Use of Sunscreen and Melanoma - Case Study Example

Introduction This paper is based on a thorough analysis of ten different research articles written on the use of sunscreens and how it can or can not endanger human skin. The fact that sunscreens help prevent sunburns or erythema led people to believe that they will also help prevent melanoma but the opposite seemed to be true. The controversy of whether sunscreen increases the risk of malignant melanoma (which is one of the deadliest forms of skin cancers) among humans has been going around since the 1990s. Many researchers have been conducted in this regard and the results have more or less proven otherwise. However, it can be seen through the analysis of these studies that those researchers which led to the controversy did not take proper control of various external variables such as the other lotions or creams used by the target audience, the sensitivity of their skin or any other skin diseases that they have or had in the past which led to the sue of sunscreen. Study Characteristics Results Conclusion Study 1: Use of Topical Sunscreens and the Risk of Malignant Melanoma: A Meta-Analysis of 9067 Patients From 11 Case-Control Studies. The study is a general variance based meta-analysis of epidemiological studies (1966-99) to establish that use of topical sunscreen preparation increase risk of malignant melanoma. The meta analysis was done on data used form 11 studies which gave a pool of 9067 patients above 18 years of age. The combined studies gave a relative risk of 1.11 which was not significant The available epidemiological data does not show any association between use of topical sunscreen and increased risk of melanoma. Study 2: Sunscreen And New Nevi In Children: A Clinical Trial The study is a randomized controlled experiment done by researchers in British Columbia to see if there whether broad-spectrum high-sun protection factor (SPF) sunscreen use might attenuate the number of new nevi that develop in white children. The study was conducted in 1993 using a sample of 458 Vancouver schoolchildren (drawn from grades 1 and 4). The sample was divided into two groups through random selection. The test group was assigned to use an SPF 30 sunscreen with instructions of use to the parents while the control group was neither given a sunscreen nor advice about using sunscreen it. . The researchers examined the number of nevi at the start of the experiment and the number of nevi at the end of three years. The final study group of 309 children excluded non-white children and those who were lost to follow-up. The test group had developed a median of 24 new nevi while the control group had developed a median of 28 new nevi which was an insignificant difference (p=0.048). “However, the presence of freckles at baseline made a difference: While children without freckles would have little advantage from sunscreen use, the authors estimated that among first-graders with freckles, sunscreen would reduce new nevi by 40% over the study period, and among fourth-graders it would reduce nevi by 30%. Further, it appeared that children who used the most sunscreen had the fewest new nevi.” The authors conclude that "our data indicate that broad-spectrum sunscreens may attenuate the number of nevi in white children, especially if they have freckles." (Gallgher RP et al: JAMA, Jun 14 2000; 283:2955-2960) Study 3: Examination of Cognitive Variables Relative to Sunscreen Use The study aims to examine the psychological variables relative to a sun-damage preventive behavior (specifically use of sunscreen). The survey tool was a questionnaire that was administered to a sample of 230 subjects who were recruited from psychology classes in Northwstern city in USA in Fall 1996. The psychological variables that were measured in relations to the sunscreen use were perceived need, perceived consequences, perceived efficacy and social normative influence. The study discovered a significant relationship between various situational factors and perceived need (p < 0.01). Temperature has the strongest effect [F(1,99) = 253.82, η2 = 0.14], the second strongest effect was of weather [F(1,99) = 98.96, η2 = 0.06] and the third strongest effect was of time of day F(1,99) = 80.67, η2 = 0.05]. A significant relationship between sunscreen use and all the cognitive factors measures studied was also uncovered (p < 0.01). With perceived need external, perceived need internal, perceived efficacy, perceived health related consequences and social-normative influence having a r value of 0.69, 0.26, 0.85, 0.48, 0.41 and 0.22. On further analysis if was found that general sunscreen knowledge and specific knowledge both were significantly related to increased sunscreen use (r = 0.63 and 0.44 respectively p < 0.05) and that there was a significant relationship between perceived efficacy and general and specific knowledge (r =0.56 and 0.21 respectively). The perceived need to use sunscreen is effected by situational factors (temperature, weather and time of day). People are more likely to use sunscreen in higher temperature than lower temperature, they are more likely to use sunscreen when it is sunny than when it is cloudy and they are more likely to use sunscreen in the noon than at any other time, the first factor