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Does Sunscreen Cause or Heighten the Chances of Skin Cancer?

Erin Dugan

February 16, 2009

Does Sunscreen Cause or Heighten the Chances of Skin Cancer?

            The recent debate over sunscreen and the possibility of it being linked to the development of skin cancer has caused much controversy in modern society, and knowledge of this issue continues to expand. The objective of this review to is provide a solid background of the different types of skin cancer and the traditional causes of these diseases and then to explain both sides of the argument over the connection between sunscreen and skin cancer. After interpretation, comprehension, and analysis of the data and information, it should be possible to answer the following: Does sunscreen have a connection to skin cancer? Is there sufficient evidence to support such a claim? Are there other confounding variables that are too significant to remove or that have too much of an effect to allow a reasonable evaluation?

The History and Epidemiology of Skin Cancer

The three major types of skin cancer include basal cell carcinoma, squamous cell carcinoma, and malignant melanoma (Larsen, 1994).  “Basal cell carcinoma is the most common form of skin cancer,” and it “occurs most frequently in men who spend a great deal of time outdoors and primarily produces lesions on the head and neck” (Larsen, 1994). According to Larsen, squamous cell carcinoma, associated with fair-skinned, blue-eyed persons with red or blonde hair who do not tan and who burn easily, is more likely to spread than basal cell carcinoma (1994).  The most dangerous and rarest type of skin cancer is malignant melanoma, known for attacking the cells that produce melanin (Larsen, 1994). “It does not necessarily occur on sun-exposed areas of the body and is thought to be linked to brief, intense periods of sun exposure and a history of severe sunburn in childhood or adolescence. Malignant melanoma metastasizes easily and is often fatal if not caught in time” (Larsen, 1994).

In Order: Basal Cell Carcinoma, Squamous Cell Carcinoma, Melanoma (AAD, 2008)

Traditionally Accepted Causes of Skin Cancer

Traditionally, researchers and scientists have associated the development of skin cancer with ultraviolet radiation and sun exposure.   According to the American Cancer Society, “many of more that one million skin cancers diagnosed each year could be prevented with protection from the sun’s rays” (American Academy of Dermatology [AAD], 2008).  Over exposure to the sun’s ultraviolet rays can lead to damage in the actual DNA of the skin, and, with cumulative exposure and lack of repair time, the damaged DNA and develop into cancer (AAD, 2008).  However, it is also important to note that a person can be genetically predisposed to skin cancer and that “between 5% and 10% of melanomas develop in people with a family history of melanoma” (AAD, 2008).

Rising Incidence Rates

Unfortunately, the rates of skin cancer are steadily continuing to rise (AAD, 2008).  Although people are becoming much more informed about the dangers and potential health threats that can come from over exposure to the sun, the use of protective measures against the harmful ultraviolet radiation do not seem to be rising significantly (AAD, 2008).  According to the research of the American Academy of Dermatology, “more than one million nonmelanoma skin cancers are diagnosed each year, and approximately one person dies from melanoma every hour” (2008).  The research also estimates that if the trends continue at this same alarming rate, then approximately one out of every five Americans will develop skin cancer (AAD, 2008).  The information and research data collected from the American Academy of Dermatology seems to be of high quality because the purpose of the organization is not to support any particular business or collect any kind of monetary compensation or profit. Instead, the organization is centered around educating the public as well as improving the understanding and practice of dermatology (AAD, 2008).

Similarly, in a study aimed at discussing “current epidemiologic data concerning the incidence, morbidity, environmental influences, predisposing, host conditions, precursor lesions, and prevention of melanoma and nonmelanoma (basal and squamous cell) skin cancer,” Gloster and Brodland found that the incidence and prevalence of skin cancer is rising quickly (1996). The researchers concluded that “although the mortality rate for nonmelanoma skin cancer is decreasing, that of melanoma is increasing, and also that both are associated with significant morbidity”  (Gloster & Brodland, 1996).  Unlike the other two common types of skin cancer that are believed to be the result of chronic sun exposure, melanoma does not seem to have any direct link to ultraviolet radiation (Gloster & Brodland, 1996).  

The Prevention of Skin Cancer

According to the study constructed by Gloster and Brodland in reference to skin cancer, “prognosis improves with early detection” (1996).  The particular source encourages the prevention of skin cancer through the education of parents and physicians on how the accurately identify the disease. In addition, the article encourages people to drastically minimize, or completely eradicate, exposure to ultraviolet radiation (Gloster & Broland, 1996).  This suggestion clearly follows the popular belief that avoidance of and protection against sun exposure is the best and most reliable method in the prevention of all types of skin cancer. However, less traditional theories claiming that restricting sun exposure is not effective in preventing skin cancer do exist. Veronique Bataille and Ester de Vries conducted a study from which they concluded that “a reduction in people’s exposure to sun has not lead to a significant reduction in the incidence of melanoma” (2008).  Futhermore, “they believe that sun avoidance may be detrimental and stress that secondary prevention with early detection of melanoma saves lives” (Bataille & Vries, 2008).

