Download Estimation and projections of colorectal cancer trends in Italy.

International Journal of Epidemiology
© International Epidemiological Association 1997
Vol. 26, No. 5
Printed in Great Britain
Estimation and Projections of
Colorectal Cancer Trends in Italy
RICCARDO CAPOCACCIA,* ROBERTA DE ANGELIS,* LUISA FROVA,** GEMMA GATTA,† MILENA SANT,†
ANDREA MICHELI,† FRANCO BERRINO,† ETTORE CONTI,‡ LORENZO GAFÀ,§ LUCA RONCUCCI|| AND
ARDUINO VERDECCHIA*
Capocaccia R (Laboratory of Epidemiology and Biostatistics, Istituto Superiore di Sanità, viale Regina Elena 299, 00161
Rome, Italy), de Angelis R, Frova L, Gatta G, Sant M, Micheli A, Berrino F, Conti E, Gafà L, Roncucci L and Verdecchia A.
Estimation and projections of colorectal cancer trends in Italy. International Journal of Epidemiology 1997; 26: 924–932.
Background. Occurrence of and prognosis for tumours of the colon and rectum are thought to be changing rapidly due
to simultaneous changes in risk factor prevalence, early diagnosis and treatment. In this paper time trends of morbidity,
survival and mortality for colorectal cancer during the period 1970–1990 are estimated and analysed.
Methods. Mortality trends were obtained from official death certificates. Relative survival rates were computed from
population-based cancer registries. Incidence and prevalence rates were estimated from mortality and survival data.
Results. Incidence rates were increasing during the period considered, with a lower rate of increase for the youngest birth
cohorts. Relative survival rates of both colon and rectum cancers were higher for women, and for younger age groups,
and were positively associated with period of diagnosis. No significant survival difference among the cancer registries
used was found. A total of about 155 000 prevalent cases, 40% of which had been diagnosed >7 years before, were
estimated in the Italian population for the year 1990. Mortality rates were slightly increasing for men and stable for women.
Projections of colorectal cancer trends to the year 2000 indicate major expected rises in both incidence and prevalence.
Conclusion. Colorectal cancer represents a problem of growing impact for health services in Italy. This conclusion can
probably be extended to many developed countries.
Keywords: colorectal cancer, occurrence, survival, time trends, Italy
the diffusion of effective adjuvant therapies. Recent
data show,1 for many countries, diverging time trends
between incidence and mortality, with mortality rates
remaining almost steady, or even decreasing, despite
an increasing trend in incidence rates. A recent large
collaborative survival study of data from 30 populationbased cancer registries in 12 European countries,3
showed an increasing proportion of long-term survivors
of colon and rectum cancer. Finally, colorectal cancer
prevalence is expected to become a major health problem as a result of high and increasing incidence and
survival rates.
Italy presents all the features of the dynamics described
above with, especially in the Northern regions, socioeconomic conditions and cultural attitudes similar to most
Western European countries. A marked geographical
North-South gradient of colorectal mortality was evident in Italy,4 with two- to three-fold higher mortality in
the Northern regions. Reduction of these geographical
differences is expected, as a consequence of the progressive homogenization of Italian dietary habits.2
For these reasons Italy provides a good location for
the study of colorectal cancer occurrence. From an
aetiological point of view, this enables the consistency
between colorectal cancer trends and the changing
The epidemiology of colorectal cancer is expected to
undergo significant changes as a consequence of an
evolving pattern of possible risk factors and of continuing improvement in diagnostic and therapeutic
activities. These phenomena could substantially
modify, directly and through their mutual links, levels
and trends of incidence, survival, mortality and prevalence. Colorectal cancer risk, which has been increasing
for several generations and is still increasing in
populations with low incidence,1 is likely to have been
influenced by the dramatic dietary changes over this
century and by the progressive diffusion of industrial
alimentary products and the subsequent homogenization of dietary habits.2 Moreover, incidence will be
significantly modified if the frequency of early
diagnosis grows substantially in the near future.
Survival is improving as a result of an increase in
early diagnosis, advances in surgical technology and
* Laboratory of Epidemiology and Biostatistics, Istituto Superiore di
Sanità, viale Regina Elena 299, 00161 Rome, Italy.
