, thereby increasing the cure rate and avoiding more advanced cases that can present metastasis.
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89010-030 Blumenau SC
Tel./Fax: (47) 322-3143
Received on January 05, 2004
Approved by the Consultive Council and accepted for publication on November 01, 2004
* Work done at the Regional University of Blumenau.