Brit. J. Dis. Chest (1975) 69, 247
THE
CHANGING
PATTERN CARCINOMA
OF BRONCHIAL
J. R. BELCHER The London
Chest Hospital
and Middlesex
Hospital,
London
age incidence of bronchial carcinoma in England is changing: those dying of the disease are getting older, and this is true for both sexes. Springett (1966) inferred this and Langston (1972) observed it among his patients in the USA. This paper is concerned with the pattern of change in both sexes in the United Kingdon.
THE
Surgical
Series
Initially a study was made of the age distribution in my surgical series of 1478 patients by 5-year periods and 5-year age groups (Fig. I). This showed that the peak incidence of bronchial carcinoma among those operated on between I g5o and 1955 and between I 956 and 1960 was in the 56-60 years age group, whereas in the next decade it was in the 61-5 age group. It also showed that the proportion of patients under 50 years of age was steadily falling (from 25% in 1950-5 to 7% in rg7o-4), and that the proportion of patients operated on over the age of 65 had risen (from I 2 o/o in I 950-5 to I 7 o/o in I 970-4). Among the women there had been similar changes: a fall in the proportion under 50 from 19% to I 2% and a rise in the proportion over 65 from 6% to 32% (Fig. 2). With the increasing incidence of the disease in the whole population during these two decades, the number of patients operated on rose steadily from 214 in the 1950-5 period to 3 I 6 between 1970 and 1974. National
Figures
These changes might have been due to a change in surgical policy, for after a study published in 1965 (Belcher & Anderson 1965) there was some reluctance to operate on patients over the age of 70. This reluctance was dispelled by a subsequent publication (Bates 1g7o), and more recently the policy has been to disregard chronological age, with the result that a substantially larger proportion of patients over 70 have been operated on. At the same time, a considerable increase has occurred in the number of patients in this age group who have presented for treatment. The national figure given by the Registrar General for England and Wales have therefore been studied to seek the cause of this change, and these figures will be used from now on. (Reccivedforpublication 3unc 1975)
BELCHER
248
9 of
20-
TOW cuu In 5uq1u1 5wlU 8%
1970-74 lO-
1960-54
19xbl4d
/’
I 41145
FIG. I. The age distribution
FIG.
2. The age distribution
..l 1950-54
,
I 4ww
I
I
51155
56/w
of men with bronchial carcinoma in 3 periods of I0 years
of women with bronchial carcinoma in 3 periods of IO years
I 61165
I 66/70
I 711
in my surgical series, 1950-74,
in my surgical series, 1950-74,
THE
CHANGING
PATTERN
OF
BRONCHIAL
CARCINOMA
249
7.000Actual NUUlbW of
6.0005,000-
Registered Deaths Men
4.0003,000-
I 1950
FIG.
3. The
numbers
of men in England and carcinoma, 1950-70,
I 1955
I 1960
I 1965
Wales registered in 3 periods of
1,800
IO
I 1970
as having years
died
from
bronchial
died
from
bronchial
60-69
1,600 1,400 Actual Number
! 1,200
of 1,000 Registered Deaths
800
Wunen 600
FIG. 4. The
numbers
I
I
lg!io
1955
I
1960
I
1965
1 1970
of women in England and Wales registered as having carcinoma, x950-70, in 3 periods of 10 years
BELCHER
250
The actual numbers of persons registered as having died from bronchial carcinoma (ICD 162, 163) in three different age groups are shown in Figs 3 and 4. There was an enormous rise in the number of men over the age of 60 years dying of bronchial carcinoma between 1950 and 1970 (3722 to IO 414). A similar rise, from 638 to 1759 had occurred among the women. During the same period there had been a fall in the number of men under the age of 50 registered as dying from the disease, but a rise in the women in the same age group. Thus the surgical series reflects the national figures. Reasons
for Change
of Incidence
There are at least two possible reasons for the change of incidence: the size of the population at risk in different age groups could have changed, or the death rate of that population could have altered. In fact both have happened, but by far the most important factor was the rise in the incidence in the older age groups. Change of $opulation Figs 5 and 6 show that between I g5o and I g7o there was a substantial increase in the population in the age groups where the risk of developing bronchial TABLE
I. POPULATION
IN ENGLAND
AND WALES,
Igy-70
Age group (years)
1950 (million)
1970 (million)
Men 50-59 60-69
2’37 “73
3.01 2’37
640 000 (27%) 640 000 (37%)
Women 50-59 6o-G
2.8 2'21
3.01 2-81
210 000 (7’5%) 600 ooo (27%)
Increase
carcinoma is at its highest. Between the ages of 50 and 5g it has risen 20% in and 7.5% in women, and between 60 and 6g it has risen 37% and 27% respectively. Thus the total number of men alive in this older age group has gone up 640 ooo, and it is thus scarcely surprising that the number presenting with bronchial carcinoma in this age group has also increased (Table I). Could the increase in the number at risk have been responsible for the whole change in the incidence? The answer is ‘No’. Assuming that the death rate from lung cancer per IOO ooo of population had remained unaltered between 1950 and 1970, the number of men registered in 1970 would have been 5700, whereas in fact it was I o I I 4. Thus the rise in rate per I oo ooo in the older age group was largely responsible for the rise in numbers. men
Change in rate Between I g5o and I 970, the overall rate per I oo ooo for bronchial carcinoma rose from 4go to 1051 in men and from go-3 to 2 16 in women (Fig. 7). The
THE
CHANGING
PATTERN
OF
BRONCHIAL
CARCINOMA
251
change in rate has varied widely in different age groups and in the two sexes. Springett (1966) had already observed that a fall in the rate in younger men had been apparent since the late 1g4os, and indeed this rate is now falling up as far as the 60-64 age group (Fig. 8), though this has only happened between 1965 and 1970. Prior to this date, the rate was rising. This rise is now slowing among men, but not among women (Fig. 9). 2 million
1.5 million
1 million
1 -
_
o.5 millio” 1
45/49 50154 55/59 bOtb4 65169 70174 75/79
FIG.