** National Institute of Statistics, Rome, Italy.
†
Division of Epidemiology, National Cancer Institute, Milan, Italy.
‡
Latina Cancer Registry, Latina, Italy.
§
Ragusa Cancer Registry, Ragusa, Italy.
||
Colorectal Cancer Registry, Modena, Italy.
924
COLORECTAL CANCER TRENDS IN ITALY
pattern of its possible determinants to be checked. On
the other hand, it gives a reference frame to compare,
interpret and evaluate the future trends of the disease.
In this paper we present and analyse the observed
mortality and survival data and the estimated incidence
and prevalence rates for colorectal cancers in Italy
during the period 1970–1990. On the basis of past
trends, incidence and prevalence projections to the year
2000 are also given.
MATERIALS AND METHODS
Survival data were collected from all incident cases
observed in four Italian provinces covered by cancer
registration. The Lombardy cancer registry contributed
2393 incident cases diagnosed in the province of Varese
(Northern Italy) during the period 1978–1984. The
cancer registries of Modena (period of diagnosis 1985)
and Latina (1983–1984), provinces in central Italy, contributed 132 and 189 cases, respectively. Finally, 303
incident cases from the southern province of Ragusa
(1981–1984) were included. Twenty-three cases were
lost to follow-up. The remaining 2994 cases (1868 colon
cancers and 1126 rectum cancers) were followed until
December 1991, thus ensuring a minimum potential
follow-up of 5 years.
Official mortality data for the period 1970–1990
were obtained from the National Institute of Statistics
(ISTAT) as individual records. Death codes 153 (colon)
and 154 (rectum) were selected for the period 1970–
1979 (ICD 8th revision), while codes 153, 154 and 159.0
(intestine NOS) were considered for the period
1980–1990 (ICD 9th revision). Population size by age,
sex and geographical area was estimated from census
data and from inter-census births, deaths and migration
numbers.5 It is well known1 that separate analysis of
mortality data for colon and rectum cancers is made
difficult by major misclassification problems in defining and coding the cause of death. As usual in descriptive epidemiological works, the two cancer sites
will therefore be analysed jointly.
This paper is based on methods for statistical
analysis of relative survival rates, for the estimation of
incidence and prevalence, and for trend projections, applied in a previous6 work on stomach cancer. Relative
survival was computed by the method of Hakulinen
et al.7–9 The method of Estève et al.10 was used for
multiple regression analysis. In both cases, observed
survival rates were corrected for age-, area-, sex- and
period-specific general mortality levels. Further details
are reported in a previous paper.11
The estimation of incidence and prevalence from
mortality and survival data was carried out by the
925
method of Verdecchia et al.12 which has been applied in
previous studies.13,14 It assumes incidence to be a continuous function of independent factors such as age,
year of diagnosis (period) and year of birth (cohort).
The equations relating incidence, survival and mortality
rates were used as a link function between incidence
and mortality in a non-linear regression model for
maximum likelihood estimation of the parameters of
the incidence function. These parameters were determined as those giving the best fit of the mortality rates
observed during the period 1970–1990, on the basis
of the given survival rates. Prevalence, defined as the
proportion of all people with previous colorectal cancer
diagnosis in the general population, was then derived
from the estimated incidence function and the observed
survival rates. For method validation purposes, estimates
of colorectal cancer incidence in Italian provinces with
cancer registration were compared to the corresponding
data observed by the local registries. A total of 3008
male cases and 2640 female cases were estimated in the
four cancer registries. The corresponding numbers
observed by the registries were 3004 and 2605, respectively. Period-specific comparisons were possible for
the Lombardy cancer registry, which observed 487 new
cases during 1976–1978, 1011 cases during 1978–1982,
and 1352 cases during 1983–1987. The corresponding
estimates were 481, 993 and 1318 cases, respectively.
These results, reported in more detail elsewhere,15 indicated a good agreement between estimated and observed
data.
Projections of incidence rates for the period 1991–
2000 were calculated on the basis of the incidence
function obtained for the estimation period 1970–1990.
For this purpose, both age- and cohort-estimated effects
were also assumed to hold during the projection period.
