Test of Developed Interventions to Prevent Skin Cancer: a Randomized Study Targeting Danes Going on Vacation to Sunny Destinations With High UV Index
Phase: NA
Conditions: Sunburn, Ultraviolet Radiation Exposure, Skin Cancer, Malignant Melanoma, Non-melanoma Skin Cancer, Keratinocyte Skin Cancer
Sponsor: Brian Køster

Test of developed interventions to prevent skin cancer: a randomized study 
targeting Danes going on vacation to sunny destinations with high UV index 
 
Date: July 21, 2018 
 
Protocol ID: RCT429-2015-294 
 
 
 

Test of developed interventions to prevent skin cancer: a randomized study 
targeting Danes going on vacation to sunny destinations with high UV index 
 
 
Aim 
The aim of the study is to test a series of developed effective interventions targeting Danes 
going on vacation to sunny destinations to decrease sunburn by increasing use of shade, hats, 
protective clothing, and sunscreen to prevent skin cancer in the Danish population. 
 
Prevalence of skin cancer and sun exposure 
Incidence of malignant and non-malignant skin cancer have increased for decades in large 
parts of the world and especially in Caucasian populations [1]. In Denmark, almost 4.000 
individuals are diagnosed with a skin cancer annually (basal cell cancer not included) and 
more than 300 die from a skin cancer [2]. Exposure to ultraviolet radiation (UVR) from the 
sun and from artificial sources e.g. sunbeds is the main risk factor for skin cancer [3]. Sunburn 
is both a measure of the dose of UVR exposure received as well as an independent risk factor 
for skin cancer [4]. It has been estimated that up to 90 % of all skin cancers could be avoided 
by behavioral changes [5, 6]. One of the main sources of UVR exposure in the Danish 
population is vacations to destinations with high UV index (UVI) [7-11].  
 
The Danish sun safety campaign  
In 2007, the Danish Sun Safety Campaign was launched in a partnership between the Danish 
Cancer Society and the Danish foundation, TrygFonden. The purpose of the campaign is to 
prevent skin cancer in Denmark by increasing the use of appropriate sun protection in the 
natural sun and avoiding sunbed use in the Danish population. This study is going to be part 
of the Danish Sun Safety Campaign. Thus, experience from the campaign will be 
implemented in the study and study results will be used in the campaign afterwards. 
 
The Danish Sun Safety Campaign’s sun advice to prevent exposure to UVR from the natural 
sun are structured in three prioritized messages:  
  
Shade is the primary message, which embraces not only staying in the shade, but also staying 
out of the sun when the UVI reaches daily maximum (between 12 and 3 pm). The secondary 
message is hat and ‘shade for the body’ meaning clothes. The tertiary message is sunscreen. 
The messages should be applied in combination to be effective.  
 
The priority of the messages are in accordance with the European code against cancers 
suggestions for individual’s protection against UVR. Avoidance of UVR by staying indoor in 
the middle of the day when UVR levels are highest obviously provides the best protection. 
Shade structures provide low protection against UVR (SPF = 2-5), due to reflection and 
diffuse UVR [12]. Textiles, like clothing and hats provides high protection of the covered 
areas (SPF > 50)[13], while hats only provide low protection on shaded areas, like the face 
(SPF 2-4)[14]. Sunscreens are produced with a theoretical SPF up to 50 in Denmark (requires 
distribution of 2 mg/ml) which is categorized as high. Consumers only apply approximately 
0.5-1.0 mg/ml sunscreen, which means that the actual protection of sunscreens labeled with 
SPF 16 and SPF 36 drops below SPF 4 and SPF 6, respectively, which corresponds to low 
protection [15].   
 

