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*

0 5000 10000 15000 20000 25000 30000 35000

Non-HodgkinLymphoma

Colorectum

Lung

Breast

Prostate

Skin

Estimated number of new cases, 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

0

2

4

6

8

10

12

14

16

18

1972 1977 1982 1987 1992 1997 2002Year of diagnosis/death

Age-s

tand

ardi

zed r

ate p

er10

0,000

Male incidence Female incidenceMale mortality Female mortality

Source: Cancer Care Ontario (Ontario Cancer Registry, 2007).*3-year moving averages standardized to the Canadian 1991 population.

0

10

20

30

40

50

60

70

80

1972 1977 1982 1987 1992 1997 2002

Year of diagnosis

Age-s

tanda

rdize

d rate

per 1

00,00

0

15-34 55-74

35-54 75+

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

0

10

20

30

40

50

60

70

80

1972 1977 1982 1987 1992 1997 2002

Year of diagnosis

Age-s

tanda

rdize

d rate

per 1

00,00

0

15-34 55-74

35-54 75+

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

0

5

10

15

20

25

1972 1977 1982 1987 1992 1997 2002

Year of diagnosis

Age-s

tanda

rdize

d rate

per 1

00,00

0

Males 15-34 Females 15-34

Males 35-54 Females 35-54

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

0

5

10

15

1972 1977 1982 1987 1992 1997 2002

Year of diagnosis

Age-s

tanda

rdize

d rate

per 1

00,00

0

Males 15-24 Females 15-24

Males 25-34 Females 25-34

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

Thyroid19%

Testis10%

Melanoma10%

Hodgkin lymphoma

9%

Breast8%

Non-Hodgkin lymphoma

7%

Cervix uteri5%

Leukemia 5%

Brain5%

Other22%

Source: Cancer Care Ontario (Ontario Cancer Registry, 2007) Cases diagnosed at ages 15-34 in 2002-2004.

(N=504)

Use of tanning equipment

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.

0 20 40 60 80 100

Pre-vacation tan

Prolong tan

Special occasion

To look better

Build a base tan

% of users

Boys

Girls

Beliefs about tanning, tanning equipment users vs. non-users, Ontario teens

0 10 20 30 40 50 60 70 80 90 100

Bed use not at all harmful

Bed less skin aging thansun

Bed less risky than sun

Feel pampered at salon

Tan looks healthy

Tan looks more attractive

Leather skin from longterm tanning

Can be too tanned

% agree/strongly agree

Non-user

User

Source: Youthography Inc. poll commissioned by Canadian Cancer Society, Ontario Division, October 2006.

Use of tanning equipment in Ontario: Young adults

0

20

40

60

80

100

Per

cent

of O

ntar

ians

in re

leva

nt

age

grou

p

Unprotected time in sun

Adults (18+)

Tanning equipmentYoung adults (18-34)

SunburnsAdults (18+)

Cancer 2020 target Male, reporting PHUs Female, 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

Tanning equipment and skin cancer

• Meta-analysis #11 (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 #22 (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 #21 (3 studies to March 2006)

– Ever vs. never use: RR = 2.25 (95% CI: 1.08-4.70)– 1 study2 found odds ratio increased by 20% for each decade younger at first

use

Basal cell carcinoma• Meta-analysis #21 (4 studies to March 2006)

– Ever vs. never use: RR = 1.03 (0.56-1.90)– 1 study2 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

0

5

10

15

20

25

30

35

40

1972 1977 1982 1987 1992 1997 2002

Year of diagnosis

Age-s

tand

ardi

zed

rate

per 1

00,00

0

15-34 55-74

35-54 75+

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