Furthermore, no incidence changes simultaneously
affecting all ages were considered. Regarding the
pattern of survival, we adopted a scenario approach by
assuming: A) survival continuing to increase at the
same rate as observed during the period 1978–1985 or
B) survival remaining constant at the rates estimated in
1990. Future prevalence and mortality rates were
derived from projected trends of both incidence and
survival functions.
Birth cohort-specific expected 0–84 years cumulative
risks were used to represent colorectal cancer cohort
effects. This indicator is calculated1,16 as the sum of agespecific incidence rates estimated (at ages ,1991
minus year of birth) or projected (at ages .1990 minus
year of birth) for each birth cohort. It estimates approximately the probability of developing the disease before
age 85 for people belonging to a given birth cohort and
in the absence of competitive mortality. Estimates of
926
INTERNATIONAL JOURNAL OF EPIDEMIOLOGY
FIGURE 1 Estimated cumulative risk of colorectal cancer incidence in male birth cohorts from North, Centre and South of Italy
FIGURE 2 Estimated cumulative risk of colorectal cancer incidence in female birth cohorts from North, Centre and South of Italy
cumulative risks for birth cohorts born before 1895
and after 1940 should be considered with caution. The
former are derived from under 10 years of observed
mortality data, while the latter are based on the relatively low mortality rates observed for people under 50.
Cross-sectional 0–84 years cumulative rates were
also calculated, according to the definition given by
standard cancer registries publications, summing up the
estimated age-specific incidence rates obtained by the
model for a fixed time period.
While the estimation method works in reverse, from
mortality to incidence and prevalence, the results are
better analysed in the opposite sense, i.e. from determinants (incidence and survival) to effects (prevalence
and mortality). They will therefore be presented and
discussed accordingly.
Cross sectional 0–84 cumulative rates, estimated for
the whole country in the year 1990, were 9.3 and 6.3 for
males and females respectively.
Table 1 reports the national age-adjusted estimated
and projected incidence rates of colorectal cancer at the
national level, according to sex, decade and age group,
with the corresponding absolute number of cases for all
ages. The increase in incidence is evident in both sexes
and in all ages for the period 1970–1990. However, a
deceleration of the increase between the first and the
second decade is estimated for the 25–49 age group.
A decrease of incidence is obtained, for the same age
group, during the projection period 1991–2000. Ageadjusted rates are scarcely influenced by the youngest
cohorts, and steeply increase during both the estimation
and the projection periods. The ratio between male and
females age-adjusted rates increases from 1.28 in 1970
to 1.52 in the year 2000. The estimated absolute number
of cases rises from 16 000 (49% men, 51% women)
for the year 1970, to nearly 50 000 for the year 2000
(53% men, 47% women). We estimated by age
standardization that about one half of this growth can
be attributed to the higher incidence levels, while the
other half was due to the increasing size of the elderly
population.
RESULTS
Incidence
Trends of expected 0–84 cumulative risk by birth cohort and geographical area are represented in Figures 1
and 2, for men and women respectively. The probability
of having colorectal cancer for people born in 1890 was
about 4–5% in the North and Centre and 2% in the
South of the country, with a sex ratio very near to one.
The cumulative risk increased steeply for subsequent
generations. Male cohorts born in 1940 present an
expected risk of 18% for the Centre, 16% for the North
and 13% for the South. In women, it was about 10%
in all areas. A deceleration of the increasing trend is
evident however for the most recent cohorts. A plateau
is apparently reached for people born around 1950,
whose cumulative risks by geographical area vary in
men, but are quite homogeneous in women.
