Presentation on theme: "Update on skin cancer and artificial tanning Loraine Marrett May 2007."— Presentation transcript:
Update on skin cancer and artificial tanning Loraine Marrett May 2007
Outline Update on skin cancer statistics Use of tanning equipment Tanning equipment and skin cancer
Most common cancers, Ontario, 2007* 32,000 Ontarians will be diagnosed with skin cancer in 2007 1/3 of all new cancers 2,000 are melanoma Source: Canadian Cancer Statistics 2007
Melanoma incidence and mortality rates*, Ontario, 1971-2004 Incidence & mortality higher in males Incidence increasing again Following a period of decline/stability Mortality increasing steadily in both sexes Source: Cancer Care Ontario (Ontario Cancer Registry, 2007). *3-year moving averages standardized to the Canadian 1991 population.
Source: Cancer Care Ontario (Ontario Cancer Registry, 2007). * 3-year moving averages standardized to the Canadian 1991 population. Melanoma incidence rates*, by age, Ontario, males, 1971-2004 Increasing very recently in 15- 34 year olds, after long period of stability/decline Declining in 35-54 yr olds Increasing at older ages
Source: Cancer Care Ontario (Ontario Cancer Registry, 2007). * 3-year moving averages standardized to the Canadian 1991 population. Melanoma incidence rates*, by age, Ontario, females, 1971-2004 Increasing in 15-34 year olds, after a period of stability or decline Stable for 35-54 yr olds Increasing at older ages Rates much lower than for males at older ages (55+) NOTE: Rate scale is same as for males
Melanoma incidence rates*, for those <55, Ontario, by sex, 1971-2004 Source: Cancer Care Ontario (Ontario Cancer Registry, 2007). *3-year moving averages standardized to the Canadian 1991 population. Using a better scale for younger age groups, we can more clearly see trends Males and females have similar trends, but females have higher incidence
Source: Cancer Care Ontario (Ontario Cancer Registry, 2007). *3-year moving averages standardized to the Canadian 1991 population. Melanoma incidence rates*, for young adults, Ontario, by sex, 1971-2004 Rates are increasing for both 15-24 and 25-34 year olds of both sexes
Common cancers of young adults, Ontario 10% of cancers in 15-34 year olds are melanomas Tied for second rank Only thyroid cancer is more common (N=504)
Use of tanning equipment in Ontario: Adolescents (ages 13-18) In 2006, 11% of grade 11/12, 7% of grade 9-10 and 2% of grade 7-8 girls used tanning equipment in the past year 3-4% of boys had used Most did so at a tanning salon Parents pay at least some of the time for >50% of users Source: Canadian Cancer Society, Ontario Division. Skin cancer and ultraviolet radiation: Focus on artificial tanning (2007)
Why do Ontario teens use tanning equipment? Source: Youthography Inc. poll commissioned by Canadian Cancer Society, Ontario Division, October 2006.
Beliefs about tanning, tanning equipment users vs. non-users, Ontario teens Source: Youthography Inc. poll commissioned by Canadian Cancer Society, Ontario Division, October 2006.