having the most effect and the last having the least effect on the use of sunscreen. A higher perceived need from external factors, perceived need from internal factors, perceived efficacy, perceived health related consequences and social-normative influence increase the chance of use of sunscreen with perceived efficacy having the most effect. Finally people with more knowledge about sunscreen are more likely to use it and perceived efficacy of sunscreen increases with more knowledge about sunscreen Study 4: Sunbathing Habits And Sunscreen Use Among White Adults: Results of a National Survey A general population telephone survey was conducted in July-September 1991 to asses the level of sunbathing and sunscreen use in United States. The survey sample was 2459 adult (16 years or older) whites. The survey was conducted simultaneously with another study that examined the relationship between aquatic activities and risk factors associated to drowning. 59 % adults reported sunbathing during the past 25% of which reported frequent sunbathing (11 or more days in the past year). Of the respondents who reported sunbathing in the previous month, 47% reported routine (always or frequent) use of sunscreen. Of these 47%, 50% used SPF above 15 or higher. Women and younger correspondents sunbathed most frequently. Women were also more likely to report routine sunscreen use than men. Respondents with the lowest educational level and those in the youngest age group (16-25 years) were less likely to use sunscreen routinely than other age groups and were also less likely to use sunscreen of protection factor of 15 or higher than the rest of the population. The study concludes that men with lower educational level and those in the youngest age group are less frequent users of sunscreen compared to the whole population. The use of sunscreen with the appropriate SPF is the least likely in respondents of the youngest group. Thus there is a need for increasing awareness about sunscreen as a protection against the sun. There is also a need to educate people about the appropriate use of sunscreen. Study 5: Summer Sunburn and Sun Exposure Among US youths ages 11 to 18: National Prevalence and Associated Factors The study aimed to find out the magnitude and patterns of sun exposure and the protective behavior amongst US youth (between the ages of 11 and18). The study was conducted in July-October 1998 as a telephonic survey of a randomized sample of 1192 youths in 48 states excluding Alaska and Hawaii. 72% of the youths reported that they had at least one sunburn, 30% reported that they had at least 3 sunburns and 12% reported that they had 5 sunburns. 39% of the youths reported that they had used sunscreen of SPF 15 or above prior to their most serious sunburn. Respondents aged between 11 to 13, girls and respondents with high sun sensitivity were more likely to use sunscreen than the rest of the sample. The number of youths exposed to sunburns is very high. More than one-third of the respondents reported the use of sunscreen of SPF 15 or above prior to getting their most serious sunburn. This shows that there is a chance that the selected population of people 11-18 years of age are not aware of the proper use of sunscreen. Study 6: Sunscreens, Safety, Efficacy and Appropriate use The study is based on meta-data analysis and includes researches which have been done on the how and why of sunscreen safety, efficacy and its proper usage. The data has been taken from a total of fifty seven studies. The article discusses the classification of sunscreens, the tolerability and efficiency of the different sunscreens available in the market on which research has been done and how to go about using the sunscreens and what precautions to take. Physical or inorganic sunscreens are supposed to be safer than their organic counterparts and they provide some protection from the UVA radiations and visible radiations which the organic sunscreens fail to do. A large number of sunscreens made of chemicals can cause photo allergies but the number of such incidents is less. Three important factors to judge the quality of a sunscreen have been outlined. Firstly, the amount of protection that the sunscreen provides from the UVA radiations, secondly, the extent to which a sunscreen is water resistant and lastly, the extent to which a sunscreen can prevent painful sunburns or erythema. Study 7: Cutaneous malignant melanoma, sun exposure and sunscreen use: epidemiological evidence The research is based on case control studies in four categories: 1. Studies whose methodology did not allow the researchers to come to a conclusion because of major bias 2. Studies evidencing no association between sunscreen use and melanoma 3. Studies evidencing a negative association between sunscreen use and melanoma 4. Studies evidencing a positive association. Some Other epidemiological studies have also been included in the article. In the first category of research, a total of six studies were included out of which two had a potential bias hence, they were excluded form further analysis. The remaining four did not allow for further multivariate analysis to be done on their data hence, they were also excluded. In the second category, there were three studies all of which showed that there