The incidence of skin cancer is increasing worldwide. Protecting the skin from the sun by wearing protective clothing, using a sunscreen with appropriate sun protection factor, wearing a hat, and avoiding the sun are recommended as primary preventive activities by cancer agencies. In this paper the recent data relating to skin cancer primary preventive behaviour in Australia and other countries is reviewed. Comparison of the studies in a table format summarizing the methods, objectives, participants, findings and implications may be obtained from the corresponding author. The sun protection knowledge, attitudes and behaviour patterns observed in Australia are similar in other countries, although Australian studies generally report higher knowledge levels about skin cancer and higher levels of sun protection. The findings suggest that sunscreen is the most frequent method of sun protection used across all age groups, despite recommendations that it should be an adjunct to other forms of protection. While young children's sun protective behaviour is largely influenced by their parents' behaviours, they are still under protected, and sun protective measures such as seeking shade, avoiding the sun and protective clothing need to be emphasized. Adolescents have the lowest skin protection rates of all age groups. Within the adult age range, women and people with sensitive skin were most likely to be using skin protection. However, women were also more likely than men to sunbath deliberately and to use sun-tanning booths. The relationship between skin protection knowledge and attitudes, attitudes towards tanning and skin protection behaviour needs further investigation. Further studies need to include detailed assessments of sunscreen use and application patterns, and future health promotion activities need to focus on sun protection by wearing clothing and seeking shade to avoid increases in the sunburn rates observed to date.
The epidemiological literature concerned with predisposing factors for skin cancer emphasizes the considerable influence of ultraviolet (UV) radiation on the incidence of skin cancer (Turner, 1998). Australia has the highest rates of skin cancer in the world (Baade et al., 2000; Marks, 2000; Australian Institute of Health and Welfare, 2002; Marks, 2002). In recognition of these high rates and the number of skin cancers that could potentially be prevented, National Goals and Targets for Australia (Australian Bureau of Statistics, 1994) recommended a reduction in exposure to sunlight for all age groups, and especially for those people at high risk of skin cancer. Included in the high-risk group are people who have skin that burns and never tans, those who have a large number of acquired melanocytic naevi and freckles, those who have dysplastic naevi and those who have solar kurtosis (MacKie et al., 1989; Preston and Stern, 1992; MacKie, 1998; Marks, 2000).
Overall, primary prevention of skin cancer is concerned with a reduction in the risk factors for skin cancer, most notably sun exposure and sunburn (Borland et al., 1990; MacKie, 1998; Turner, 1998; Marks, 1999), through environmental changes, social changes and behavioural modification [National Health and Medical Research Council (NHMRC), 1996; Morris et al., 1998]. This includes such diverse activities as getting people to wear hats and long-sleeved clothes, stay in the shade, create shade by planting trees or constructing other canopies, reschedule work practices and sporting times, and other activities. Recent results from Australia suggest that the incidence of both non-melanocytic skin cancer (Staples et al., 1998) and malignant melanoma (Giles and Thursfield, 1996) may have decreased in recent years, especially in younger adults, which could be an encouraging result of public health efforts to date (Staples et al., 1998). National Goals and Targets for Australia also highlighted children and adolescents as target groups for primary preventive efforts, since prevention of damage to developing skin by UV radiation might have greatest skin cancer preventive effect. Inducing sun protective behaviour in children may additionally foster healthy sun protection practices throughout their lives (Kelly et al., 1994; NHMRC, 1996; Glanz et al., 1999; Graffunder et al., 1999; Marks, 1999). It has been estimated that 78% of accumulated lifetime sun exposure and damage can be eliminated if children use sunscreen continuously when outdoors, from infancy to 18 years (Stern et al., 1986). Adolescents were described as being reluctant to use sun protection and to have less favourable sun protection attitudes compared with children. Special programs designed to appeal to this age group to increase their sun-protective behaviour need to be developed (Lower et al., 1998a; Lower et al., 1998b; Graffunder et al., 1999).
