hazards of smoking and benefits of cessation

1. Hazards of smoking and
benefits of stopping:
UK and worldwide
Richard Peto, University of Oxford
• Many young men started smoking in the first few decades
of the 20th century, so full lifelong risks are now known.
• Young women started smoking around mid-century, so
hazards in later middle age only just became apparent

2. Richard Doll: mortality and smoking in
male British doctors born 1900-30
34,000 men recruited in 1951 & followed up to 2001
– Moderate hazard for smokers born 1851-1899, as they did
not smoke substantial numbers of cigarettes when young
– Bigger hazard for smokers born 1900-1930:
about HALF eventually killed by tobacco
– Those who stopped before age 40 (preferably well before 40)
avoided nearly all the excess risk in later middle age

5. THE UK MILLION WOMEN STUDY
Valerie Beral, Kirstin Pirie, Richard Peto, unpublished
First large prospective study of women who
have smoked throughout adult life
Big risks, even though UK cigarette yields have
been lowered in recent decades

6. THE UK MILLION WOMEN STUDY
‘
3.4 Current vs never-smoker,
all-cause mortality ratio*
2.6
1.8
*Fully standardised mortality ratio,
by smoking habit at start of 12-year FU

7. THE MILLION WOMEN STUDY
All-cause mortality
Ex-smokers and current smokers
3.1
2.1
1.7
1.2
1.06

8. THE MILLION WOMEN STUDY
Stopped at Current
age 35-44 smokers
Age at starting 18.8 19.0
Cigarettes per day
14.7 15.3
while smoking

9. THE MILLION WOMEN STUDY
Lung cancer mortality
Ex-smokers and current smokers
24.6
13.0
6.4
3.5
1.5 1.8

10. THE MILLION WOMEN STUDY
All vascular mortality
Ex-smokers and current smokers
3.7
2.0
1.8
1.2
1.0

11. Hospital admission
with any mention of
disease/procedure
Current versus
never-smoker

12. Illustration of the effects of a 3-fold difference in
annual death rates on mortality at ages 35-79 *
78%
47%
* Taking death rates in smokers to be twice the UK 2009 death rates, and
death rates in non-smokers to be two-thirds of these national death rates

14. Nationwide delay between increase in
smoking by young adults
& main increase in tobacco deaths
when they reach middle & old age
eg, USA 1900-2000

16. Chinese cigarette increase
40 years after US increase
Delayed hazard: observed (1950, 1990)
and predicted (2030) proportions of all
deaths at ages 35-69 due to tobacco
US (all adults) China (men)
1950 12% 1990 12%
1990 33% 2030 33%

17. Product of domestic cigarettes in China
Billion
0
0 2000 billion
0
0 1000 billion
0
0
1949 1954 1959 1964 1969 1974 1979 1984 1989 1994 1999 2004

18. INDIA: 1 million tobacco deaths
per year during the 2010s
Jha et al, NEJM 2008

19. World tobacco deaths,
if current smoking patterns continue
2000-2025 ~150M
2025-2050 ~300M
2050-2100 >500M
TOTAL for the ~1000M
21st century (1 billion)
Compare with ~100M
20th century total (0.1 billion)

20. Prevention of a substantial proportion of the
450 million tobacco deaths before 2050
requires adult cessation
Continuing to reduce the % children starting
smoking prevents many deaths,
but its main effect will be on mortality in
~2050 & later

21. Worldwide, HIV, TOBACCO, ALCOHOL
& OBESITY
are the only big causes of death that have
increased substantially since 1990 in
some large populations.
Death in old age is inevitable,
but death before old age is not