Jakob Heydenreich

Weather conditions and daylight‐mediated photodynamic therapy: protoporphyrin IX‐weighted daylight doses measured in six geographical locations

Background  Photodynamic therapy (PDT) is an attractive therapy for nonmelanoma skin cancers and actinic keratoses (AKs). Daylight‐mediated methyl aminolaevulinate PDT (daylight‐PDT) is a simple and painless treatment procedure for PDT. All daylight‐PDT studies have been performed in the Nordic countries. To be able to apply these results in other parts of the world we have to compare the daily protoporphyrin IX (PpIX) light dose in other countries with the PpIX light doses found in Nordic countries.

Vitamin D Level in Summer and Winter Related to Measured UVR Exposure and Behavior

The influence of the summer UVR exposure on serum‐25‐hydroxyvitamin D (25(OH)D) in late summer and winter was investigated in an open study on 25 healthy, adult volunteers. The UVR exposure dose in standard erythema dose (SED) was monitored continuously during a summer season with personal, electronic wristwatch UVR dosimeters and sun exposure diaries. Constitutive and facultative skin pigmentation was measured in September. 25(OH)D was measured in September and February and was in mean 82 nmol/L ± 25 (mean ± SD) in September and 56 nmol/L ± 19 (mean ± SD) in February. The received cumulative UVR dose measured during a mean of 121 days was 156 SED ± 159 (mean ± SD). The following UVR exposure parameters correlated with 25(OH)D in September and February, respectively: (1) The cumulative UVR dose (r = 0.53; P < 0.01) and (r = 0.43; P = 0.03); (2) Mean daily hours with UVR measurements monitored by the dosimeter (r = 0.64, P = 0.001) and (r = 0.53; P = 0.007); (3) Days “with sun‐exposed upper body” (r = 0.58, P = 0.003) and (r = 0.50; P = 0.01); (4) Facultative pigmentation (r = 0.47; P < 0.02) and (r = 0.7; P < 0.001); (5) Constitutive pigmentation (r = 0.06, n.s.) and (r = 0.43, P = 0.03). Neither days “sunbathing” nor days with “sunscreen applied” correlated with 25(OH)D. The fall in 25(OH)D during winter was dependent on the entry value.

Skin autofluorescence as a biological UVR dosimeter.

Background/Purpose: Collagen is one of the major endogenous skin fluorophores. Alteration in the structure of collagen due to chronic ultraviolet radiation (UVR) exposure may influence the intensity of the autofluorescence. The aim of this study was to investigate the relation between collagen‐linked autofluorescence and sun exposure to clarify whether the skin can be used as a biological UVR dosimeter.

Continuous ultra-low-intensity artificial daylight is not as effective as red LED light in photodynamic therapy of multiple actinic keratoses

Daylight‐mediated photodynamic therapy (PDT) is a simple and tolerable treatment of nonmelanoma skin cancer. It is of interest which light intensity is sufficient to prevent accumulation of protoporphyrin IX (PpIX) and effectively treat actinic keratoses (AKs). We compared the efficacy of PDT with light‐emitting diode (LED) to daylight‐mediated PDT with very low‐intensity artificial daylight (‘daylight’) in the treatment of multiple AKs in the face or scalp.

Alternatives to Outdoor Daylight Illumination for Photodynamic Therapy--Use of Greenhouses and Artificial Light Sources.

Daylight-mediated photodynamic therapy (daylight PDT) is a simple and pain free treatment of actinic keratoses. Weather conditions may not always allow daylight PDT outdoors. We compared the spectrum of five different lamp candidates for indoor “daylight PDT” and investigated their ability to photobleach protoporphyrin IX (PpIX). Furthermore, we measured the amount of PpIX activating daylight available in a glass greenhouse, which can be an alternative when it is uncomfortable for patients to be outdoors. The lamps investigated were: halogen lamps (overhead and slide projector), white light-emitting diode (LED) lamp, red LED panel and lamps used for conventional PDT. Four of the five light sources were able to photobleach PpIX completely. For halogen light and the red LED lamp, 5000 lux could photobleach PpIX whereas 12,000 lux were needed for the white LED lamp. Furthermore, the greenhouse was suitable for daylight PDT since the effect of solar light is lowered only by 25%. In conclusion, we found four of the five light sources and the greenhouse usable for indoor daylight PDT. The greenhouse is beneficial when the weather outside is rainy or windy. Only insignificant ultraviolet B radiation (UVB) radiation passes through the greenhouse glass, so sun protection is not needed.

