The Importance of Primary and Secondary Prevention Programs for Skin Cancer

Key Points

As the US population of adults 65 and older increases, the number of people developing and dying from new skin cancers will rise.
Skin self-examination (SSE) with the assistance of a partner may achieve some reduction in the estimated 8400 deaths from cutaneous melanoma (CM) and reduce the physical and emotional burden of non-melanoma skin cancer (NMSC) and CM.
Technologic advances, such as computer-assisted screening of the high-risk population, improve physician detection of early melanoma.
The role of parents in adolescent health and disease prevention is very influential. Parents may reframe the sun protection health promotion message with their children to, ‘Daily sun protection now means fewer or no painful burns. Tanning now means loss of the skin's health and beauty; you may get wrinkles in your 20s.’

Introduction

Skin cancer, the most common malignancy in the United States (US), is an important public health concern with an incidence rate that will continue to increase as the US population of adults 65 and older increases. The incidence of invasive cutaneous melanoma (CM) has nearly tripled in the US between 1975 and 2004, making melanoma the sixth most common cancer in men and women in the US, with more than 68,000 cases of invasive melanoma diagnosed and almost 8700 deaths in 2010. Primary prevention programs are related to encouraging behavioral changes to lower subsequent skin cancer risk. Secondary prevention efforts focus on enhancing early detection of skin cancer. Primary prevention influences incidence while secondary prevention impacts on morbidity and mortality. While secondary prevention with early detection is an effective strategy for those who sustained unprotected sun exposure in youth, primary prevention by effective sun protection throughout life for those at risk to develop skin cancer may reduce the development of skin cancer over a lifetime.

History

The relevance of effective primary and secondary skin cancer prevention programs is becoming increasingly important as the numbers of these cancers continue to rise. Although melanoma is less common than basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), the much higher mortality of melanoma makes it a major concern as the incidence continues to increase globally by 3–7% annually. Melanoma age-adjusted incidence rates have increased by 4.1% per year since 1981. The increasing incidence of melanoma is also associated with an increased mortality in both the US and Europe. Mortality rates in the US have continued to increase from 1985 to 2004. In 2010, in the US 8700 people died of melanoma when the disease progressed to stage IV with organ metastases. In 2000, 8300 European men died out of the approximately 26,100 diagnosed with melanoma and, of 33,000 European women diagnosed with melanoma, 7600 died.

In the US, non-melanoma skin cancer (NMSC) is the most common malignant neoplasm in the Caucasian population. The incidence of NMSC is 18–20 times greater than melanoma and is increasing. Since NMSCs are usually treated in outpatient settings and are not reported to cancer registries, exact US incidence rates are not available. The crude prevalence of NMSC in the US is roughly 450 cases per 100,000 individuals. An estimated 2300 people in the US will die annually from NMSC, primarily due to metastatic cutaneous SCC. While NMSC is likely to claim fewer lives than melanoma, considerable morbidity results from treatment. Since many NMSCs arise on the frequently sun-exposed areas of the head and neck, surgical resection may result in significant disfigurement with impaired quality of life and social interaction.

Targeting prevention efforts

Personal risk factors

For prevention programs to have the greatest impact, a focus on those at greater risk must be achieved. Older age is associated with higher risk of developing NMSC. There is a rapid rise in incidence after age 40, with SCC increasing more rapidly than BCC. While the incidence for men and women are similar at early ages, after age 45, men develop NMSC two to three times more frequently than women. In the Surveillance, Epidemiology and End Results (SEER) program, 75% of the thicker melanomas with poor prognosis were in patients older than 50. Scalp/neck melanoma represented 6% of melanoma from 1992 to 2003, but 10% of deaths from melanoma. It is expected that the US population of adults 65 and older will increase as much as 20% between 2010 and 2030; therefore, the number of people with skin cancer and the number of deaths it causes can be expected to continue to rise.