The campaign has achieved substantial successful results: 
 The fraction of sunburn in the population in the Danish summer decreased from 44 % 
in 2008 to 22 % in 2014 [16] 
 Use of sunbed decreased from 26 % in 2007 to 9 % in 2014 [17] 
 
However: 
 The fraction of sunburn in the population going on vacations to sunny destinations 
with high UVI was largely unchanged from 25 % in 2008 to 27 % in 2014 [18] 
 
Vacations to sunny destinations is the most important arena for melanoma intervention  
Results from the large Norwegian Women’s Cohort (NOWAC) with 100.000+ women 
showed an OR of 1.7 (1.2-2.5) for MM when comparing one or more annual vacations to 
sunny destinations with less than one annual vacation. Each year, almost 50 % of the Danish 
population is going on a vacation to a sunny destination. Studies have shown [19, 20] that 
Danes going on vacation to destinations with high UVI receive 43 % of the annual UVR dose 
in just one week and found that all participants in the studies were sunburned (determined by 
objective measurement). Sunburn is generally underestimated by self-evaluation [21]. More 
than 90 % of the Danish population have skin type’s I-III. This means that the minimal 
erythemal dose (MED) will be exceeded by the vast majority of vacationers after only 20 
minutes or less at UV 9 (e.g. in France and Italy) or 15 min or less at UV 11 (e.g. in Thailand 
and the Canary Islands) if not protected, which results in sunburn and increased risk of skin 
cancer. Vacations to sunny destinations generally is a skin cancer risk factor, especially for 
people of Caucasian origin [22, 23]. 
 
Challenges with implementation and adherence to the sun advice 
When Danes are travelling to sunny destinations, they bring their sun-related behavior from 
the north, which is not adapted to the high UVI of the destination. For instance, the Danes do 
not take a siesta, a break from the sun, like several local populations. During 11am-3pm, 
when UVI is highest, 90 % of Danes on vacation are outside more than an hour, 72 % more 
than 2 hours and 41 % are outside more than 3 hours[24]. This is problematic as the dose and 
intensity of the radiation during prolonged times outdoors during vacations, especially to 
locations at lower latitudes, increases risk of sunburns. In addition, Danes do not have a 
strong tradition of wearing hats. The hat advice has the lowest penetration in the population. 
About 80 % of the Danes never wore a hat during their vacation and only 10 % used it often 
or always [24]. This is very unfortunate because more than 75 % of non-melanoma skin 
cancers arise in the head, neck and scalp region [25]. Sunscreen is the sun protection advice 
with the highest penetration in the population. Sunscreen has reduces squamous cell skin 
cancer and melanoma under high UVR conditions in Australia [26, 27]; however the evidence 
for the protective effects of sunscreen against sunburn and melanoma is ambiguous [28]. 
Sunscreen with sun protection factor (SPF) 15 only lets 1/15 corresponding to ~ 7% of the 
UV radiation through. However, in real life there are many pitfalls when using sunscreen that 
can reduce its effectiveness, e.g. application of insufficient amount, lack of re-application, 
missing spots, use of insufficiently low SPF, application after going outdoors in the sun, as 
well as behaviors reversing the protective effect of sunscreen such as increased duration of 
sun exposure with sunscreen and use of sunscreen for intentional tanning [10, 15, 29, 30]. 
Studies have shown that the average sunscreen application of the Danes is less than 50 % of 
the recommended amount [15, 31]. In addition, more than 50 % of the Danes applying 

sunscreen used a sunscreen with insufficient sun protection factor (SPF < 30) on their 
vacation and only 25 % re-applied sunscreen sufficiently.   
 
Therefore, there is a need to test and develop effective interventions that can improve these 
sun protection practices and reduce UVR exposure of Danes going on vacation to sunny 
destinations with a high UVI to prevent skin cancers in Denmark. 
 
Intervention study 
 
To achieve the aim of this study we will conduct a randomized controlled trial with three arms 
during May-Dec 2017. Participants will be Danish adults traveling on vacation in 2018 for a 
period of 1-3 weeks, recruited from the civil registration system. After enrollment and 
pretesting, participants will be randomly assigned to one of three experimental conditions. 
Three experimental groups will receive innovative intervention strategies for promoting sun 
protection practices during vacation – Protection Routine (1), Protection Routine (2) or both 
Protection Routine (1+2). The fourth experimental condition will be a minimal treatment 
control group. The primary outcomes of the trial will be a reduction in frequency of sunburn 
by adherence to the current sun protection advice from the Danish Cancer Society, i.e., use of 
shade, hats, protective clothing, and sunscreen as secondary outcomes. We hypothesize that 
the following two interventions will be able to reduce significantly the UVR exposure and 
risk of sunburns in Danes going on vacation to destinations with high UVI. 
 