is no link between sunscreen and melanoma. In the third category, there were two studies both of which showed that there is a protective effect of sunscreens. In the last category, there were three studies all which resulted in proving that usage of sunscreens exposes people to melanoma. But in the last category of studies, according to the researchers there was a large degree of bias. The effects of sunscreens and other factors causing melanoma can not be isolated due to their strong relationship. Moreover, sunscreens are not being properly used and when a sunscreen mentions that it provides effective protection then this cannot imply protection form melanoma. Moreover, the usage of sunscreen encourages people to feel safe thus, increasing risky behavior. Study 8: Ultraviolet a Radiation Suppresses an Established Immune Response: Implications for Sunscreen Design This research is based on determining the extent to which immune response is affected by UVA radiation. For this study, a specific breed of female mice was obtained from the National Cancer Institute. These mice were subjected to ultraviolet radiations and immune response deterioration was measured. The results obtained form this study confirmed the hypothesis that ultraviolet A radiation weakens immunological memory. The researchers reached the following conclusions which they have presented in the article: When a person is exposed to the sun’s ultraviolet radiations, they tend to suppress his immunological memory. Moreover, UVA radiations which are a part of the sun’s UV radiations when taken alone are sufficient enough to suppress this immunological memory. This means that sunscreens should include components which can help in blocking the UVA radiations so as to minimize their effects. Study 9: Sunscreen use and the risk for melanoma: A quantitative review This research article is a meta-data analysis of eighteen different researches done on the topic of sunscreen and how it can cause melanoma. Out of these eighteen studies, nine were population based case control studies, seven were non-population based studies and the remaining two were case control studies. The studies included were conducted during the period starting from 1983 to 2002 mostly in the United States and Europe. The authors assessed the quality of these researches by developing a scoring system. Then the statistical analysis of the studies included was performed using either a fixed-effects or random-effects model. The result for this meta-data analysis found no proof of any link between sunscreen usage and increased risk of melanoma. Rather some of the studies showed that sunscreen usage reduced the risk for melanoma. However, certain problems have limited the scope of the results found and also, most of the studies were conducted before waterproof sunscreens and those protecting from ultraviolet A were developed. The controversy which aroused regarding the risk of malignant melanoma that sunscreen users were exposed to is incorrect and has been proven wrong by this research. This research concludes that no relationship exists between sunscreen usage and the risk for melanoma. According to the authors, the previous researchers who found a positive relation between sunscreen use and melanoma was due to the uncontrollable factors. Study 10: Sunscreens and Melanoma: The future looks bright This research article is a meta-data analysis of those observational case control studies which have established that no relationship exists between malignant melanoma and the use of sunscreens. A total of fifteen studies were examined to address the issue. These studies all belong to the era of 1990. Out of the fifteen studies, four found that there is little evidence to prove that sunscreen raises the risk of melanoma, three studies showed that there is a negative relationship between sunscreen and melanoma meaning that using sunscreen reduces that risk for melanoma and the remaining studies established a positive relationship between sunscreen use and the risk for melanoma. The authors suggest that in recent years the composition and focus of the sunscreens has shifted towards higher SPF (Su Protection Factor) and a large number of sunscreens are water resistant as well. This may cause people to believe that they are better protected form the sun and hence, spend more time under the sun again increasing the risk for skin diseases. Discussion Melanoma is attributed to increased exposure to sun. It would be expected that decreasing the exposure thorough use of sunscreen would decrease the risk of melanoma. Many studies however have claimed it is the other way i.e. the use of sunscreen increased the chance of melanoma development. A meta-analysis of such epidemiological studies was done which showed no significant relationship between the use of sunscreen and risk of melanoma. Sunbathing results in an increased exposure to the sun and therefore it requires the use of sunscreen of SPF 15 or above. The use of sunscreen has also been thoroughly studied. One of these studies showed that sunbathing is a common practice through out US. However the use of sunscreen is not that common. Much less common is the use of sunscreen with the prescribed SPF of 15 or above. The appropriate use of sunscreen is most common