Some controversy about the recommendation of sunscreen as primary preventive activity has been raised over the last decade. Sunscreen is effective in reducing solar keratoses (Thompson et al., 1993) and sunburn (Pruim and Green, 1999). However, several epidemiological studies suggested an increase in skin lesions among sunscreen users, possibly because people are compensating for sunscreen use by remaining in the sun for longer periods (Hunter et al., 1990; Autier et al., 1995; Westerdahl et al., 1995; Autier and Dore, 1998; Autier et al., 1998; Autier et al., 1999; Robinson et al., 2000). However, even before these results were published, sunscreen has been recommended as an adjunct to other forms of protection in Australia, and not a substitute for it (ACS, 1993; NHMRC, 1996). Sunscreen was recommended as an alternative means of protection for situations where clothing may not be desirable or appropriate (Turner, 1998; Pruim and Green, 1999). Most current guidelines on the primary prevention of skin cancer still feature the three main messages introduced in the ‘Slip! Slop! Slap!’ campaigns more than 20 years ago (Weinstock, 2000; Mortague et al., 2001). These include protective clothing, correctly applied and reapplied sunscreen, and a wide-brimmed hat. Additionally, sun exposure during midday hours should be avoided whenever possible.
It was the aim of this review to describe current patterns of sun protection for primary prevention of skin cancer in Australia and overseas, with a special emphasis on sunscreen, sunscreen application behaviour and sunscreen alternatives.
For the purpose of this review, the term ‘children’ refers to children aged between 0 and 12 years, ‘adolescents’ refers to secondary school-age children (12–18 years old) and ‘adults’ are those aged ≥18 years. Studies were included if they specified the research question, methods and sample used to obtain the reported results (Kerr et al., 1998). The Medline and Psychlit databases were searched from January 1990 to June 2003 for English-language papers including at least one of the following terms: ‘skin cancer’ or ‘skin neoplasm’ or ‘melanoma’, and at least one of the terms ‘prevention’ or ‘protection’ or ‘education’. The bibliographies of articles were also searched for additional potentially relevant studies. For inclusion in this review, studies must have focussed on the prevalence of preventive activities, not on outcomes of interventions to increase preventive activities, as reviewed elsewhere (Marks and Hill, 1992; Morris and Elwood, 1996; Buller and Borland, 1999; Carter et al., 1999; Marks, 1999). However, if an intervention study contained relevant pre-intervention baseline data, it was included.
Prevalence of sun protection in children
Sunscreen was the most frequently used sun protection method for children (Bennetts et al., 1991; Zinman et al., 1995; Olson et al., 1997; Glanz et al., 1999; Robinson et al., 2000). Protective clothing and hats were much less frequently used, however parents utilized them most frequently for children 0–3 years of age compared with children >3 years (Foot et al., 1993; Jarett et al., 1993; Dixon et al., 1999; Stanton et al., 2000). Correspondence can be observed between the reduction in the use of protective clothing for older children and an increased rate of sunburn (Foot et al., 1993; Dixon et al., 1999; Stanton et al., 2000). No consistent differences between girls and boys have been reported in the level or mode of sun protection methods used. Only a minority of early child care centres and primary schools practised sun protection measures, such as avoiding the midday sun, and had written sun protection policies (Schofield et al., 1991; Girgis et al., 1993; Schofield et al., 1993).
Children's sun protective behaviour was reported to depend on their parents' advice (Bennetts et al., 1991; Fisher et al., 1996; Stanton et al., 2000; Weinstein et al., 2001; O'Riordan et al., 2003) and most studies used parents' responses to questionnaires to establish children's sun protection. Parents' knowledge about skin cancer and skin protection was reported to be high (Grob et al., 1993; Olson et al., 1997), for example 86% of parents in the study by Dixon et al. (Dixon et al., 1999) recommended that their children wear a hat. Parents who were more knowledgable and who used sun protection for themselves were more likely to protect their children from the sun (Grob et al., 1993; Olson et al., 1997; O'Riordan et al., 2003). The influence of parents' sun protective attitudes and behaviours is notable even after children take responsibility for their own skin protection (Bennetts et al., 1991; Fisher et al., 1996). For example, a study of children and parents at the beach found that with children who were not adequately protected, corresponding low levels of protection were observed among their parents (Bennetts et al., 1991; Grob et al., 1993). Robinson et al. reported a significant association between parents' and children's sunburn and sunscreen use (Robinson et al., 2000). Parents in this study perceived a tan as healthy, especially for males and older children. Parents were observed to use some sun protective measures such as sunglasses and seeking shade more frequently for themselves than for their children (Glanz et al., 1999).