Protection routine 1  
 
The existing evidence of sun protection against the detrimental effect of UV radiation shows 
that it is effective if performed correctly [26, 28]. We will develop a package of existing 
training and information and test if it will lead to better adherence. The package will include: 
 The rationale of the prioritized sun advice [32] 
 Activity planner, with suggestions to why a break from the sun is beneficial and how 
to plan activities before and after UVI maximum i.e. morning/early noon and 
afternoon/evening [32] 
 Download of the UV-application ‘UVindeks’ for smartphones developed by the 
campaign and activating UV alert of geographic destination [33] 
 A skin type guide 
 
The preferred type of protection of the individual varies so the information and training 
package in this arm is intended to increase the overall protection level of the individual by 
advocating several sun protection practices. The sun advice is the most basal sun protection 
communication [32]. Moving outdoor activities away from UV peak hours will theoretical 
decrease the total UVR received, while maintaining constant outdoor activity level [32]. The 
smartphone application contains information on maximum UVI and cloud cover corrected 
UVI of any desired location in the world. The cloud cover corrected prognosis makes the 
information relevant to the recipient as oppose to the standard UVI-max prognosis provided 
by national weathercasts as these only change slightly through the season [34]. Using this 
intervention will provide participants with relevant information about sun protection at the 
right time in various geographic locations. In addition, a new alert to implement higher use of 
the sun advice ‘Shade’ is integrated in the application. The application also includes a skin 

type test enabling specific messages about outdoor time before individual MED level is 
reached resulting in sunburn. This means users will receive an alert in the morning, if 
protection is needed, adapted to the location and UVR exposure to plan their time outdoors 
and avoid midday exposure. Dissemination of the UV Index alone has not shown to change 
peoples behavior [34]; however, it has been able to increase awareness [35], which is a 
precursor to changed behavior in behavioral models [36]. Additionally, sun safety smartphone 
applications have shown indications of improvement in sun protection practices in a 
randomized trial [37]. The skin type guide will also be provided as a paper version for 
individuals not using the smartphone application. Knowing your skin type is important. 
Several studies have shown that people overestimate their skin’s thresholds for UVR exposure 
leading to sunburn [38]. This multi-facetted approach adapted to the individual should be able 
to show a behavioral improvement in sun exposure and protection. 
 
Protection routine 2 
Two of the largest pitfalls in Danes sun protection is 1) not covering the most skin cancer 
prone site on the body with a hat and 2) replacing clothing with insufficient amounts of 
sunscreen. 
 A specially designed hat to wear in the sun to test the use of hat when it is available 
[39] 
 A newly developed instruction for correct application of sunscreen [40] 
Denmark is not a hat-wearing society. By making smart design hats available and attractive 
may increase this sun protection behavior, which has large potential in prevention of skin 
cancer (ibid: p2). A very simple study showed that a brief instruction to sunscreen application 
increased the provided protection significantly [40]. 
 
Protection routine 1+2 
The group will receive both above mentioned interventions and will reveal potential dose 
response effects from level of protection. 
 
Control group 
All groups including the control group will receive a minimal intervention with the current 
sun advice from the Danish Sun Safety Campaign.  
 
Study population 
The participants of the study are recruited from the Danish civil registration based system. 
The study population will represent all groups of the Danish population. Eligibility criteria for 
the project are persons living in Denmark going on vacation in May-December 2018 and 
having a smartphone compatible with either apple iOS (version 7.0 or newer) or Google 
Android (version 4.0 or newer). The period May to December is chosen as it includes all 
types of vacationers. The summer vacation constitutes the majority of the sunny vacations of 
the Danes. The period includes both the summer, where Danes typically travel to the 
Mediterranean area and the winter period where travel patterns change a bit to more exotic 
areas like Thailand, Egypt and the Canarias Islands. Exclusion criteria are persons younger 
than 18 years of age.  
 
