A clinical and experimental study of basal cell carcinoma : aspects on epidemiology, genetics and microphysiology

In the present thesis we report on basal cell carcinoma from the points of view of its incidence, risk factors and pathogenesis, with special interest in patients with more than one basal cell carcinoma in life. Incidence was studied for southern Stockholm during two periods separated by two decades, 1971-1980 and 1996-1997. During the first period the annual incidence had increased by about 12 % and between the periods, sixfold. While this reflects a true increase, a part must be attributed to patients returning with new basal cell carcinomas; and another part to increased diagnostic activity. The median time to a second basal cell carcinoma, developed by 53% of our population, was 21 years. This time interval is much longer than previously published. No phenotypic marker for patients with two or more basal cell carcinomas was found among 110 consecutively collected patients who met the requirements. However skin tumour among relatives had a significant odds ratio of about 10. To investigate the indication of heredity we analysed a possible association with HLA class 11 antigen. No association was found for patients with more than four basal cell carcinomas, using high resolution genomic tissue typing. The basal cell carcinoma tumour is a malignant tumour which metastasises very seldom. At the same time it is a slow-growing tumour with good prognosis. We determined the elemental composition of BC-cells. Energy-dispersive X-ray microanalysis was used on thick-sectioned carcinomas. The elemental composition corresponds more to that of psoriasis than to that of other malignant tissues. Our results suggest that maybe basal cell carcinomas should not be classified as malignant tumours after all