Chronologically, across studies the prevalence of sunscreen use for children seems to increase. Overall, sunscreen use emerged as the most frequently used sun protection method for children. However, particular attention to detail may be necessary when assessing this sun protective method. For example, in an American study, parents applied sunscreen to their children <1 h after families arrived at the beach (Robinson and Rademaker, 1998). No study has assessed sunscreen re-application patterns, and sunscreen application to difficult to reach areas such as the back of the legs, the ears and the neck in children.
As reported for children, sunscreen was the sun protection method most commonly used by adolescents (McGee and Williams, 1992; Grob et al., 1993; Lowe et al., 1993; Pratt and Borland, 1994; Lupton and Gaffney, 1996; Lower et al., 1998b; Smith et al., 2002). Adolescents had a high level of knowledge about skin cancer, sun protection and risk factors for melanoma (McGee and Williams, 1992; Gillespie et al., 1993; Grob et al., 1993; Lowe et al., 1993; Robinson et al., 1997b).
Typically, adolescent females were more likely than males to wear sunscreen (Banks et al., 1992; McGee and Williams, 1992; Lowe et al., 1993; Alberg et al., 2002; Geller et al., 2002), while males used hats (McGee and Williams, 1992; Robinson et al., 1997b; Alberg et al., 2002) and protective clothing (McGee and Williams, 1992) more frequently than females. Females were more likely to tan deliberately (McGee and Williams, 1992; Vail-Smith and Felts, 1993; Pratt and Borland, 1994; Wichstrom, 1994) and to use tanning booths (Wichstrom, 1994; Geller et al., 2002) compared with males. Overall, adolescent males seem more likely to protect themselves sufficiently from the sun than females (Lower et al., 1998b). Younger adolescents (age <14 years) were reported to have more positive sun protective attitudes and behaviours when compared with older adolescents (age >14 years) (Lowe et al., 1993; Pratt and Borland, 1994; Lower et al., 1998b; Horsley et al., 2002; Devos et al., 2003). However, Mermelstein et al. (Mermelstein et al., 1992) observed a higher level of sunscreen use in older adolescents. Among adolescents, the attitude towards sun protection and tanning seems to be of utmost importance, while knowledge and sun protection behaviour were not necessarily related within this age group (Broadstock et al., 1992; Fritischi et al., 1992; Kristjansson et al., 2003). Positive sun protective attitudes were observed to decrease with an increase in age (Lowe et al., 1993; Pratt and Borland, 1994; Jackson et al., 1998; Lower et al., 1998b), while positive attitude towards a tan increased (Broadstock et al., 1992; Vail-Smith and Felts, 1993; Alberg et al., 2002). Females were reported to have a more positive attitude towards a tan than males (Wichstrom, 1994). In parallel to these findings, an increase in sunburn rates in adolescents was observed with increasing age (Broadstock et al., 1992). Sunburn rates were higher among adolescents with a more positive attitude towards a tan (Davis et al., 2002), adolescents who used sunscreen at school (Horsley et al., 2002), those with sun-sensitive skin and those who spent more time outside (Hall et al., 2001; Davis et al., 2002). Overall, 66% of all adolescents reported sunburn over the last summer in an Australian study (Broadstock et al., 1992). In Queensland (Baade et al., 1996) and Victoria, 30% and 11% of all adolescents surveyed, respectively, reported that they had been sunburnt over the previous weekend (Hill et al., 1993). In a US study, >20% of all adolescents interviewed had one sunburn during the previous summer, while 27% had two or more sunburns (Alberg et al., 2002). In another US study, adolescents reported an average of 3.3 sunburns during the past year (Robinson et al., 1997b). A finding of interest for the development of intervention programs is that before their most serious sunburn, 39% of all adolescents experiencing at least one summer sunburn had applied sunscreen (Davis et al., 2002). Alberg et al. reported a decreased likelihood of sunburn if adolescents had a favourable attitude towards sun protection, whereas an increase in reported sunburn rates was associated with higher knowledge scores and sunscreen use (Alberg et al., 2002).
Some studies assessed adolescents' sunscreen use in greater detail. In a study by Lupton and Gaffney (Lupton and Gaffney, 1996), adolescents stated that they deliberately used a sunscreen with a low sun protection factor (SPF) and also delayed the application of sunscreen to get a tan. Wichstrom (Wichstrom, 1994) reported that only 50% of all adolescents in their study re-applied sunscreen and only 25% used sunscreen with an adequate SPF.
