Skin cancer is common in North America. Incidence rate trends are potentially important in the assessment of the effects of measures to increase sun awareness in the population as well as measures to reduce sun damage.
To determine the incidence of basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and cutaneous malignant melanoma (CMM) in a geographically defined Canadian population over a 40-year period.
Data were obtained from the BC Cancer Registry for the calendar years 1973, 1983, 1993, and 2003.
Age-standardized incidence rates increased significantly from 1973 to 2003 for BCC, SCC, and CMM.
The ethnic makeup of British Columbia has changed over time, and a novel method of accounting for the effect of this on skin cancer rates is presented.
The incidence rate for skin cancers continued to rise in British Columbia, but there appears to have been a decline in the incidence of CMM and BCC in the youngest cohorts.
Actinic keratosis is the most common actinic lesion in fair-skinned populations. It is accepted as an indicator of actinic skin damage and as an occasional precursor of squamous cell carcinoma. The aim of this study was to investigate, in a cohort of patients with a diagnosis of actinic keratosis, the relative risk of developing skin cancer during a follow-up period of 10 years. This registry-based cohort study compared a cohort of 2,893 individuals in south-eastern Sweden, who were diagnosed with actinic keratosis during the period 2000 to 2004, with a matched-control cohort of 14,668 individuals without actinic keratosis during the same inclusion period. The subjects were followed for 10 years to identify skin cancer development in both cohorts. Hazard ratios with 95% confidence intervals (95% CI) were used as risk measures. Individuals in the actinic keratosis cohort had a markedly higher risk for all skin cancer forms compared with the control cohort (hazard ratio (HR) 5.1, 95% CI 4.7-5.6). The relative risk was highest for developing squamous cell carcinoma (SCC) (HR 7.7, 95% CI 6.7-8.8) and somewhat lower for basal cell carcinoma (BCC) (HR 4.4, 95% CI 4.1-5.0) and malignant melanoma (MM) (HR 2.7 (2.1-3.6). Patients with a diagnosis of actinic keratosis were found to be at increased risk of developing SCC, BCC and MM in the 10 years following diagnosis of actinic keratosis. In conclusion, a diagnosis of actinic keratosis, even in the absence of documentation of other features of chronic sun exposure, is a marker of increased risk of skin cancer, which should be addressed with individually directed preventive advice.
Survival curves may be adjusted for covariates using Aalen's additive risk model. Survival curves may be compared by taking the ratio of two adjusted survival curves; the ratio is denoted the generalized relative survival rate. Adjusting both survival curves for all but one of a common set of covariates gives the partial relative survival rate, which measures the covariate-specific contribution to the generalized relative survival rate. The generalized and partial relative survival rates have interpretations similar to the traditional relative survival rates frequently used in cancer epidemiology. In fact, the traditional relative survival rate can be generalized to a regression context using the additive risk model. This population-adjusted relative survival rate is an alternative and useful method for removing confounding effects of age, cohorts, and sex. The authors use a data set of malignant melanoma patients diagnosed from 1965 to 1974 in Norway. The 25-year survival of 1967 individuals is studied.
During carrying out clinical trial on the base of Leningrad regional clinical hospital the incidence of basal cell skin cancer of the face and scalp has been studied in adults of different age groups, as well as peculiarities of clinical course of this disease in elderly and senile age. The most commonly encountered clinical form of basal cell cancer of the face and scalp in the Leningrad region was nodular-ulcerative, which was diagnosed in clinical practice in 38.3% of cases. The features of clinical course of superficial, nodular and destruida forms in people of middle, elderly and senile age are given. It is shown that the highest frequency of occurence of these clinical forms were in age of 61-70 years.
The risk of non-melanoma skin cancer in northern Europeans who indulge in sunbathing or use a UVA solarium was estimated using a mathematical model of skin cancer incidence that makes allowance for childhood, occupational and recreational sun exposure. This model demonstrates that the cumulative incidence of skin cancer in indoor workers is about 2-3% by the age of 70, yet this risk can increase 5-fold if they indulge in a two-week sunbathing vacation each summer. The use of a UVA solarium is also shown to increase the risk of skin cancer. Because risk increases with the approximate square of annual solarium exposure, it is not possible to define a 'safe' level of exposure. Instead, it is shown that weekly use of a UVA solarium from age 20 until middle age (40-50) gives a relative cumulative incidence of 1.3 compared with non-users of sun beds and sun canopies. The risk begins to increase rapidly for more frequent use, particularly when solaria are used in combination with sunbathing.
The presence of acquired benign nevi is a risk factor for cutaneous melanoma, yet relatively little is known about the etiology of nevi. We have conducted a study of the prevalence of melanocytic nevi among 1146 white Vancouver (Canada) schoolchildren aged 6 to 18 years. Numbers of nevi per square meter of body surface area increase with age in children of both sexes. Male adolescents have more nevi than female adolescents on the head and neck as well as on the trunk, while prevalence in females is higher on the upper and lower limbs. This distribution parallels that of cutaneous melanoma in British Columbia adults. Nevi are more common in children on intermittently exposed body sites than on constantly or minimally sun-exposed sites. This suggests that exposure to strong intermittent sunlight in childhood (a risk factor for cutaneous melanoma) may also be important in the etiology of acquired benign nevi.