Skin cancer is more common in people with immunosuppressive diseases or with diseases that are controlled by chronic immunosuppressive therapy, e.g. survivors of non-Hodgkin lymphoma, organ transplant patients, and those with rheumatoid arthritis. Among transplant recipients, the incidence of SCC is markedly increased in those with sun-sensitive skin, a history of sun exposure, and clinical signs of photoaging. NMSCs usually appear 3 to 7 years after the onset of chronic immunosuppressive therapy. Renal transplant patients with a functioning graft for more than 5 years have a relative risk of 6.5 of developing NMSC, which increases to 20 after more than 15 years. There is a 75% increased risk of CM among non-Hodgkin lymphoma survivors, and a two- to fourfold higher incidence in organ transplant recipients undergoing immunosuppressive regimens.

The considerable variability in genetic susceptibility to developing skin cancer is attributed to the melanin content of skin and the skin's ability to tan in response to ultraviolet radiation (UVR) exposure. Pale complexion, freckling, inability to tan, past severe sunburns and cumulative sun exposure, light eye color, northern European or Celtic heritage, and red or blonde hair are strong predictors of developing NMSC, and all are related to the melanin content of the individual's epidermal cells. A family history or personal history of melanoma or NMSC is associated with an increased risk of developing other skin cancers. While families with multiple affected members account for about 10% of melanoma cases, the relative contributions of genetic and shared environmental risk factors are unknown.

The familial tendency to develop NMSC is probably related to the gene MC1R (melanocortin-1 receptor), leading to red hair and sun sensitivity. For example, MC1R may identify people of color with a darker skin type that are at increased risk for melanoma. The rates of NMSC for non-Hispanic whites were approximately 11 times greater than for Hispanics, who do not share the same phenotype. NMSCs in Caucasians have a log-linear increasing incidence with age, which may be due to cumulative environmental UVR exposure ( Fig. 7.1 ).

Figure 7.1, The biologic inherited traits of the person (such as the adolescent girl with freckles over her back and shoulders) form the base upon which the individual's occupation, intensity of ultraviolet radiation in their geographic location, as well as their social and family normative beliefs regarding sun protection (such as the 90-year-old woman with a lifetime of sun protection having no freckles) are laid to establish their sun exposure behavioral patterns. After repetitive events of sunburns (young adult woman with sunburn of the chest) or chronic tanning over a period of years, skin cancer develops.

Environmental risk factors

When occupational and recreational patterns of ultraviolet light (UVL) exposure place those with genetic susceptibility in harm's way, NMSCs occur. There is a clear latitudinal gradient in incidence of NMSC. NMSCs occur more frequently in residents of areas with high solar radiation such as Australia, than in areas of low solar radiation like parts of the US. While the incidence of BCC in the US is approximately 146 per 100,000 people, the incidence is 788 cases per 100,000 people in Australia, where the average amount of sun exposure is much greater than in other parts of the world. Over the past 10–30 years, the age-adjusted incidence of cutaneous SCC has increased by 50% to 200% due to increasing long-term overexposure to UVL. , SCCs occur on sun-exposed body locations with maximum exposure, such as the head and neck, and in outdoor workers more commonly than in indoor workers.

CM and BCC have a more complex relationship with sun exposure and appear to be associated with a history of sunburns, particularly in childhood. Migration studies show a higher rate of CM in those who migrate to a sunnier climate than those who remain in their own country, particularly if migration occurs in childhood. The risk of CM is higher in indoor workers than in outdoor workers. CM is more common in body areas with intermittent light exposure. BCC has a similar distribution pattern in the trunk and lower limbs, i.e. areas not so frequently exposed.

Both NMSC and CM occur in people with actinic keratoses, sun-related precancerous lesions. Actinic keratoses can be considered a marker of past excessive sun exposure. The indoor or outdoor UVL exposure sustained by an adult in their youth places them at risk to develop melanoma and NMSC several decades later. For adults with a genetic predisposition to develop skin cancer who sustained unprotected sun exposure or deliberate tanning, death and disfigurement from surgical resection may be modified by secondary prevention.

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