amongst men with lower educational level or youngster between the age of 16-25 who may be the most exposed to the sun. The study concludes that men with lower educational level and those in the youngest age group are less frequent users of sunscreen compared to the whole population. The use of sunscreen with the appropriate SPF is the least likely in respondents of the youngest group. Thus there is a need for increasing awareness about sunscreen as a protection against the sun. There is also a need to educate people about the appropriate use of sunscreen. The use of sunscreen has also been studied by a cognitive perspective which has shown that use of sunscreen is positively related to perceived need, perceived efficacy, perceived health related consequences and social-normative influence. Amongst this perceived efficacy was the most highly related. It was also found that more information about sunscreen increased the perceived efficacy of respondents. It was also found that situational factors such as temperature, weather and time of day also effects people’s use of sunscreen. Unfortunately, such tendencies lead to people ignoring the use of sunscreen for example of a cloudy day, even though use of sunscreen would have been better. Thus awareness must be created amongst people to emphasis the importance of the appropriate use of sunscreen. Studies have shown that children tend to be exposed to the sun much more than adults. Therefore a large number of studies examine the use of sunscreen amongst youth and its effects on their tendency to develop melanoma. A study has shown that it is very common amongst of youngsters between the age of 11 and 18 to get sunburns. It was also found that a lot of youngsters who got sunburns were using sunscreen of SPF 15+. Obviously these youth were not using the sunscreen properly it was either ‘too little, too late, inadequate coverage, inconsistent use, or failure to reapply’. Therefore there is a definite need to educate the youth about the proper use of sunscreen. Melanocytic nevi are strongly associated with the increased risk of developing melanoma. Sunlight exposure is a major factor that results in development of nevi. A study done on school going children of grade 1 to 4, showed that use of sunscreen of SPF 30+ may reduce the development of nevi in children especially amongst those children who have freckles. The analysis of the characters, results and conclusions formulated by these studies shows that majority of the researches conducted have failed to provide a strong evidence showing a positive relation between the use of sunscreen and melanoma. All those studies which have shown such a relation have been disregarded by the researches based on the fact that they have not controlled confounding variables for instance, a lot of such studies have not taken into account the fact that a lot of people using sunscreens will be those who have sensitive skin (like those with a fair skin) and are at higher risk of developing melanoma than those who do not have a sensitive skin. These researches agree on the fact that it is difficult to isolate the effects of sunscreen and other factors that can cause melanoma. Hence, this situation makes it difficult to prove that sunscreens are or are not the cause of malignant melanoma. Moreover, a comparison of the characteristics of these studies shows that a lot them included a meta-data analysis of researches which had a major bias due to lack of control of confounding variables. This implies that it is difficult to collect accurate data from the population under study regarding their sunscreen usage habits. The researches are of a common conclusion that sunscreen usage does not increase the risk for melanoma but none of them speaks either about the high SPF and waterproof sunscreens or about those sunscreens which provide protection from UVA radiations. It is unclear whether these sunscreens can have a different effect on their users because they are made of different chemicals and provide some extra protection. Problems and Potential Biases Use of Topical Sunscreens and the Risk of Malignant Melanoma The major problem with the meta-analysis is that the data used is highly heterogeneous which has reduced its credibility. Examination of Cognitive Variables Relative to Sunscreen Use This study measures variable which are all self report. Thus respondent bias may effect the results and validity of the study. Also the sample selection is not random which may not be a true representation of the population Sunbathing Habits And Sunscreen Use Among White Adults and Summer Sunburn and Sun Exposure Among US youths ages 11 to 18 Both these surveys depend on measures that are entirely self-reported and hence open a chance for respondent biases. Most likely is the presence of recall bias in the telephonic survey as the respondents are asked to recall the number of times they have sunbathed, the frequency of use of sunscreen etc. The recall bias may be higher for the study conducted on 11 to 18 year olds. Sunscreen And New Nevi In Children: A Clinical Trial The clinical trial is conducted on a sample that has not been randomly selected and therefore loses some of its credibility due to the existence of sample bias. Sunscreens, Safety, Efficacy and Appropriate