Survival
The excess mortality rate of colorectal cancer patients
was analysed according to sex, age group, period of
diagnosis, registry and subsite. Figure 3 presents the overall survival curves by subsite. Colon cancer patients
had lower survival rates (60% versus 68%) during the
first year since diagnosis, afterwards their survival
curve quickly tends to level off. Rectum cancer, on the
contrary, carried higher mortality from one up to 5 years
927
COLORECTAL CANCER TRENDS IN ITALY
TABLE 1 World population age-standardized incidence rates and absolute number of new cases, estimated and projected for colorectal
cancer in Italy (rates are per 100 000, no. of cases rounded to 100)
Age group
25–49
50–69
70–84
25–84
All ages
No. of cases
Men
Women
1970
1980
1990
2000
1970
1980
1990
2000
7.9
70
220
42
23
7800
9.4
86
275
51
29
11 000
11
122
387
71
40
18 600
10
156
517
90
50
26 000
7.7
54
169
33
18
8100
9.5
66
206
40
22
11 700
11
83
252
49
28
18 300
10
100
314
59
33
23 500
FIGURE 3 Relative survival rates of colon and rectum cancer
patients in Italy. 2994 incident cases diagnosed by four Italian
cancer registries during the period 1978–1984
since diagnosis. The two curves cross-over at 2 years
from diagnosis and are parallel after 5 years.
Table 2 reports 5-year observed and relative survival
rates, according to site, sex and age group. Colon cancer patients presented higher survival with respect to
those with rectum cancer, in both sexes and in all ages.
Furthermore, better prognosis was observed for women
than for men, and for the youngest versus the oldest age
groups.
Because of the clear non-proportionality of mortality
risks between colon and rectum cancer patients, multiple
regression analysis was separately performed for the
two subsites. The results are shown in Table 3, which
presents the relative risks associated with the factors
considered and the corresponding confidence limits.
After allowing for the different shapes of the baseline
survival curves, colon and rectum cancer present relative risk patterns very similar to each other. No clear
geographical pattern was found: relative survival rates
for the other registries did not differ significantly from
the ones estimated for Varese. However, the factor
‘area’ was not removed from the regression model to
avoid possible bias due to different subsite distribution
or to different incidence periods covered by the various
registries. Survival rates were higher for women than
for men, but the significance of sex coefficient was
borderline. Survival decreased with age increasing,
with relative risks particularly high for the oldest age
group (about 2 for the middle age group). Survival
increased over time: the relative risk associated with a
diagnosis made in 1984–1985 compared to 1978–1979
was 0.76 for colon and 0.72 for rectum. The solid line
in Figure 4 shows the overall relative survival curve
jointly estimated for colorectal cancer in 1980–1981.
The procedure for estimating incidence and prevalence of colorectal cancer required that survival data
refer to exactly the same nosological grouping. In fact,
survival rates of colorectal cancer at the national level
depend on the relative proportion of the two sites,
which present slightly different survival levels. The
variability of the proportion of colon cancer over all
colorectal cancer deaths across Italian regions ranges
between 54% and 72%, considering17 the lowest and
the highest sex- and area-specific values. The survival
curves obtained under these two extreme alternatives,
(Figure 4), are very close to each other. We concluded
that the sensitivity of survival values to the assumed
mixing proportion is only slight. This problem was
therefore ignored in the estimation procedure, and the
same family of age-, period- and sex-specific survival
curves was assumed for colorectal cancer patients in the
Italian population.
928
INTERNATIONAL JOURNAL OF EPIDEMIOLOGY
TABLE 2 Observed 5-year survival rates and corresponding standard errors for 2994 colon and rectum cancer patients in Italy, by sex and
age group
Age
Colon
Rectum
No.
OBSa
SEb
RELc
SE
No.
OBS
SE
REL
SE
Men
0–49
50–59
60–69
70–79
80+
All
73
172
231
313
107
896
52.1
42.3
32.9
24.3
10.1
31.3
5.8
3.8
3.1
2.4
2.9
1.6
53.6
50.1
38.5
34.9
24.5
40.7
6.0
4.1
3.6
3.5
7.2
2.0
50
123
159
221
70
623
46.0
43.1
27.0
17.2
8.6
26.2
7.1
4.5
3.5
2.6
3.4
1.8
47.3
46.5
31.5
24.8
20.4
33.8
7.2
4.8
4.1
3.7
8.0
2.8
Women
0–49
50–59
60–69
70–79
80+
All
94
133
225
328
192
972
50.0
43.6
41.8
35.5
19.8
36.4
5.2
4.3
3.3
2.7
2.9
1.5
50.0
44.7
44.4
42.8
39.2
44.0
5.2
4.4
3.5
3.2
5.7
1.8
48
79
125
177
74
503
40.0
41.7
35.2
27.6
9.5
30.2
7.1
5.6
4.3
3.4
3.4
2.0
39.9
42.7
37.4
33.2
18.7
35.6
7.1
5.7
4.5
4.0
6.7
2.4
a
OBS = observed survival rate.