 
 

Randomization 
The participants will be randomized to one of the intervention groups or to the minimal-
treatment control group. The randomization procedure is described in the protocol. 
 
Confounders 
Possible confounders includes age, gender, education, skin type, skin cancer history, nevi, 
sun-seeking behavior and number of sunny vacations in past 5 years [28]. 
 
Statistical methods and power calculations 
The number of completing participants (n= 1.980) is based on a power calculation, 
recruitment for similar studies conducted by the applicant [41, 42] and our recent pilot study 
(unpublished, summarized in the end of this application).  
A statistical power calculation shows that this sample size yields 95 % probability to detect a 
10-percentage point drop from 50 % to 40 % in sunburn between an intervention group and 
the control group, and 80 % probability to detect a 7-percentage point drop from 50 % to 43 
%. Our pilot study showed a 17-percentage point difference between our participants (32 %) 
relative to our annual sun surveys (49%). The number of invited participants to reach a final 
sample of ~2000 are included in the flow diagram in the protocol.  
To obtain the final study sample size, we assumed 25 % of Danes invited to participate will 
volunteer for the project [41], >80 % will use of interventions (unpublished pilot study) and > 
90 % will complete questionnaire [41, 42]. Loss to follow up after one year is expected to be 
25 % according to travel patterns with high continuity of the Danes. 
 
Multiple logistic regression analysis will be applied for analysis of differences in sunburn 
fraction. Analysis of variance will be used to analyze differences in sun protection score and 
UVR exposure score. Alpha criterion will be p=0.05 (two-tailed).  
 
Intention-to-treat analysis will be applied by using multiple imputation by chained equations 
to account for missing information on sunburn among non-responders, using PROC MI in 
SAS 9.3. The imputation procedure includes variables hypothesized to potentially predict 
missing information (age, sex, education, skin type, sun behaviour, sun protection, sun 
intentions and intervention group). Analyses will be repeated including responders only and 
counting non-responders with same sunburn fraction as responders in the control group. 
 
Clustering within families is not included in the planned analysis as it is unlikely to influence 
the results because participants from the same family have very low odds of being drawn with 
a total of 30.000 drawn out of the entire Danish population 18+ (app. 4.3 million). 
 
Evaluation by validated questionnaire 
Sun protective behavior, exposure to UVR and sunburn will be evaluated by use of a 
questionnaire validated by personal electronic UV-measurements [7, 43, 44]. This newly 
developed survey tool has made it possible in this project to evaluate the skin cancer 
interventions, without tracking of development of skin cancer which can take several years to 
develop after excessive UVR exposure. The short time period from intervention to evaluation 
minimizes recall bias. 
 
 
 

Success criteria 
The primary success criteria of the effectiveness of the interventions is a 10 % decrease in 
sunburn fraction in the intervention groups as compared to the control group in the post-
intervention measurement, as shown possible in the pilot study.  
Furthermore, we aim to reach completion and response rates of no less than 90 % of the total 
sample, which we previously showed to be possible. 
 
Secondary success criteria are increased awareness on the risk of skin cancer, increased use of 
protection (shade, clothes, hat and sunscreen) and decreased outdoor exposure when the UVI 
is highest between 12 and 3 pm. For all secondary success criteria, we aim for an 
improvement of 10 % between interventions and control group. 
 
Potential bias 
The randomization procedure ensures that all groups are similar; however, there is a risk of 
bias. The study population could be more or less likely to consist of sun seekers compared to 
the background population. This will not influence results of the trial because they should be 
equally distributed across the study arms. However, it could limit generalizability and 
influence future implementation of the interventions. The validated questionnaire allows us 
able to adjust for the received UV exposure of the participants in responder analyses.  
 
