Jolieke C. van der Pols

Prolonged Prevention of Squamous Cell Carcinoma of the Skin by Regular Sunscreen Use

Half of all cancers in the United States are skin cancers. We have previously shown in a 4.5-year randomized controlled trial in an Australian community that squamous cell carcinomas (SCC) but not basal cell carcinomas (BCC) can be prevented by regular sunscreen application to the head, neck, hands, and forearms. Since cessation of the trial, we have followed participants for a further 8 years to evaluate possible latency of preventive effect on BCCs and SCCs. After prolonged follow-up, BCC tumor rates tended to decrease but not significantly in people formerly randomized to daily sunscreen use compared with those not applying sunscreen daily. By contrast, corresponding SCC tumor rates were significantly decreased by almost 40% during the entire follow-up period (rate ratio, 0.62; 95% confidence interval, 0.38-0.99). Regular application of sunscreen has prolonged preventive effects on SCC but with no clear benefit in reducing BCC. (Cancer Epidemiol Biomarkers Prev 2006;15(12):2546–8)

The effect of personal characteristics on the validity of nutrient intake estimates using a food-frequency questionnaire.

OBJECTIVE To assess validity of the Nambour food-frequency questionnaire (FFQ) relative to weighed food records (WFRs), and the extent to which selected demographic, anthropometric and social characteristics explain differences between the two dietary methods. DESIGN Inter-method validity study; 129-item FFQ vs. 12 days of WFR over 12 months. SETTING Community-based Nambour Skin Cancer Prevention Trial. SUBJECTS One hundred and fifteen of 168 randomly selected participants in the trial (68% acceptance rate) aged 25-75 years. RESULTS Spearman correlations between intakes from the two methods ranged from 0.18 to 0.71 for energy-adjusted values. Differences between FFQ and WFR regressed on personal characteristics were significantly associated with at least one characteristic for 16 of the 21 nutrients. Sex was significantly associated with differences for nine nutrients; body mass index (BMI), presence of any medical condition and age were each significantly associated with differences for three to six nutrients; use of dietary supplements and occupation were associated with differences for one nutrient each. There was no consistency in the direction of the significant associations. Regression models explained from 7% (riboflavin) to 27% (saturated fat) of variation in differences in intakes. CONCLUSIONS The relative validity of FFQ estimates for many nutrients is quite different for males than for females. Age, BMI, medical condition and level of intake were also associated with relative validity for some nutrients, resulting in the need to adjust intakes estimates for these in modelling diet-disease relationships. Estimates for cholesterol, beta-carotene equivalents, retinol equivalents, thiamine, riboflavin and calcium would not benefit from this.

Regular Sunscreen Use Is a Cost-Effective Approach to Skin Cancer Prevention in Subtropical Settings

In many developed countries, total costs to health systems for cutaneous basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) are among the highest of all cancers, yet the investment value of preventive measures remains unknown. Using primary data from a randomized controlled trial, we estimated the cost-effectiveness of a skin cancer prevention initiative based on regular sunscreen use. Compared with usual practice (discretionary use), the sunscreen intervention cost an additional USD 106,449 (2007) to prevent 11 BCCs, 24 SCCs, and 838 actinic keratoses among 812 residents over 5 years. These health outcomes required an annual average investment of USD 0.74 per person and saved the Australian government a total of USD 88,203 in health-care costs over the same period. Such community-based interventions promoting regular sunscreen use among Caucasians in subtropical settings can prevent skin cancer and related skin tumors in practical ways and with great cost efficiency.

Meat, fish, and ovarian cancer risk: results from 2 Australian case-control studies, a systematic review, and meta-analysis