The Benefits of Using Sunscreen

As previously stated, the most widespread and accepted measure for the prevention of skin cancer is the avoidance of sun exposure as well as protective measures against its harmful rays through use of sunscreen.  An article published in the Journal of Drugs in Dermatology and approved and reprinted by the Skin Cancer Foundation, firmly rejected that claim that sunscreen plays any direct role in the development of skin cancer (2004).  However, some of the researchers standing behind this claim did provide reasonable hypotheses as to why sunscreen could increase the risk for melanoma (JDD, 2004).  The Journal of Drugs in Dermatology (2004) found that some of these explanations include that:

     certain substances in sunscreen may produce a carcinogenic reaction when exposed to

     the sun, that sunscreens do not provide adequate, measurable protection against the

     sun's ultraviolet A rays, and that, by preventing sunburn, sunscreen use encourages

     light-skinned, melanoma-prone people to stay out in the sun longer, ultimately

     increasing their DNA damage. (para. 3). 

Yet, none of these theories have been proven at this point in time.

Studies Rejecting the Claim that Sunscreen Causes Skin Cancer

After being reviewed by Leslie K. Dennis PhD, eighteen previous administered studies that allowed many researchers to draw false conclusions about the connection between sunscreen and skin cancer were questioned and recalled (JDD, 2004).  The errors in the procedure of these studies included failure to “take into account that the people most likely to use sunscreen are those who are naturally sensitive to sunlight and therefore more predisposed to melanoma--such as those with fair skin and freckles and also the dependence on the subjects to accurately and precisely recall their history of sunscreen use and application over a long period of time (JDD, 2004). In addition, the article’s (2004) dismissal of the fact that sunscreen use can “encourage people to stay out in the sun longer, thereby incurring more damage,” and disregard toward the difference between modern sunscreen and older sunscreen undoubtedly affected the outcome of these experiments at the University of Iowa (JDD).  Thus, after evaluating this study, Darrell S Rigel MD concluded that “the ability of sunscreens to help prevent skin precancers and potentially nonmelanoma skin cancers is ample reason to use them” and also that “there is no proof that sunscreens cause cancer” (JDD, 2004, para. 9). Rigel related the risk of melanoma to the frequency and the intensity of sunburns in one’s lifetime, and he claims to openly encourage his patients to use sunscreen in order to reduce the risk and severity of sunburn (JDD, 2004).

The Risks of Using Sunscreen

Conversely, recent studies and stories in the press have begun to cause a controversial debate over whether or not sunscreen is an effective skin cancer prevention method or a potential risk factor in the development of skin cancer. An article written by Mary Powers (2008) explains Robert J. Davis’ book and his position on the use of sunscreen in the prevention of cancer.  Davis concentrates on the public’s tendency to adhere to advice without questioning its validity (Powers, 2008). He states that sunscreen is indeed important in the prevention of sunburn and squamous cell cancer but goes on to say that no irrefutable evidence exists that claims that sunscreen is efficient in protection against melanoma (Powers, 2008).  The article (2008) demonstrates that the danger of sunscreen use in the development of melanoma is that the majority of consumers “cite wearing sunscreen as the most important thing they do to protect themselves against skin cancer” rather than as a second line of defense (against skin cancer) after taking steps to minimize your time in the sun, especially during peak hours, and to wear a wide-brimmed hat, sunglasses and protective clothing” (Powers, para. 21). 

In addition to these important assertions, the article brings up a new topic of interest when Davis says, "I think it is no coincidence that if you look at where the money comes from (to promote sunscreen use), these groups have an incentive not to tell us the full truth about the unknowns about sunscreen” (Powers, 2008, para. 22). Robert Davis’ evidence and perspectives seem to be unbiased and straightforward. His professions as a teacher at Atlanta’s Emory’s Rollins School of Public Health, the president/ editor-in-chief of a consumer health information distributing company called Everwell, and the producer of a series on PBS entitled “Health Week” all provide a stable argument that his claims are impartial and fair-minded (Powers, 2008).