Scientific and society perspectives and relevance 
If the developed interventions are effective, they will be used in the Danish Sun Safety 
Campaign targeting Danes going on vacation to destinations with high UVI and thereby 
reduce the UVR exposure on a population level and eventually prevent skin cancers in 
Denmark. In addition, reductions in UVR exposure of the Danes will decrease the economic 
costs of skin cancer. The costs of skin cancer in Denmark were 250 million DKr annually 
during 2004-2008 [45]. While the return on investment (ROI) has not been estimated for 
Denmark, in Australia, the ROI for a campaign to prevent skin cancer was estimated to be 230 
% [46]. 
 
Product and dissemination  
The project will produce at least two scientific papers to document the effect of the study: 
‘A randomized trial of Sun Safety Behavioral Interventions among Danes going to Sunny 
Destinations: Description and Baseline-study’ 
‘Sun Safety Behavioral Interventions among Danes going to Sunny Destinations: A 
Randomized Trial ‘ 
 
In addition, we have planned participation in the 17th World Congress on Cancers of the skin 
and 4th International Conference on UV and Skin Cancer Prevention. The Danish Sun Safety 
Campaign has solid experience in disseminating results to the national press and has a person 
dedicated to the job. 
 
Expected influence on future research in skin cancer prevention 
The efficacy of sun protection methods is central to skin cancer research. It is estimated that 
up to 90 % of skin cancers could be prevented by a reduction in UVR exposure [5]. However, 
the evidence of current prevention methods to reduce UVR exposure in practice is 
insufficient. Thus, it is of utmost importance to establish evidence of current sun protection 

methods and to develop new methods to improve them where current methods are inadequate. 
The use of smartphone health applications is widespread and has great potential. However, 
such health applications, along with personal dosimeters are still poorly documented in the 
scientific literature. Providing evidence for the use of current and new sun protection methods 
is leading research worldwide, and there is a large unexploited potential in using smartphones 
and dosimeters in interventions.  
 
Organization 
The Danish Sun Safety Campaign is organized in two units, an evaluation unit and a 
campaign unit. The campaign and the individual members of the campaign has broad 
experience in setting up interventions [42, 47, 48] as well as evaluation [9, 16-18, 49] and 
scientific publication [10, 11, 29, 41, 42, 45, 47, 48, 50-60] of results is firmly implemented in 
the campaign work procedure.  
 
The applicant, Brian Køster, is already a central person in the area and has worked in skin 
cancer prevention since 2007 to secure and support the scientific evidence [10, 11, 29, 52-54] 
and during 2012-15 as a Ph.D. student to develop improved evaluation to enhance effective 
campaign efforts [41, 42, 51, 61]. The project steering group also includes  
Peter Dalum (Intervention Specialist and Head of the Danish Sun Safety Campaign), Anja 
Olsen (Senior Scientist, Epidemiologist) and David Buller (Sun Safety Intervention 
Researcher and Senior Scientist and Director of Research at Klein Buendel, Inc.).  
The applicant has conducted similar trials during his Ph.D. in the target group and has 
positive experiences concerning recruitment, consistency, validation and resources to secure 
high completion.  
 
 
National and international network 
In the field of skin cancer prevention behavior research Denmark is a leading country together 
with Australia. Centre for Research Excellence in sun and Health at Queensland University 
(CRESH) and the Australian SunSmart Campaign are important collaborators [62, 63]. 
Australian sun behavior is culturally very different from the behavior among northern 
Europeans. Key players in Denmark, and worldwide are the UVR research 
group headed by Dr. Wulff at Bispebjerg Hospital and the Danish Sun Safety Campaign. This 
project is developing further the clinical research from Dr. Wulff’ group [64-67], the 
population-based research on sun protection in warm-weather resorts [68, 69] and the use of 
smartphone technology for promoting sun protection [37, 70, 71] by Dr. Buller’s group  and 
the population based intervention efforts of the Danish Sun Safety campaign [8, 10, 29, 72].  
 
Summary of completed pilot studies securing base assumptions 
We have previously conducted feasibility and intervention studies demonstrating the 
feasibility of this study. We have shown a recruitment rate of 25 % when sampled from the 
Danish civil registration system [41]. We have also shown that the completion rate in this 
sample among the recruited participants were above 90 % [41, 42].  
 