BACKGROUND Variation in meat and fish intakes has been associated with a risk of some cancers, but evidence for ovarian cancer is limited and inconsistent. OBJECTIVE We examined the association between intakes of total meat, red meat, processed meat, poultry, and fish and ovarian cancer risk. DESIGN Data came from 2 Australian population-based case-control studies conducted 10 y apart. Analyses included a total of 2049 cases and 2191 control subjects. We obtained dietary information via a food-frequency questionnaire. We estimated multivariable-adjusted odds ratios (ORs) for each study by using logistic regression and combined results of the 2 studies by using random-effects models. We also assembled the published evidence in a systematic review and meta-analysis. RESULTS Although there was no association between total or red meat intake and ovarian cancer risk, women with the highest intake of processed meat had a significantly increased risk of ovarian cancer in the 2 case-control studies (combined OR: 1.18; 95% CI: 1.15, 1.21) and the meta-analysis [7 studies; pooled relative risk (RR): 1.20; 95% CI: 1.07, 1.34]. In contrast, a frequent intake of poultry was associated with borderline significant reductions in risk in the 2 case-control studies (combined OR: 0.83; 95% CI: 0.67, 1.03) and the meta-analysis including 7 additional studies (pooled RR: 0.90; 95% CI: 0.79, 1.01). High fish intake was associated with a significantly reduced risk in the 2 case-control studies (combined OR: 0.76; 95% CI: 0.62, 0.94) and a smaller borderline significant reduction in the meta-analysis (6 additional studies; pooled RR: 0.84; 95% CI: 0.68, 1.03). CONCLUSION Our results suggest that low consumption of processed meat and higher consumption of poultry and fish may reduce the risk of ovarian cancer.

Food intake and risk of squamous cell carcinoma of the skin in a community: the Nambour skin cancer cohort study.

There is some evidence that dietary factors may modify the risk of squamous cell carcinoma (SCC) of the skin, but the association between food intake and SCC has not been evaluated prospectively. We examined the association between food intake and SCC incidence among 1,056 randomly selected adults living in an Australian sub‐tropical community. Measurement‐error corrected estimates of intake in 15 food groups were defined from a validated food frequency questionnaire in 1992. Associations with SCC risk were assessed using Poisson and negative binomial regression to the persons affected and tumour counts, respectively, based on incident, histologically confirmed tumours occurring between 1992 and 2002. After multivariable adjustment, none of the food groups was significantly associated with SCC risk. Stratified analysis in participants with a past history of skin cancer showed a decreased risk of SCC tumours for high intakes of green leafy vegetables (RR = 0.45, 95% CI = 0.22–0.91; p for trend = 0.02) and an increased risk for high intake of unmodified dairy products (RR = 2.53, 95% CI: 1.15–5.54; p for trend = 0.03). Food intake was not associated with SCC risk in persons who had no past history of skin cancer. These findings suggest that consumption of green leafy vegetables may help prevent development of subsequent SCCs of the skin among people with previous skin cancer and that consumption of unmodified dairy products, such as whole milk, cheese and yoghurt, may increase SCC risk in susceptible persons.

Knowledge and attitudes about vitamin D and impact on sun protection practices among urban office workers in Brisbane, Australia.

Background: Sun exposure is the main source of vitamin D. Increasing scientific and media attention to the potential health benefits of sun exposure may lead to changes in sun exposure behaviors. Methods: To provide data that might help frame public health messages, we conducted an online survey among office workers in Brisbane, Australia, to determine knowledge and attitudes about vitamin D and associations of these with sun protection practices. Of the 4,709 people invited to participate, 2,867 (61%) completed the questionnaire. This analysis included 1,971 (69%) participants who indicated that they had heard about vitamin D. Results: Lack of knowledge about vitamin D was apparent. Eighteen percent of people were unaware of the bone benefits of vitamin D but 40% listed currently unconfirmed benefits. Over half of the participants indicated that more than 10 minutes in the sun was needed to attain enough vitamin D in summer, and 28% indicated more than 20 minutes in winter. This was significantly associated with increased time outdoors and decreased sunscreen use. People believing sun protection might cause vitamin D deficiency (11%) were less likely to be frequent sunscreen users (summer odds ratio, 0.63; 95% confidence interval, 0.52-0.75). Conclusions: Our findings suggest that there is some confusion about sun exposure and vitamin D, and that this may result in reduced sun-protective behavior. Impact: More information is needed about vitamin D production in the skin. In the interim, education campaigns need to specifically address the vitamin D issue to ensure that skin cancer incidence does not increase. Cancer Epidemiol Biomarkers Prev; 19(7); 1784–9. ©2010 AACR.