Connection Between Sunscreen and Cancer

Furthermore, in Larsen’s article (1994) a connection is formed between the use of sunscreen in Queensland, where the medical establishment has long and vigorously promoted the use of sunscreens, and the incidence of melanoma per capita. The article states “the greatest rise in melanoma has been experienced in countries where chemical sunscreens have been heavily promoted” (Larsen, 1994, para. 4). Drs. Cedric and Frank Garland of the University of California are two strong opponents of chemical sunscreens and have pointed out that “although sunscreens do protect against sunburn, there is no scientific proof that they protect against melanoma or basal cell carcinoma in humans (1994, para. 5). There is, however, some evidence that regular use of sunscreens helps prevent the formation of actinic keratoses, the precursors of squamous cell carcinoma” (Larsen, 1994, para. 5). Thus, these two respected doctors make confident claims that using chemical sunscreens can ironically lead to the development of skin cancer (Larsen, 1994). However, it is not necessarily only the chemicals themselves that create a problem, but also the tendency of humans to “develop a false sense of security” about the degree of protection that sunscreen provides (Larsen, 1994, para. 6).

Studies Supporting the Claim that Sunscreen Causes Skin Cancer

In one of Larsen’s publication, he describes the efforts of three European cancer research institutes that decided to challenge the “conventional medical wisdom that the liberal use of sunscreens helps prevent skin cancer and melanoma” (2002). With the conclusion of this study, these three cancer institutes confidently believed and stated that there is an unmistakable connection “between sunscreen and the risk of developing melanoma” (Larsen, 2002). For this study, 631 European children in their first year of grade school were selected, and their parents were surveyed and interviewed in order “to determine their child's use of sunscreens and protective clothing and the amount of sun exposure they were exposed to - particularly during annual holidays” (Larsen, 2002). In his description on the study, Larsen states that one way that the researchers evaluated the children was by counting each child’s moles, which are also called nevi and are thought to be associated with melanoma based on previously performed research. As the article describing the study states,

After evaluating each child appropriately and reviewing the data,

the researchers found that the children who habitually used sunscreens had a 68 per cent higher nevus count than did the children who never used sunscreens. This increased risk remained after adjusting for such other variables as skin type, eye colour, and extent of sun exposure. Wearing protective clothing when in the sun was associated with a 41 per cent lower nevus count. (Larsen, 2002).

In addition to these significant results, the researchers discovered that neither the SPF, or strength, of sunscreen nor the accumulative occurrence of sunburn in the children were in any way associated directly with nevus count. Larsen even continues on to disclose that “the highest risk associated with sunscreen use was found among children who had never experienced a sunburn” (2002). With these discoveries, the researchers were able to come to the conclusion that sunscreen can lead to nonchalant attitudes toward prolonged sun exposure, and, thus, a higher risk of skin cancer development (Larsen, 2002).

Conclusion

In closing, the evaluation and comparison of the types of cancer, the traits and causes associated with them, and the risks and benefits of sunscreen use made it possible to evaluate the issue. It does seem clear that there is a link between sunscreen use and skin cancer in humans. The studies clearly displayed a recognizable pattern between the use of the product and the incidence of different types of skin cancer. However, despite the fact that there is a connection, there is not enough evidence to claim that the use of sunscreen or the products’ chemical components are themselves risk factors for the disease. Confounding variables that are too significant to remove, such as the change in levels of confidence towards personal immunity to skin damage after using sunscreen, could have an undeniable effect on the experiment. Such a variable is difficult to test and could completely alter the results of any experiment to test the connection. Although these results and data may not be sufficient to abandon the use of sunscreen completely, they do bring heightened awareness to the dangers of sun exposure.  Not only do the results that were found encourage the use of more protective, precautionary measures to decrease sun exposure, they simultaneously challenge unconcerned modern attitudes towards the sun and its potential harmful effects.

 

 

 

 

 

 

References

American Academy of Dermatology. (2008). What is skin cancer? Retrieved February

15, 2009, from http://www.skincarephysicians.com/skincancernet/whatis.html

 

Bataille, V., & Vries, E. (2008). Melanoma—Part 1: Epidemiology, risk factors, and

prevention. BMJ, 337, 2249. doi:10.1136/bmj.a2249

 

Journal of Drugs in Dermatology. (2004). Does sunscreen cause melanoma? Researchers

now strongly say no. Retrieved February 16, 2009,

from http://findarticles.com/p/articles/mi_m0PDG/is_3_3/ai_n6056512

 

Gloster, H. M., & Brodland, D. G. (1996). The epidemiology of skin cancer. Dermatol

Surg., 22, 217-226. Received February, 14, 2009, from PubMed.

 

Larsen, H. R. (1994). Sunscreens and Cancer. International Journal of Alternative &

Complementary Medicine, 12, 17-19. Retrieved February, 15, 2009, from

www.yourhealthbase.com

 

Larsen, H. R. (2002). Do sunscreens promote melanoma? Victoria, BC: International

Health News Database. Retrieved February 13, 2009, from

http://www.yourhealthbase.com/database/a88f.htm

 

Power, M. (2008, July 28). Think wearing sunscreen protects you from skin cancer?

Think again. The Commercial Appeal. Retrieved from http://www.commercialappeal.com/news/2008/jul/28/hype-buster/

American Academy of Dermatology

 

 

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