SE = standard error.
c
REL = relative survival rate.
b
TABLE 3 Relative risks, (RR) and 95% confidence intervals (CI),
of excess hazard rates for colon and rectum cancer patients in
Italy
Factor
Colon
Rectum
RR
95% CI
RR
95% CI
Sex
Males
Females
1
0.85
0.74–0.96
1
0.88
0.75–1.03
Age
0–49
50–59
60–69
70–79
80+
0.77
0.81
1
1.17
1.96
Period
1978–1979
1980–1981
1982–1983
1984–1985
Registry
Varese
Modena
Latina
Ragusa
0.60–1.00
0.66–1.00
0.99–1.38
1.60–2.38
0.72
0.74
1
1.15
1.93
0.52–0.97
0.58–0.94
0.94–1.41
1.48–2.51
1
0.93
0.73
0.76
0.78–1.12
0.61–0.88
0.61–0.94
1
0.93
0.83
0.72
0.74–1.15
0.66–1.04
0.55–0.93
1
1.00
1.27
1.15
0.69–1.45
0.98–1.64
0.93–1.42
1
0.62
0.89
1.10
0.38–1.01
0.61–1.28
0.84–1.44
Prevalence
Estimated prevalence is presented by sex and age group
in Table 4. In 1990, men and women belonging to the
youngest age group present similar levels. Estimated
prevalence steeply increases with age, with levels about
20% higher in men than in women, for both the middle
and the old age group.
Table 4 also reports the absolute number of prevalent
cases estimated in 1990 and stratified according to time
since diagnosis. The first group considers patients
(29% of total cases) diagnosed during the current or
preceding year, which are likely to be still in treatment
for their disease. About 40% of these patients are expected subsequently to die from colorectal cancer. The
second group concerns patients diagnosed 2–6 years
before (32% of total cases) who are still at risk of disease recurrence (estimated about 10%), and who present
mortality levels higher than the general population. The
third group considers cases whose life expectancy is
similar to that of the general population,18 and therefore
can be considered as cured (40% of total cases). The
overall proportion of long-term survivors increases
with age: 31% for the age group 25–49 years, 37% for
50–69 and 42% for those aged 70–84 years.
Projected levels for the year 2000 were calculated
assuming either that survival will continue to increase
at the currently estimated rate (Scenario A), or that it
929
COLORECTAL CANCER TRENDS IN ITALY
FIGURE 4 Overall relative survival rates of colorectal cancer patients, according to the assumed proportion of colon cases. Solid
line: observed proportion (62%); dotted and dashed lines:
minimum (54%) and maximum (72%) proportion, respectively
will remain constant at 1990 levels (Scenario B). As the
behaviour of incidence is considered to be the same,
projected prevalence will be higher under the first assumption. During the projection period, the prevalence
is expected to remain nearly constant in the young, and
to rise in the other age groups. The number of cases
almost doubles in 10 years, particularly under Scenario
A. Different assumptions on survival trends have a
minor influence on 10-year projections of prevalent
cases, which are mostly determined by the rise in
incidence and by population ageing.
Mortality
Observed and projected trends in colorectal cancer
mortality are presented by sex and age group in
Table 5. The general pattern is quite similar between
the two sexes. Due to the combined trends of incidence
and survival, mortality rates appear slightly increasing
during 1970–1980, and slightly decreasing or stable
during the subsequent decade.
The direction of projected mortality trends for the
period 1991–2000 depends on the assumption of future
behaviour of survival rates. Increasing survival, as
considered in Scenario A, will lead to a future drop in
mortality rates in both sexes and in all age groups. On
the contrary, survival stable at the late 1980s levels
(Scenario B) will be associated with future increases
in mortality rates for ages >50 years and in agestandardized rates. A decrease in mortality, because of
the estimated declining cohort effects of incidence, will
only be observed for the youngest age group.