We have now piloted the preliminary planned interventions in a small study of 147 persons 
aged 15-65 representing the Danish population in gender,  age, education and geography, 
going on vacation to a country with a higher uv-index (UVI 8+) than Denmark in the summer 
of 2016 (not published). They were recruited from a web panel during July 2016 and were 
vacationing for 1-2 weeks in July-mid August. The participants were introduced to the 

majority of the elements in intervention 1. The feasibility of intervention 2 was previously 
shown [42, 61]. Ninety-three percent received and read the material. At posttest, we showed a 
sunburn rate in the study population, which was 17 percentage points lower than reported for 
our annual survey of the Danish population. All intervention elements (Sun advice, 
smartphone application, sunscreen application guide, skin type guide) proposed in this study 
were considered relevant and useful by more than 80 % of those who completed the pilot 
study. The skin type guide scored lowest with 81 % and the app scored highest with 95 % 
among those who had it available (google android and apple ios phones; not available for 
windows phones for instance). Furthermore, we saw a 9-percentage point increase in use of 
sunscreen, while use of long-sleeves and hat was largely unchanged. The hats proposed for 
the study, were not tested in the pilot, however the feasibility of the hat was previously tested 
in minor interventions. We also show a slight increase in knowledge of the UV Index in the 
population survey from 89 % to 93 % in the pilot test. 
 
Potential pitfalls 
Albeit highly unlikely, we have sketched various scenarios that could influence the project. 
 
The project is based in the Danish Cancer Society, which means that during the project 
period, should any of the applicants change job, be long term absent/sick or likewise, 
qualified researchers of same level will replace them. 
 
The project involves products from third part companies, which can be prone to internal or 
external structural changes or bankruptcy, leaving them no possibility to deliver a given 
product. In any case, an equally qualified product will be sought in replacement. 
 
The recruitment method is register based. Should the Danish Civil Registry for some reason 
not be able to deliver data, like sudden legal changes in person data handling or likewise, 
other methods of recruitment are available. 
 
All potential changes to the project will of course be reported to funder immediately. 
 
 
 

Protocol 
Time Schedule 
 
 
 
 
Mar-Apr 2018  
Planning of 
intervention & 
evaluation 
Registering trial 
 
Ordering sample from civil registry 
system 
 
Preparation of interventions 
 
Preparation of information and 
homepage 
 
Apr-May 2018  
Recruitment and 
scheduling;  
Sending invitations 
 
 
Ordering products for intervention 
 
Baseline Questionnaire 
 
May-Dec 2018  
Execution of 
interventions 
Adjusting intervention groups according 
to participation 
 
Sending intervention packages for 
participants 
 
Sending questionnaires for post 
evaluation 
Jun 2017 -Feb 2019 
 
 
Jun - Nov 2019 (follow-
up) 
Data collection and 
data handling 
Evaluation of participation and possible 
reminders  
 
Conversion of questionnaire data files 
for SAS and Purification of data 
 
Recording of relevant UV Indexes from 
vacation destinations 
May-Dec 2019 
1-year Follow-up 
Recruitment and scheduling  
 
Sending questionnaires for evaluation 
May-Aug 2019  
Evaluation and 
documentation 
Analysis and manuscript 1 (baseline) 
Aug-Nov 2019 
Analysis and manuscript 2 (main study) 
Dec 2019 - Mar 2020 
Analysis and manuscript 3 (follow-up) 
Aug 2019 - Sep 2020  
Dissemination of 
results and 
implementation of 
successful 
interventions 
Publications in national press and 
international scientific papers 
 
Update of guidelines 
 

 
Registering trial 
The trial will be registered at clinicaltrials.gov. 
 
Civil registry sample 
The sample description of the trial to Danish health data board will be developed. Permissions 
will be gathered from The Danish Data Protection Agency and the National Committee of 
Health Research Ethics. A sample of 25.400 individuals aged 18 and older will be requested.  
 