The influence of parents on adolescents' sun protective behaviour is certainly less important than on younger children, which is also reflected in fewer studies including measures of parents' sun protection behaviour in the adolescent survey questionnaires. Two studies reported a positive influence of parents' sun protective behaviour on that of adolescents (Grob et al., 1993; Fisher et al., 1996). While parents' influence becomes less important in adolescence compared with childhood, the influence of the peer group increases, and adolescents' sun protective attitudes and behaviour are significantly influenced by the opinion and perceived social norms within the peer group (Wichstrom, 1994). The influence of the school environment was highlighted by findings that a sun protection school policy, such as compulsory hat use when outside, is related to increased sun protection in adolescents, especially during school days (Fisher et al., 1996; Lower et al., 1998b; Horsley et al., 2002).
Again, as was reported for children and adolescents, sunscreen was the most commonly used measure of sun protection in adults (Foot et al., 1993; Weinstock et al., 2000). Women were more likely to use sunscreen compared with men (Pincus et al., 1991; Berwick et al., 1992; Hill et al., 1992; Hill et al., 1993; Mawn and Fleischer, 1993; Campbell and Birdsell, 1994; Hall et al., 1997; Jackson et al., 1999; Pruim et al., 1999; Schofield et al., 2001; Abroms et al., 2003; Devos et al., 2003). Sunscreen use appeared to be more common in Australia than in other countries. People who perceived themselves as at risk for skin cancer (Berwick et al., 1992) and those with sun-sensitive skin (Hall et al., 1997; Pruim et al., 1999; Weinstock et al., 2000; Schofield et al., 2001) used sunscreen more frequently than others. Higher levels of sunscreen use have also been observed in people with higher socio-economic status (Pincus et al., 1991). Compared with children and adolescents, adults used clothes or hats more frequently and in some studies this was even the most frequent sun protection method (Broadstock, 1991; Whiteman et al., 1994; Baade et al., 1996). The use of hats, protective clothing and seeking shade as measure of sun protection increased with adults' age (Berwick et al., 1992; Pruim et al., 1999).
Some studies reported detailed results on sunscreen application patterns for adults. For example, Pruim et al. (Pruim et al., 1999) reported that 76% of their sample used sunscreen at least sometimes; however, only 61% re-applied sunscreen when needed. Broadstock et al. (Broadstock et al., 1991) observed that only 24% of sunscreen users applied sunscreen before going out, while 30% applied the sunscreen some time after they left the house. Only 50% of sunscreen users were reported to apply a sunscreen with a maximum SPF (Pincus et al., 1991; Hill et al., 1992). In a Brazilian case-control study, only 3% of cases and 11% of controls applied a sunscreen with SPF >15 (Bakos et al., 2002).
Adults were reported to be aware of skin cancer, skin cancer risk factors and sun protection (Berwick et al., 1992; Mawn and Fleischer, 1993). Knowledge about the danger of sun exposure was associated with increasing sun protection in some (Cody and Lee, 1990; Hughes et al., 1993), but not all studies (Foot et al., 1993). As for the school environment, workplace policies to enable sun protective behaviour can increase such behaviour in adults (Girgis et al., 1994; Geller et al., 2001).
Compared with males, adult females were more knowledgeable about skin cancer (Hughes et al., 1993; Arthey and Clarke, 1995), believed that they have higher susceptibility, perceived fewer barriers to covering up, engaged in more protective behaviours regarding the sun and were sunburnt less often (Cody and Lee, 1990). It has been speculated that higher knowledge levels among women may be a result of them reading more magazines containing health information (Borland and Theobald, 1990; Chapman et al., 1992). However, the higher knowledge and use of sun protective measures among women conflicts with findings that women have a greater desire for a tan and their increased perception that a tan is healthy compared with men (Broadstock et al., 1992; Arthey and Clarke, 1995; Jackson et al., 1999). Jackson et al. found women with sensitive skin to be unaware of their increased risk for skin cancer and to be the group with the highest desire for a tan (Jackson et al., 1999).