use The authors says that although a lot of research has been conducted in this area, still we are not sure of the relationship between the sun’s UV radiations, sunscreens and malignant skin diseases such as melanoma. Also, he mentions the presence of confounding variables and recall bias act to distort research results. Also, he says that it may not only be just the sunscreen usage that has led to an increased rate of melanoma but one should also, look at the changing lifestyles of the people and how the number of outdoor activities have increased over the past few decades. These are also responsible for malignant skin cancers but researchers have failed to take them into account. Cutaneous malignant melanoma, sun exposure and sunscreen use: epidemiological evidence The author points out that the research has been done using hospital controls which may have introduced a bias because using dermatological patients rather than human beings in general can give biased results. He further says that questions which are difficult to quantify also introduce a bias. For instance, questions which have answers like “sometimes”, “often”, “a lot of times” etc. distort the accuracy of the questionnaire. The researchers are never sure when asking questions about the past behavior of the people because people may not necessarily remember it correctly. Also, it is not necessary that these people will admit their actual usage when asked by an unknown person. However, the authors give future researchers guidelines on how to minimize these biases and take their research to a further higher level. Sunscreen use and the risk for melanoma: A quantitative review The authors mention that they received heterogeneous results from their studies which are a probable result of asking questions which are hard to quantify and also, they are such type of questions which force a respondent to give some or the other reply. However, analyzing such heterogeneous studies can put a limit on the amount and extent of analysis that can be performed upon them. Initially, the authors included studied which included people with a history of sunburns and used sunscreens for the treatment of those sunburns thus, introducing a bias. But afterwards these studies were excluded form the analysis. Moreover, when people use sunscreens they feel protected from the sun’s ultraviolet radiations thus, spending more time under the sun and increasing the risk for melanoma making it difficult for the researchers to estimate the extent to which the sunscreen is responsible for the carcinogenic disease and inducing a bias in the research results. Sunscreens and Melanoma: The future looks bright In this research article also, the authors mention that the presence of positive and negative confounding variables acts to distort the results. Then they go on to say that the thickness of the application is also a major factor impacting the extent to which a sunscreen can provide protection from the sun’s ultraviolet rays. The thickness combined with the uniformity of application, resistance of the sunscreen in water and sand absorption play a vital role in determining the amount of protection that a sunscreen can provide. When people are asked about how one sunscreen provides better protection than the other, they do not keep these things in mind distorting the survey results. Methodological Strengths and Weaknesses Use of Topical Sunscreens and the Risk of Malignant Melanoma The meta-analysis has been done after an extensive literature research and has made a final selection of studies based on a pre-defined inclusion criteria that does not have much room for selection biases. This criteria has insured in turn that no studies are selected which have baises withen them for example in the form of respondent bais or sample bais. The meta-analysis has also tested the data for hetrogenity and tried to eliminate most of the hetrogenious data to increase the credibility of the study. Sunbathing Habits And Sunscreen Use Among White Adults and Summer Sunburn and Sun Exposure Among US youths ages 11 to 18 The telephonic survey that aimed to examine the amount of sunburns in youth and their use of sunscreen conducted it directly with youth instead of their parents. This has an obvious advantage because parents may not observe the use of sunscreen in children very closley. Also this telephonic survey and the other one on the sunbathing habits and use of sunscreen among white adults was based on a national level and was conducted through random dialing. In combination these two factors resulted in a trurly representative sample of the population. However the effect of respondent bias is still present in both the studies like any other study that uses self report errors. The authors have not mentioned any methods through which they tried to eliminate these biases. Sunscreen and New Nevi in Children: A Clinical Trial In this study the authors avoid the use of self-report method and take measurements by themselves thus eliminating respondent biases. However the sample they have selected is not randomly selected and hence cannot be termed as a true representation of the population. Examination of Cognitive Variables Relative to Sunscreen Use Finally, the study examining the coginative variables has