Study population recruitment 
The study population will be recruited from the Danish Civil Registry System. The aim is to 
obtain a sample representing all groups of the Danish population. Recruitment for this type of 
trial is difficult as the target population is not easy to reach without selection bias. To improve 
recruitment rates invitations will be targeted to the person in the sample or to any family 
member in the household aged 18 and above. We aim to receive full data for a final 
population of approximately 2.000 persons. 
 
It may appear, as 8 % of the original draw in the final data is not much; however, as less than 
half of the Danes are having vacation abroad every year it corresponds to a reach of 18 % 
among those eligible for the study. Alternative recruitment approaches like airport recruiting 
most likely would not decrease any bias or yield a higher percentage of recruited travelers. In 
addition, Danes also departure from nearby airports in Germany and Sweden, which would be 
difficult to include in the project. 
 
Planned evaluation 
The evaluation will be conducted in the online survey system, SurveyXact, provided by 
Rambøll. The system is used in numerous evaluations of the Danish Cancer Society. The 
evaluation is based on the validated UV behavior questionnaire recently developed by Danish 
Sun Safety Campaign. The questionnaire will be adapted to the trial. 
 
Preparation of interventions 
An intensive intervention package was developed prior to the study. The package is composed 
by known elements from the Danish Sun Safety campaign. The package also includes 
download of the UV-App developed by the Danish Sun Safety Campaign. The app includes 
an alert function for high UV-Indexes and can be adapted to the correct location by GPS or a 
selected city around the world. This mobile app is fully developed and available for this trial. 
The participants randomized to the package will receive alerts to take precautions against 
solar UVR before and during their vacation. 
 
Invitations 
The invitations for the project will be handled (printed, enveloped and sent) by trained 
volunteers from the Danish Cancer Society. Participants will sign up for the project on a 
developed web-page of the project. On the project homepage the participants will fill in a 
short form of contact information, demographic information, departure and arrival dates of 
their upcoming vacation and baseline sun behavior information for non-responder analyses. 
Participants who have not yet planned their vacation are instructed to contact the project team  
 
 
 

Flow Diagram  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Invitations to random sample of 
Danes aged 15 years and 
above from the Civil 
Registration System, n=25.400 
Persons not eligible, 
not going abroad, 
n=14.200
Completion rate including questionnaire among participants aims to be >= 80 
% (based on rates from similar Ph.D. project (89-93 %) ) 
Intervention groups 
n=2.043, 3*681 
 
Control group, 
n= 681 
Available participants 
randomized to intervention 
or control, n=2.724 
Agree to participate, n=2.800, 25 % 
Complete baseline questionnaire 
Enrollment 
Invitations to persons eligible, 
going on vacation, n=11.200 
Unavailable in 
study period/ 
withdrawal of 
participation n= 76 
 
Protection 
routine 1+2 
n=625 
 
Protection 
routine 1 
n=625 
  
Control 
(n=625) 
Randomized 
Provisional sample,      
n=2.500 
Provisional completed sample, 
n=2.000 
Completed post-test 
Drop out from 
intervention and control 
groups, n = 224 
Total non-responders 
from completed 
intervention and control 
groups, n = 500 
Total randomized non-
responders, n = 724 
 
Protection 
routine 2 
n=625 
   

 
once they have planned it. Likewise they will be reminded every 2-3 weeks during the period 
by mail or phone. Repeated invitations will be sent after two and four weeks to non-
responders. Afterwards, participants will be contacted by the volunteers by phone to confirm 
their participation and receive information about the study. A student will be dedicated in 
organizing workflow of the volunteers and participate in the training of the volunteers. We 
have good experiences with this procedure from other projects like www.mituv.dk and 
www.statusd.dk also funded by TrygFonden. 
 
Invitations will be identical for all invited potential participants. It will include invitation to 
participate in a project about how the Danish Cancer Society can improve their knowledge 
about sun protection information and that they will be allocated to use a specific sun 
protection during their vacation. It will also include information about which procedures may 
be applied.  
 
Recruitment 
The invited participants will provide their contact data and supplemental background data 
upon recruitment on the project homepage. Only one person from a family will be enrolled in 
the study. 
 