DISCUSSION
National incidence and prevalence trends presented
above were estimated by assuming that survival
rates, derived by sex, age and year of diagnosis from
four Italian cancer registries, were valid for the whole
population. Although the registries used operate in
regions with different socio-economic levels, the
Italian public national health service, established in
the 1970s, in principle provides fairly uniform availability of health facilities nationwide. However,
TABLE 4 World population age-standardized prevalence and absolute number of prevalent cases, estimated and projected for colorectal
cancer in Italy (rates are per 100 000, no. of cases rounded to 100). Projection Scenarios: A, survival increasing; B, survival constant
Sex/age
group
1990
2000
Cases by disease duration
Rate
Scenario A
Scenario B
All
0–1
2–6
.6
Rate
Cases
Rate
Cases
Men
25–49
50–69
70–84
25–84
All ages
47
473
1462
276
152
4600
30 900
30 300
65 800
71 200
1700
10 000
8800
20 500
21 800
1600
11 000
10 000
22 600
24 300
1300
9900
11 500
22 700
25 100
51
777
2582
449
250
5000
53 000
65 000
123 000
137 000
48
717
2345
412
229
5000
49 000
58 000
112 000
125 000
Women
25–49
50–69
70–84
25–84
All ages
46
407
1163
234
131
4500
30 500
37 500
72 500
84 200
1500
8500
9800
19 800
22 500
1500
9300
10 700
21 500
24 700
1500
12 700
17 000
31 200
37 000
53
612
1841
348
181
6000
46 000
69 000
121 000
138 000
50
575
1705
325
169
5000
43 000
64 000
112 000
128 000
930
INTERNATIONAL JOURNAL OF EPIDEMIOLOGY
TABLE 5 World population age-standardized mortality and absolute number of deaths, observed and projected for colorectal cancer in
Italy (rates are per 100 000, number of cases are rounded to 100). Projection scenarios: A, survival increasing; B, survival constant
Age
group
Men
1970
1980
Women
2000
1990
A
25–49
50–69
70–84
25–84
All ages
No. of cases
4.6
44
165
28
15
5300
4.1
51
190
31
18
7000
4.1
52
200
32
18
9000
1970
2000
1990
B
2.3
3.5
44
64
188
268
28
40
16
24
9500 13 500
endoscopy departments were established later and are
less frequent in the South than in the North. The slight
survival differences between areas therefore can be
related to different distribution of disease stages, even
if there was no organized screening during the study
period.
The definition of stage categories is not uniform in
time and between areas, and depends on the thoroughness of diagnostic investigations. This phenomenon is
well known as the ‘stage migration effect’.3 Tumour
stage, broadly classified as localized, regional and
distant spread, was available in our study for about 40%
of patients only. The percentage of localized and distant
spread cancers decreased, over the study period, from
38% and 31% in 1978–1979 to 25% and 22% in
1984–1985, respectively. Meanwhile, the percentage of
regional spread cancers increased from 31% to 53%.
This pattern can be due to a mixture, with unknown
weights, of both early diagnosis and stage migration
effects. For these reasons, stage was not analysed as a
prognostic factor in this study.
Survival rates reported by Italian cancer registries are
similar for colon cancer, and slightly lower for rectum
cancer, compared to those estimated for the European
population.3 The prognostic role of age and decade
of diagnosis is also consistent with findings from the
European study,3 as well as the different shapes of
survival curves between colon and rectum according to
time since diagnosis. This last phenomenon could be
explained by earlier symptoms and easier diagnosis for
cancer sites which are more accessible, such as the
rectum. Consistency with survival data from other
European countries strengthen the assumption that age
and time trends of the survival rates used in the model
give a reliable basis for estimation.3
1980
A
3.7
32
115
20
11
5100
4.1
34
130
22
13
7000
3.7
33
124
21
12
8800
B
2.0
3.0
25
37
103
148
16
24
10
14
7500 10 800
The aetiology of colon and rectum cancers has yet
to be well-ascertained. However, strong indications of
close relationships with dietary factors come from both
analytical and descriptive epidemiological studies.19
Colorectal cancers appear to be positively associated
with consumption of saturated fats and animal proteins,
and negatively associated with intake of vegetables
and fruits. Data from population surveys on food
consumption2 revealed major differences among Italian
regions, with a typical Mediterranean diet in Southern
communities, and a higher risk dietary pattern in
Northern communities. These differences, that were
striking until the 1950s, appeared to have decreased in
recent decades. In the 1980s, Italian dietary habits appeared to be more homogeneous, and to be approaching
the high risk pattern of Northern European countries.