Use of tanning equipment in Ontario: Young adults Cancer 2020 target Male, reporting PHUsFemale, reporting PHUs Source: Report on Cancer 2020 (2006). Data from Rapid Risk Factor Surveillance System for 5 PHUs (2003). In 2003, 12% of men & 29% of women aged 18-34 used tanning equipment in the past year (5 PHUs) In Canada: In 2006, 18% of females and 8% of males used tanning equipment in past year (Second National Sun Survey) Why the discrepancy? Same questions Different context Different geography Different times of year Preliminary NSS2 data only
Meta-analysis #1 1 (10 studies to April 2004) –Ever vs. never use: RR = 1.25 (95% CI: 1.05-1.49) –First use as young adult vs. never: 1.69 (95% CI: 1.32-2.18) –Later studies have results similar to earlier studies (when > UVB) Meta-analysis #2 2 (19 studies to March 2006) –Ever vs. never use: RR = 1.15 (95% CI: 1.00-1.31) –First use before age 35: 1.75 (95% CI: 1.35-2.26) Sources: 1. Gallagher et al. Cancer Epidemiol Biomarkers Prev 2005 2. IARC Working Group on artificial UV light and skin cancer. Int J Cancer 2006 Melanoma & use of tanning equipment
Squamous cell carcinoma Meta-analysis #2 1 (3 studies to March 2006) –Ever vs. never use: RR = 2.25 (95% CI: 1.08-4.70) –1 study 2 found odds ratio increased by 20% for each decade younger at first use Basal cell carcinoma Meta-analysis #2 1 (4 studies to March 2006) –Ever vs. never use: RR = 1.03 (0.56-1.90) –1 study 2 found odds ratio increased by 10% for each decade younger at first use Sources: 1. IARC Working Group on artificial UV light and skin cancer. Int J Cancer 2006 2. Karagas et al. JNCI 2002. Non-melanoma skin cancer & use of tanning equipment
Tanning equipment (TE) emits both UVB and UVA –% UVB generally somewhat less than in sunlight (about 5%) Exposure to sunlamps or sunbeds is a human carcinogen (Report on Carcinogens, National Toxicology Program, 2002) Strength of UVR may be higher than the sun per unit time, especially in the UVA range –The high doses of UVA represent a new phenomenon –Total body dose is greater - more skin area is exposed All parts of the body – whether rarely or frequently exposed to the sun - get similar exposure –Generally consistent with ‘intermittent’ exposure to rarely exposed sites like the back –Intermittent exposure to UVR is especially important in the etiology of melanoma and probably BCC Exposure to UVR early in life is particularly important to the development of melanoma Does it make sense?
The prevalence of using tanning equipment is on the rise everywhere – even in Australia! The age at first use is getting younger and younger The tanning industry has been very successful at marketing to youth, keeping use-related regulation at bay and making claims about health benefits – and emerging vitamin D evidence certainly makes their lives easier The tanned look is ‘in’ with teens I predict increases in melanoma in young adults – especially women - over the next 2 decades…. –We may already be on the way… –They are already seeing this in the US RED Act (federal) regulates equipment and marketing practices only Sobering final thoughts
Melanoma incidence rates* by age group, Ontario females Source: Cancer Care Ontario (Ontario Cancer Registry, 2007). *3-year moving averages standardized to the Canadian 1991 population. Will we see this? 2015
So what should we do? How much impact would we have, even if all the CCS (Ontario) recommendations were enacted?
Acknowledgements Sandrene ChinCheong, Cancer Care Ontario Canadian Cancer Society, Ontario Division
UVA vs. UVB in the skin UVB is 1000x more biologically active than UVA UVB is responsible for squamous cell ca of skin UVB is responsible for production of vitamin D UVB and UVA probably both play a role in melanoma UVA penetrates more deeply into the skin –14% of UVB and 50% of UVA reaches melanocytes –UVA penetrates deeper into the dermis
Melanoma & sun exposure Recent meta-analysis of epidemiologic studies “Intermittent” pattern of exposure: –Sunbathing, water sports, sunny vacations: RR = 1.6 (1.3,2.0) –Sunburn: RR = 2.0 (1.7, 2.4) Slightly stronger for childhood vs. adult burns “Chronic” exposure (more continuous pattern): –Outdoor work: RR = 0.95 (0.9, 1.0) Source: Gandini et al. Eur J Cancer 2005
Intermittent exposure hypothesis Pattern and amount of exposure important Risk increased by either: increased total amount of exposure for a fixed degree of intermittency or increased degree of intermittency for a fixed amount of exposure
Intense sun exposure in youth may be especially harmful Melanoma occurs at relatively young ages Young age at migration to Australia increases risk Most nevi (moles) arise prior to age 20 –nevi are related to sun exposure –many nevi increases the risk of melanoma Melanoma body site distribution in young adults favours sites not usually exposed (trunk & limbs vs. head & neck) Some epidemiologic studies show stronger associations with early age at exposure - not consistent or convincing One study