world cancer report - iarc

eing based on (i) time trends in the incidence
of, or mortality due to, cervical cancer
in relation to screening intensity; (ii)
risk of cervical cancer in individuals in
relation to their screening history [1,4].
Nationwide programmes were established
in Finland, Iceland and Sweden; in
Denmark, programmes covered only 40%
of the female population and in Norway
only 5% [5]. In Iceland, cervical cancer
mortality fell by 80% between 1965 and
100
50
25
10
5
2.5
Time since last negative Relative protection 95% confidence
smear (months) (no. of cases in brackets) interval
1
Denmark
1960 19701980 1990 2000
0-11 15.3 (25) 10.0-22.6
12-23 11.9 (23) 7.5-18.3
24-35 8.0 (25) 5.2-11.8
36-47 5.3 (30) 3.6-7.6
48-59 2.8 (30) 1.9-4.0
60-71 3.6 (16) 2.1-5.8
72-119 1.6 (6) 0.6-3.5
120+ 0.8 (7) 0.3-1.6
Never screened 1.0
Table 4.18 Screening offers protection against cervical cancer: combined analyses of cohort and casecontrol
studies suggest that the shorter the time since the last negative smear result, the greater the protection
a woman has against invasive cervical cancer.
100
50
25
10
168 Prevention and screening
5
2.5
1
1982, compared with 50% in Finland, 34%
in Sweden, 25% in Denmark and 10% in
Norway. More recently, the effect of cytologic
screening on the incidence of cervical
cancer has been examined in 17 populations
covered by cancer registries
between the early 1960s and late 1980s
[6]. Compared with the time before the
introduction of screening, the age standardized
incidence rates decreased by at
least 25% in 11 of the 17 populations, with
Australia Hong Kong USA Poland
Fig. 4.45 Trends in mortality from cervical cancer. D.M. Parkin et al. (2001) Eur J Cancer 37, suppl. 8: S4-66.
100
50
25
10
5
2.5
1
100
50
25
10
5
2.5
1
the largest effect occurring in the 45-55
year age groups. The reduced efficacy of
screening in older women is attributable
to a lower screening coverage and possibly
by lower test sensitivity. Where evident,
apparently reduced efficacy in
younger women may be the result of
transfer of cases to younger ages, as a
result of earlier detection in the women’s
lifetime due to cytological screening. This
phenomenon in turn may obscure ineffec-
1960 19701980 1990 2000 1960 19701980 1990 2000 1960 19701980 1990 2000 1960 19701980 1990 2000 1960 19701980 1990 2000
Black
White
Fig. 4.44 Papanicolaou-stained cervical smear
preparation showing a cluster of abnormal cells.
100
50
25
10
5
2.5
1
100
50
25
10
5
2.5
1
Cuba