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