Risk factors for basal cell carcinoma: a case-control study

Marcus Maia,Nelson Guimarães Proença,José Cássio De Moraes

doi:10.1590/s0034-89101995000100006

Abstract

A controlled trial was performed with the purpose of investigating which factors could be considered of significant risk for the development of basal cell carcinoma. A total of 259 cases of basal cell carcinoma diagnosed from July 1991 to July 1992 were compared with 518 controls matched for age and sex. All subjects in both groups were white. Protocol data were submitted to statistical analysis by the chi-square test and by multiple conditional logistic regression analysis and the following conclusions were reached: 1) light skin color (types I and II of the Fitzpatrick classification), odds ratio of 2.8; outdoor work under constant sunlight, odds ratio of 5.0; the presence of actinic lesions due to exposure to the sun, odds ratio of 4.9, are risk factors per se. 2) Type III skin in the Fitzpatrick classification only represents a risk factor when the patient reports a history of intense sunburns, but not in the absence of such a history. 3) Sunburns per se do not represent a risk factor althorig the point made in item 2 of these conclusions is valid. 4) Other suspected risk factors whose significance was not confirmed by multiple conditioned logistic regression analysis were: residence in rural areas, light eyes and blond hair color, extent of the awareness of the "sun x skin cancer" relationship, familial occurrence of skin cancer, excessive exposure to the sun, and freckles appearing in childhood.

Highlights

Basal cell carcinoma (BCC) is the most common cancer occurring in human beings, but is one of the least studied types of cancer[17]
When the risk factors were analyzed by multiple conditional logistic regression, only three variables continued to be significant (Table 2)
Once it had been determined by the statistical methods applied that the risk variables were three, it was possible to construct the logarithmic equation that expressed the logistic disease model, i.e., the equation for BCC: Logistic disease model: 1,5938.x1 + 1,6041.x2+ 1,0208.x3 where x1 represents agricultural activity; it should be kept in mind that in a given patient the value of x1 will be one or zero, according to the presence or absence of this activity

Summary

Introduction

Basal cell carcinoma (BCC) is the most common cancer occurring in human beings, but is one of the least studied types of cancer[17]. In 1988, more than 400,000 cases of BCC were diagnosed in the USA32, as opposed to 980,000 cases diagnosed for all other types of cancer together. The latest survey made in Brazil by the National Tumor Registration Program**, corresponding to the years 1981 to 1985, reports 139,407 skin cancers, 99,176 of which were BCC. There seems to be an approximate annual mean of about 20,000 new recorded BCC cases for Brazil as a whole. These numbers do not give the complete picture (only the cases submitted to anatomopathological examination were computed), this occurrence is still almost twice that of cancer of the cervix, the second most frequent type of cancer in Brazil

Results

Discussion

Conclusion