These observations are consistent with the incidence
trends of the disease estimated above, showing an increase of cumulative risk by birth cohort particularly
marked for the Southern regions.
The different incidence for males and females
suggests an aetiologic role for sex-related factors. Some
studies found that reproductive factors, such as nulliparity, advanced age at first and last delivery, might be
associated with a higher risk of colorectal cancer. The
interaction between sex hormone metabolism and
nutrition may also play an aetiologic role.20
A fairly constant mortality trend was found in Italy
despite increasing incidence rates. This is a direct
consequence of increasing survival over time. Coleman
et al.1 showed similar patterns of incidence and mortality in other European population-based cancer registries.
Projected incidence and mortality rates have been
obtained based on the assumption that age and cohort
effects estimated for 1970–1990 will continue to be valid
COLORECTAL CANCER TRENDS IN ITALY
for the projection period 1991–2000. Possible changes
in true colorectal cancer risk, associated for instance
with changing dietary patterns, are likely to occur
gradually over time, and therefore should already be
captured by the estimated trends of cohort effects. It is
unlikely that risk of colorectal cancer due to other
factors will change so suddenly as to affect incidence
rates simultaneously and in a substantial way for all age
groups during the projection decade. On the other hand,
early diagnosis could affect measured incidence rates,
including a higher frequency of localized cancers and
could also improve survival. Increasing survival could
also be expected if adjuvant therapies21 prove to be effective. During the projection period, survival has been
assumed either to increase by 4% per year (Scenario A),
or to remain constant (Scenario B). The estimates
derived under Scenario B are in accordance with previously published projections,22 which are based only on
observed mortality trends, and do not take into account
possible future increases in survival.
Projections of colorectal cancer trends can be better
appreciated if compared to the corresponding estimates
obtained for stomach cancer, 6 which in Italy still represents the second most common site of cancer death. The
absolute number of incident cases of stomach cancer
is expected to decrease from about 18 000 to 16 000
during the period 1990–2000, in contrast with the
forecasted rise (from 37 000 to 50 000) of cancers of
the colon and rectum. The differences in expected trends
of prevalence appear even more striking. The number
of patients with previous diagnosis of gastric cancer
should increase during the present decade from 104 000
to 110 000, under the hypothesis of increasing survival
rates. Meanwhile, the number of prevalent cases of
colorectal cancer is expected almost to double: from
about 150 000 cases in the year 1990 to at least 250 000
cases (assuming constant survival) or to a maximum of
275 000 cases (assuming increasing survival) in the
year 2000. Particular intensive care and follow-up protocols should be given to the 30% of patients diagnosed
<2 years before, due to the higher risk of local recurrences.21,23 However all patients remain at high risk for
a second colorectal cancer.23 The figures presented in
this paper may be useful for estimating the need for
periodical endoscopic examinations of all prevalent
cases throughout the rest of their lives, as routinely
recommended.
For all these reasons, the potential impact of future
trends of colorectal cancer prevalence on the national
health service is bound to become a major one. The
same problems are expected to arise in European countries presenting demographic and epidemiological
trends similar to those reported for Italy in this paper.
931
ACKNOWLEDGEMENTS
The authors wish to thank Ms Emily Taussig for editorial revision and preparation of the manuscript.
This work was partially supported by the National
Research Council (CNR), Progetto Finalizzato ACRO
and by the European Union BIOMED Project EUROCARE.
REFERENCES
1
Coleman M P, Estève J, Damiecki P, Arslan H, Renard A.
Trends in Cancer Incidence and Mortality. Lyon: International Agency for Research on Cancer, 1993; IARC Sci
Pub. No 121.
2
Berrino F, Krogh V. I consumi alimentari in Italia in relazione
ai tumori dell’apparato digerente. In: Capocaccia R,
Verdecchia A, Terracini B (eds). Epidemiologia dei tumori
dell’apparato digerente in Italia. Ann Ist Super Sanità
1996; 4: 421–432.