Certain groups of adults experience high levels of sun exposure. Men and young people have greater exposure to the sun compared with females and older people, respectively (Broadstock, 1991; Hill et al., 1992; Hall et al., 1997; Schofield et al., 2001). Corresponding with these findings, more men than women reported being sunburnt (Schofield et al., 2001). However, younger adults and women are more likely to sunbathe deliberately (Mawn and Fleischer, 1993; Robinson et al., 1997a; Jackson et al., 1999; Devos et al., 2003) and to use tanning booths (Mawn and Fleischer, 1993; Devos et al., 2003). Several studies reported an association between sun protective behaviour and sunburn, but with inconsistent results. Baade et al. observed an increase in positive sun protection attitudes and behaviours in Queensland (Baade et al., 1996); however, they did not find any corresponding reduction in the number of sunburns. In contrast, Hill et al. reported a decreasing number of sunburns with increasing level of sun-protection knowledge and behaviour in Victorian residents (Hill et al., 1993). An increase in sunburn rates and tanning bed use has been observed in the United States in recent years (Robinson et al., 1997a).
Different recommendations on sun protection behaviour across geographical locations may be needed and further studies have been recommended (Melia et al., 2000). For example, data from a Victorian study indicates that adults' sun protective behaviour is dependent on the outside temperature (Hill et al., 1992). People seemed to be at greater risk for sunburn on mild sunny days than on cooler (<18°C) or hot days (>27°C). However, in general the patterns of sun protective behaviour are similar in Australia and the United States, and influenced more by factors such as latitude.
Sunscreen was the most frequently used method of sun protection across all age groups, despite recommendations that this form of protection should be an adjunct to other more natural forms of protection. In comparison, the use of hats, shirts, shade and other sun protection aids was less common in most (Foot et al., 1993; Lowe et al., 1993; Campell and Birdsell, 1994; Olson et al., 1997; Lower et al., 1998b; Glanz et al., 1999; Robinson et al., 2000; Stanton et al., 2000; O'Riordan et al., 2003), but not all studies (Broadstock et al., 1991; Whiteman et al., 1994; Baade et al., 1996). Very young children, older people and men were most likely to be protected by hats and clothes when outside in the sun compared with other subgroups of the population (Hill et al., 1993; Glanz et al., 1999).
Primary prevention campaigns have successfully increased the awareness of people about the potential harm of overexposure to the sun. Consistently, high knowledge levels have been reported within the studies reviewed. However, the relationship between knowledge, sun protective behaviour and the mediating effect of sun protective attitudes and attitudes towards tanning and sunbathing are still not fully understood. For example, women of all age groups were reported to have very good knowledge about skin cancer and sun protection (Banks et al., 1992; Mermelstein and Riesenberg, 1992; Hughes et al., 1993; Campbell and Birdsell, 1994; Robinson and Rademaker, 1998). At the same time, however, women frequently have a positive attitude towards a tan, sunbathe deliberately and use sun-tanning booths much more frequently than men, a behaviour pattern already present in adolescent girls (McGee and Williams, 1992; Vail-Smith and Felts, 1993; Pratt and Borland, 1994; Wichstrom, 1994; Geller et al., 2002; Devos et al., 2003). Most women used sunscreen as their favoured sun protection method (Hill et al., 1992; Campbell and Birdsell, 1994; Hall et al., 1997) and were more reluctant than men to use protective clothing or hats (Broadstock, 1991; Hill et al., 1992; Foot et al., 1993). A positive attitude towards a tan, which still exists, particularly among adolescents, women and residents of places with lower average yearly sunshine, has been shown to be associated with intentional overexposure to the sun. The complexity of effectively addressing these diverse groups within society who have a positive attitude towards tanning poses a challenge for public health researchers (Graffunder et al., 1999; Wesson and Silverberg, 2003). More studies with a multivariate design to extract confounding factors of sun protective behaviour and interactions between knowledge, attitudes and behaviours seem necessary. In recent years, researchers have started to include the distributions of risk factors and patterns of sunscreen application within subgroups of the population in their study design. These studies have revealed results with important implications for future health promotion activities (Robinson et al., 1997a; Robinson et al., 1997b; Glanz et al., 1999; Jackson et al., 1999; Stanton et al., 2000). Studies that included information on the photoaging effect of sun exposure have reported increased sun protective behaviour (Mahler et al., 2003).