Development of protection routines and training package intervention  
The final information package is composed by various elements from the Danish Sun Safety 
campaign as described in the project description. The package was created by an experienced 
group from the Danish Sun Safety Campaign, including experts in public health, anthropology 
and communication and was be piloted before the trial.  
 
 
Main study 
The participants will be randomized to one of the three groups below after agreeing to 
participate. The detailed distribution of participants are shown in the flow diagram. The 
randomization will be stratified by gender (Male/Female), age group (18-25, 26-35, 36-45, 
46-55, 56-65 and 65+) and region (Capital, Zealand, Northern Jutland, Central Jutland and 
Southern Denmark). The randomization procedure will be blind to the researcher. All 
participants will be contacted immediately before their vacation and will receive their 
intervention package before departure.  
 
Control group – Minimal intervention 
All groups including the control group will receive a minimal intervention with the sun advice 
from the Danish Sun Safety Campaign.  
 
Protection Routine 1 – Intensive information and training in current sun advice 
The intensive information package is described in the project description. The newly 
developed information folder, includes the sun advice of the Danish Sun Safety Campaign, 
the rationale behind the prioritization and an overview of preventive measures against the sun. 
The activity planner includes examples of outdoor activities like bathing, sports and 
excursions before and after noon (UVI maximum) and indoor activities like shopping, lunch, 
relaxation and transportation in the middle of the day and possibility to plan days in the 
vacation to minimize risk. The instructions for download of the UV-App includes use of the 
alert, and information about the features of the app; e.g. how to be informed of current UV 
risk before and during vacation. In addition, link for download of the app will be sent by both 

text-message and e-mail. The skin type guide is included in the app and comes as an 
individual entity. It includes scoring questions about tan and burn reaction in the sun, a color 
scale, eye and hair color and freckles. Afterwards the participants get a description of their 
skin type and examples of how short time their particular skin type will resist the sun before 
erythema occurs at particular UV-levels and functions as an eye-opener. The participants will 
receive a physical copy of the material by mail and an electronic version by e-mail to be able 
to revisit it.  
 
Protection Routine 2 – Thorough sunscreen and availability of hat 
The sunscreen application instruction is based on a recently developed thorough application 
instructions for use of sunscreen to counter the described problems and deficits of current 
sunscreen use. It describes every part of the body, the needed volume for that part and 
application patterns. The package will also include a hat specifically designed for protection 
and comfort and the availability of a hat will function to increase the use of hat. The hat is 
simple bucket hat version with a brim, cheap, in light fabric and foldable for easy packing. 
 
Protection Routine 1 & 2 – Combined 
As described above 
 
Completion of intervention 
While it is hoped that all individuals will use the interventions, research by our team and 
others have found that exposure to interventions typically vary across participants. Exposure 
to the interventions will be measured by post-test questionnaire. Also, use of the mobile app 
will be assessed by registering when downloaded from a link sent by email and text-message 
reminders to the participants.  Automated email and text-message reminders will be 
considered as tools to increase use of the mobile app and the personal dosimeter. Completion 
of the full intervention will be defined as follows: control group - having received the minimal 
intervention materials; Protection Routine 1- use of 50 % or more of the intervention 
materials in the package; Protection Routine 2 – . However, we will also analyze the amount 
of use of the interventions for the impact of intervention exposure on intervention 
effectiveness. 
 
 
Data collection and handling 
Data collection is executed by an electronic questionnaire sent immediately after return from 
the vacation. If unanswered reminders are sent after 4 days, 9 days and 14 days. The data 
collection methods follows results of a recent validation study, which showed that validity of 
the questionnaire answers is crucially dependent on short time from exposure to answering the 
questionnaire. Responses within 2 weeks of return from vacation were valid. 
 
 
1-year-follow-up 
Participants that have completed the intervention are invited to a follow up study the 
following year. The procedure is similar to the initial procedure. Only now, participants are 
invited by e-mail (supported by phone) and screened for possible vacation to a sunny 
destination. Participants going on a sunny vacation will receive a questionnaire immediately 
after return from the vacation for evaluation of long-term effects. 
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