3
Berrino F, Sant M, Verdecchia A, Capocaccia R, Estève J,
Hakulinen T (eds). Survival of Cancer Patients in Europe.
Lyon: International Agency for Research on Cancer, 1995;
IARC Sci Pub No.132.
4
Capocaccia R, Farchi G, Prati S et al. La mortalità in Italia
nell’anno 1990. Reports of the Istituto Superiore di Sanità,
ISTISAN 93/23, 1993.
5
Capocaccia R, Caselli G. Popolazione residente per età e sesso
nelle province italiane. Dipartimento di Scienze Demografiche dell’Università degli Studi di Roma ‘La
Sapienza’. Fonti e Strumenti 2, 1990.
6
Capocaccia R, De Angelis R, Frova L et al. Estimation and
projections of stomach cancer trends in Italy. Cancer
Causes Control 1995; 6: 339–46.
7
Hakulinen T. On long term relative survival rates. J Chron Dis
1977; 30: 431–43.
8
Hakulinen T, Tenkanen L, Abeywickrama K. Testing equality
of relative survival patterns based on aggregated data.
Biometrics 1987; 43: 313–25.
9
Hakulinen T, Abeywickrama K. A computer program package
for relative survival analysis. Comput Prog Biomed 1987;
19: 197–207.
10
Estève J, Benamou E, Croasdale M, Raymond L. Relative
survival and the estimation of net survival: elements for
further discussion. Stat Med 1990; 9: 529–38.
11
Ponz M, Micheli A, Gatta G et al. La sopravvivenza per tumori
del colon e del retto in Italia. In: Capocaccia R, Verdecchia
A, Terracini B (eds). Epidemiologia dei tumori
dell’apparato digerente in Italia. Ann Ist Super Sanità
1996; 4: 527–536.
12
Verdecchia A, Capocaccia R, Egidi V, Golini A. A method for
the estimation of chronic disease morbidity and trends
from mortality data. Stat Med 1989; 8: 201–16.
13
Capocaccia R, Verdecchia A, Micheli A, Sant M, Gatta G,
Berrino F. Breast cancer incidence and prevalence estimated from survival and mortality. Cancer Causes Control
1990; 1: 23–30.
14
Capocaccia R, Micheli A, Berrino F et al. Time trends of lung
and larynx cancers in Italy. Int J Cancer 1994; 57: 1–8.
15
De Angelis R, Frova L, Capocaccia R, Verdecchia A. Incidenza
e prevalenza dei tumori dell’apparato digerente in Italia:
stime dai dati di mortalità. In: Capocaccia R, Verdecchia A,
932
INTERNATIONAL JOURNAL OF EPIDEMIOLOGY
Terracini B (eds). Epidemiologia dei tumori dell’apparato
digerente in Italia. Ann Ist Super Sanità 1996; 4: 537–550.
16
Capocaccia R, Negri E, La Vecchia C, Decarli A. Time trends of
lung cancer in Italy. Eur J Cancer 1993; 29A: 1288–92.
17
Zanetti R, Crosignani P (eds). Cancer in Italy. Incidence data
from Cancer Registries, 1983–1987. Torino, Italy: Lega
Italiana per la lotta contro i tumori, 1992.
18
Sant M, Capocaccia R, Verdecchia A et al. Comparisons of
colon cancer survival among European countries: the
EUROCARE study. Int J Cancer 1995; 63: 43–48.
19
Tomatis L. Cancer: Causes, Occurrence and Control. Lyon:
International Agency for Research on Cancer, 1990; IARC
Sci Pub. No.100.
20
DeCosse J J, Ngoi S-S, Jacobson J S et al. Gender and colorectal
cancer. Eur J Cancer Prevention 1993; 2: 105–15.
Haller D G. An overview of adjuvant therapy for colorectal
cancer. Eur J Cancer 1995; 31A: 1255–63.
22
Negri E, La Vecchia C, Decarli A et al. Projection to the end of
the century of mortality from major cancer sites in Italy.
Tumori 1990; 76: 420–28.
23
Steele G. Follow-up plans after treatment of primary colon and
rectum cancer. World J Surg 1991; 15: 583–88.
21
(Revised version received March 1997)