Clinical signs of photodamage are associated with basal cell carcinoma multiplicity and site: A 16-year longitudinal study

Although sun exposure is known to be associated with basal cell carcinoma (BCC), it is not known what determines multiple occurrences of BCCs among sporadically affected individuals or why BCCs develop on uncommonly sun‐exposed body sites like the trunk. In a prospective community‐based skin cancer study in Queensland, Australia, we studied all participants who experienced a histologically confirmed BCC from 1992 to 2007. Sun exposure history was monitored, and dermatologists documented phenotype at baseline and signs of photodamage over the study period. Anatomic sites of all incident BCCs were recorded. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using logistic regression. Of 401 participants who developed a new BCC during the 16 years of follow‐up, 232 (58%) developed more than 1. Male sex (OR = 2.5, 95% CI 1.5–5.3) and age 60 or over (OR = 4.2, 95% CI 1.5–11.8) but not skin type were associated with highest BCC counts among those affected. Participants with high numbers of solar keratoses were most likely to experience the highest BCC counts overall (OR = 4.3, 95% CI 1.4–13.5). Moreover, occurrences of BCC on the trunk (OR = 3.3, 95% CI 1.4–7.6) and on the limbs (OR = 3.7, 95% CI 2.0–7.0) were strongly associated with high numbers of solar keratoses on these sites, respectively. Among those newly affected by BCC, chronic cutaneous sun damage predicts those who will be affected by more than 1 BCC, while chronic sun damage on the trunk and limbs predicts BCC occurrence on the trunk and limbs, respectively.

Vitamin D Status and Skin Cancer Risk Independent of Time Outdoors: 11-Year Prospective Study in an Australian Community

Vitamin D may have anti-skin cancer effects, but population-based evidence is lacking. We therefore assessed associations between vitamin D status and skin cancer risk in an Australian subtropical community. We analyzed prospective skin cancer incidence for 11 years following baseline assessment of serum 25(OH)-vitamin D in 1,191 adults (average age 54 years) and used multivariable logistic regression analysis to adjust risk estimates for age, sex, detailed assessments of usual time spent outdoors, phenotypic characteristics, and other possible confounders. Participants with serum 25(OH)-vitamin D concentrations above 75 nmol  l(-1) versus those below 75 nmol  l(-1) more often developed basal cell carcinoma (odds ratio (OR)=1.51 (95% confidence interval (CI): 1.10-2.07, P=0.01) and melanoma (OR=2.71 (95% CI: 0.98-7.48, P=0.05)). Squamous cell carcinoma incidence tended to be lower in persons with serum 25(OH)-vitamin D concentrations above 75 nmol  l(-1) compared with those below 75 nmol  l(-1) (OR=0.67 (95% CI: 0.44-1.03, P=0.07)). Vitamin D status was not associated with skin cancer incidence when participants were classified as above or below 50 nmol  l(-1) 25(OH)-vitamin D. Our findings do not indicate that the carcinogenicity of high sun exposure can be counteracted by high vitamin D status. High sun exposure is to be avoided as a means to achieve high vitamin D status.

Predicting vitamin D deficiency in older Australian adults

There has been a dramatic increase in vitamin D testing in Australia in recent years, prompting calls for targeted testing. We sought to develop a model to identify people most at risk of vitamin D deficiency.

Serum vitamin D levels in office workers in a subtropical climate.

Vitamin D is necessary to maintain healthy bones, and may prevent other chronic diseases. There is limited information regarding the vitamin D status of people living in climates with relatively high ambient ultraviolet radiation. We therefore aimed to determine serum 25(OH)D levels in a group of office‐workers in subtropical Australia. We collected blood from 129 office workers in summer (n = 129) and 175 in winter (91 in both seasons). Serum 25(OH)D was estimated using a commercial chemiluminescent immunoassay and we asked participants to complete questionnaires about sun exposure and diet for the month prior to blood collection. Summer and winter mean serum 25(OH)D was 74 (95% CI 70–77) nmol L−1 and 54 (95% CI 51–57) nmol L−1, respectively. In summer, 14% of participants were classed as “insufficient,” compared with 51% in winter. High 25(OH)D levels in summer were associated with time spent outdoors in nonpeak UV periods, while in winter high levels were associated with intake of vitamin D from food or supplements. The high prevalence of vitamin D insufficiency observed in this population highlights the need for further examination of the relation between sunlight and vitamin D production to enable more accurate sun exposure recommendations.