Sunscreen can effectively reduce sunburn rates and the development of solar keratosis (Thompson et al., 1993; Pruim and Green, 1999), and has been recommended as a central part of sun protection since public health campaigns first started ∼20 years ago in Australia (Mortague et al., 2001), and more recently overseas (Koh and Geller, 1998; Weinstock et al., 2000). On the downside, sunscreen might reduce the feeling of getting sunburned or might lead to a false sense of protection, and by these pathways lead to an increase of exposure to harmful radiation (Jones and Leary, 1994; Robinson et al., 1997a; Autier et al., 1999). The majority of people still seem to apply sunscreen incorrectly (Robinson and Rademaker, 1998; Pruim et al., 1999). Sunscreen is applied too close to or even after considerable sun exposure (Broadstock et al., 1991; Robinson and Rademaker, 1998). People also seem to re-apply sunscreen too infrequently (Pruim et al., 1999; Devos et al., 2003) and inconsistently (Lupton and Gaffney, 1996), and seem to miss certain vulnerable parts of their body such as the ears and neck. It has been reported that people only use half the amount of sunscreen necessary to achieve the labelled sun protection factor (Neale et al., 2002). It has been suggested that some people may refrain from using sunscreen for economical reasons (Glanz et al., 1999; Tripp et al., 2003). Some studies asked for the SPF of the sunscreen used and found that a considerable proportion of people used an inadequate SPF (Pincus et al., 1991; Hill et al., 1992; Stanton et al., 2000). Measurement of the use of sunscreen alone would have missed these important findings.
Sunburn rates found within the studies reviewed are of concern. Eighty-two per cent of all 3-year-old (Stanton et al., 2000) and 3- to 5-year old (Stanton et al., 2004) Australian children have already experienced sunburn, and 66% of all adolescents reported sunburn over the previous summer in Australia (Broadstock et al., 1992). In a cross-sectional study during summer in the USA, 13.3% of all children reported having been sunburned during the past week (Robinson et al., 2000). An average rate of 3.3 sunburns within the last year was reported among US adolescents (Robinson et al., 1997b). Most primary school children seem to have positive sun protective attitudes and behaviours, which start to weaken when children enter adolescence. Several authors of studies reviewed here point to the need to develop innovative strategies to reinforce positive sun protective behaviour acquired in primary school, so that they can be successfully upheld over adolescence and transferred into adulthood, when these young adults become the role models for their own children (Mermelstein and Riesenberg, 1992; Zinman et al., 1995; Fisher et al., 1996; Olson et al., 1997; Dixon et al., 1999; Stanton et al., 2000; Alberg et al., 2002). There seems to be a paucity of such strategies to date and, consequently, an increase in sunburn rates among adults has been observed in the United States (Robinson et al., 1997a).
Most research on sun protection has been carried out in Australia or the United States. Other authors have commented that results obtained in populations constantly exposed to a high amount of solar radiation might not be applicable to other populations (Glanz et al., 1999). For example, Melia et al. (Melia et al., 2000) noted that an objective positive effect of moderate sun exposure during summer might exist. Although economical problems related to sun protection, such as the high costs associated with appropriate sunscreen use, were mentioned in several studies [e.g. (Glanz et al., 1999; Jackson et al., 1999; Robinson et al., 2000; Stanton et al., 2000)], differences in sun protection between socio-economic groups have rarely been investigated in studies to date.
A long-term, coordinated multi-level approach to increase sun protection that uses a range of strategies needs to be developed over the next few years. Messages need to be specifically targeted for at-risk groups (especially by age, gender and skin type), and approaches need to be refreshed and updated regularly, particularly to capture young markets. Specific instructions on the correct application and re-application of sunscreen seem to be urgently needed, and the common and possibly dismal behaviour of sunscreen users to stay in the sun for longer periods than recommended, and the importance of using sunscreen as an adjunct to the primary sun protective method rather than instead of it need to be included in future health promotion campaigns. Reduction of the prevalence of sunburn currently observed in children and adolescents is of great priority. A reduction in sunburn rates may be best facilitated by the increased use of protective clothing, wide-brimmed hats and seeking shade. Skin cancer needs to remain on the social agenda through a variety of mechanisms, and innovative new strategies are needed to achieve or maintain high levels of awareness and sun protective behaviour.
Findings of this review paper in the form of tables may be obtained from the corresponding author. The tables show a breakdown of articles into Australian and overseas studies, for children, adolescents and adults. The studies are compared with respect to their methods, objectives, participants, findings and implications.
1Cancer Prevention Research Centre, School of Population Health and 2School of Health and Rehabilitation Sciences, University of Queensland, Brisbane, Queensland, Australia, 3Queensland Cancer Fund, Brisbane, Queensland, Australia and 4Queensland University of Technology, Brisbane, Queensland, Australia