been built in the context of a well-developed cognitive-behaviorial decision theory and also allow for multi-variant analysis. The researchers have made deliberate efforts to reduce the chance respondent bais especially due to social disirabilty as all the measures are self-report. They have done so by emphasizing the importance of honest answers to the respondents. The the realiabilty and validity of the measures were also tested against 20-item Good Impression Scale from California Psycological Inventory (Gough 1957) showing that influence of social desirability was minimal in the measures. Sunscreens, Safety, Efficacy and Appropriate use The strength of the study includes that all the evidences are strong based o the fact that the authors have conducted an analysis of fifty seven studies. It is the only study included here which given a full analysis of various chemical components on which different types of sunscreens are based and the pros and cons of these various types of sunscreens. Its major weakness is that it has not given a details of how and what studies were selected for the research, the criteria on which such selection was based. Moreover, the authors have not done any comparative analysis of these studies so as to determine how these researches positively or negatively relate to each other. Cutaneous malignant melanoma, sun exposure and sunscreen use: epidemiological evidence The research’s strong point unlike the one analyzed before it is that it has tried to determine biases present there in the studies conducted and the biases have been presented in the article. Also, the article gives direction to future studies and advises them to be careful of the various confounding factors which have biased the results of these studies and the many done before it. The weakness is that proper controls were not established which have resulted in heterogeneity among the results of different studies involved. Ultraviolet A Radiation Suppresses an Established Immune Response: Implications for Sunscreen Design: The research results are based on strong medical and statistical evidence which have been presented in the study. The fact that no implications for the study result have been mentioned threatens the chances of any follow ups being done on this study. Sunscreen use and the risk for melanoma: A quantitative review: The study has a very strong point that all of the researches that have been included here have been based on pre-planned selection criteria. Moreover, to maintain the quality of studies included in the research, the authors have set a quality-assessment scoring system. Here, also no implications have been provided to guide future researchers as to what they should look for in their researches. Sunscreens and Melanoma: The future looks bright: The studies included in the meta-data analysis have not been based on a properly decided upon selection criteria. Also, the confounding variables, both positive and negative have played their part in distorting the result of the study. Conclusion A significant point that must be mentioned in conclusion is that the various studies that conclude that use of sunscreen increases the risk of melanoma are prone to various biases. Meta-analysis after excluding such studies proves that this claim is incorrect. Secondly, people have to be educated about the need and use of sunscreen especially children who are usually the most vulnerable to the sun exposure. Reference Huncharek, M. and Kupelnick, B. 2002. Use of Topical Sunscreens and the Risk of Malignant Melanoma: a meta-analysis of 9067 patients from 11 case-control studies. American Journal of Public Health. Vol. 92 Issue 7 Gallagher R. P., Rivers J. K., Lee T. K.,Bajdik C. D., McLean, D. I. and Andrew J. Coldman, A. J. 2000. Sunscreen And New Nevi In Children: A Clinical Trial. Pediatric Alert. Vol. 25, Issue 13 Koh, H. K, Bak, S. M., Geller, A. C.,Mangione, T. W., Hingson, R. W. Levenson, S. M. Miller, Donald R., Lew, R. A. and Howland, J. 1997. Sunbathing Habits and Sunscreen Use among White Adults: results of a national survey. American Journal of Public Health Davis, K. J., Cokkinides, V. E., O'Connell, M. C., Wingo, P. A. and Weinstock, M. A. 2002. Sumer Sunburn and Sun Exposure Amoung US Youth Ages 11 to 18: national prevalence and associated factors. Pediatrics. Vol. 110, Issue 1 Turrist, R. Hillhouse, J. Gerbert, C. and Grimes J. 1999. Examination of Cognitive Variables Relavant to Sunscreen Use. Journal of Behavioral Medicene. Vol 22 Issue. 5 Bastuji-Garan, S. and Diepgen, T. 2002. Cutaneous Malignant Melanoma, Sun Exposure, and Sunscreen Use: epidemiological evidence. British Journal of Dermatology. Dennis, L., Freeman, L. and VanBeek M. 2003. Sunscreen Use and the Risk for Melanoma: a quantitative review. Annals of Internal Medicine. Diffey, L. 2005. Sunscreens and Melanoma: the future looks bright. British Journal of Dermatology. Moloney, F., Collins, S. and Murphy, G.2002. Sunscreens: safety, efficacy and appropriate use. Am J Clin Dermatol. Nghiem, D. et Al. 2001. Ultraviolet A Radiation Suppresses an Established Immune Response: Implications for Sunscreen Design. The Society for Investigative Dermatology, Inc. Gough, C. G. 1957. California Personality Inventory. Psychologist Press, Palo Alto Read More