Determinants of personal ultraviolet-radiation exposure doses on a sun holiday

Background  A great number of journeys to sunny destinations are sold to the Danish population every year. We suspect that this travel considerably increases personal annual ultraviolet‐radiation (UVR) exposure doses. This is important because such exposure is the main cause of skin cancer, and studies have shown a correlation between intermittent solar UVR exposure and malignant melanoma.

A sun holiday is a sunburn holiday

Many people take holidays in sunny locations with the express aim of sunbathing. This may result in sunburn, which is a risk factor for skin cancer. We investigated 25 Danish sun seekers during a weeks holiday in the Canary Islands. The percentage of body surface area with sunburn was determined by daily skin examinations by the same observer. Erythemally effective ultraviolet radiation (UVR) exposure was assessed with time‐stamped personal dosimeters worn on the wrist. Volunteers reported their clothing cover and sunscreen use in diaries, and this information was used to determine body site‐specific UVR doses after adjustment for sun protection factor. Remarkably, we found that all volunteers sunburned at some point. The risk of sunburn correlated significantly with the adjusted body site‐specific UVR dose. Furthermore, there was also a significant relationship between the daily UVR dose and percentage of body surface area with sunburn. Our study shows that holiday UVR exposure results in a high risk of sunburn, which potentially increases the risk of skin cancer. Possible protection by melanogenesis is insufficient to protect against sunburn during a 1‐week sun holiday. Finally, our data clearly support a substantial skin cancer risk from sun holidays.

Sun behaviour after cutaneous malignant melanoma: a study based on ultraviolet radiation measurements and sun diary data.

Background  It has been reported that patients with cutaneous malignant melanoma (CMM) can lower their risk of a second primary melanoma by limiting recreational sun exposure. Previous studies based on questionnaires and objective surrogate measurements indicate that before their diagnosis, patients with CMM are exposed to higher ultraviolet radiation (UVR) doses than controls, followed by a reduction after diagnosis.

Sun behaviour and personal UVR exposure among Europeans on short term holidays

Solar ultraviolet radiation (UVR) is known to be the main cause of skin cancer, the incidence of which is rising with national differences across Europe. With this observation study we aimed to determine the impact of nationality on sun behaviour and personal UVR exposure on sun and ski holidays. 25 Danish and 20 Spanish sun-seekers were observed during a sun holiday in Spain, and 26 Danish and 27 Austrian skiers were observed during a ski holiday in Austria. The participants recorded their location and clothing in diaries. Personal time-logged UVR data were recorded as standard erythema doses (SEDs) by an electronic UVR dosimeter worn on the wrist. Danish sun-seekers were outdoors for significantly longer, received significant higher percentages of ambient UVR, and received greater accumulated UVR doses than Spanish sun-seekers. Danish skiers were also outdoors for significantly longer than Austrian skiers, but the behaviour of the Danish skiers did not result in significantly greater accumulated UVR doses. Both Danish and Spanish sun-seekers and Danish and Austrian skiers received substantial UVR doses. The behaviours influence on the UVR doses received by the Danish participants may indicate an explanation of the higher skin cancer incidence among Scandinavians compared with other European populations.

Variables in full-body ultraviolet B treatment of skin diseases

Ultraviolet B (UVB) treatment is most often performed according to a fixed schedule, not necessarily considering important variables such as UV intensity, type of UVB source and skin pigmentation. These variables can rather easily be taken into consideration by the right choice of dosing unit. The advantage of going from dosing in time to Joule to standard erythema dose or to minimal erythema dose is considered. The size of most variables may be diminished considerably. Following these guidelines, it is possible to increase the efficacy of UVB phototherapy without increasing the risk of unintentional burning.