5. The
changing
population represents
of men at risk between 1950 and the increase in the number alive
1970.
The
hatched
area
The
hatched
area
1 mllllon
0.5 million
c
,
,
(
(
(
(
,
45449 50/54 55159 bO/b4 65/69 70174 75/79 FIG.
6. The
changing
population indicates
of women at risk between 1950 and the increase in the number alive
1970.
The factors by which the rates have changed in these twenty years are shown in Tables 3 and 4. The older the men get, the greater the rise in the rate of the disease; on the other hand, the rate among women in all age groups has risen by a similar factor (twice). The peak rate for men now occurs between 70 and 74, while in 1950 it was between 65 and 69; in women it occurs between 75 and 26
RELCHER
252
01
FIG.
7. The
rising
incidence
’
I
1950
1955
of bronchial
I 1960
carcinoma
in inen
1950
1955
1960
of bronchial
carcinoma
I
I
1965
1970
and
women
between
I g5o and
I g7o
in s-year
age
7,000 6,0005,0004,000 3,000z,ooo-
FIG.
8. The
attack
rates
in men
1965
between
1950
1970
and
1970,
groups
79, as it did in 1950. The unique feature of bronchial carcinoma noted by Springett still holds: the rate falls after the middle seventies. The change in the rates of bronchial carcinoma in different age groups has been going on for a long time; indeed, a fall in the annual percentage rise in men has been reported as long ago as I g 14 (Gilliam et al. 1961) and Springett noted that there was no longer a rise in the 40-45 age group by 1950. A study was therefore made to see if this tendency persisted. The result is shown in Fig. I o. There has been a fall in all the percentage rises of incidence over each 5-year
THE
CHANGING
PATTERN
OF
BRONCHIAL
253
CARCINOMA
800 _ 700 -
.
65-69
600 500 400 300 200 lOO-
FIG.
g. The
attadk
rates
A I
I
I
I
1950
1955
1960
1965
of bronchial
carcinoma in women periods
40-44
1970
between
1950
and
1970,
in 5-year
70% -
60% 50% 40% 30% 206 10% -
-10
I
1950-,54
FIG.
IO. The
percentage
change
in the
I
I
,
55-59
60-64.
65-70
rates
in different 1970
age groups
of men
between
1950
and
period in each age group of men, and the rise has changed to a fall progressively earlier in the younger groups. Thus the incidence fell in 1954 for the 45-49 group, but not until rg7o for the 60-64 group; the 70-74 age group still shows a rise. The percentage rise in the total rate for the male population is also decreasing sharply, from 42% in 1950-5 to 9% in the most recent 5-year period (Fig. I I). The importance of these changes in the prediction of the future incidence of bronchial carcinoma is obvious.
BELCHER
254 TABLE
2.
CHANGE
Age grouj (years)
IN INCIDENCE BETWEEN '950
Increase
40-44
OF AND
BRONCHIAL I970
Increase
in men
x 0.85 x 0.87 None x 1.5 x 1.7 x2.4 x4.0
45-49 50-54
55-59 60-64 f-?-69 70-74
CARCINOMA
in women x 1.5 x2.1 x2.2 x2.1
x2.5 x2.0 x2.0
40%
30%
20%
10%
FIG.
I I. The
percentage
change
overall
in men
between
I g5o
and
I g7o
Changes in sex ratio It has been known for some time that the sex ratio of bronchial carcinoma has been falling in the United Kingdom. The expectation of life has been increasing in both sexes, but the increase in the population at risk has been greater in men than in women, so it might have been expected that the sex ratio would have increased. This has not happened; indeed, the reverse has been the case. The ratio for the rate has fallen from 5.4 to I in 1970 to 4-g to I in 1970, and the ratio for the total numbers from 5.1 to 4.6 to I in the same period. Table 3 shows how the ratio has changed in the various age groups and these changes are implicit in the wide differences in the change of incidence in the two sexes between 1950 and 1970. It can be seen that there is a steady rise in the ratio as age advances in 1970, whereas in 1950 the peak was reached in the 55-59 age group.
THE
CHANGING
PATTERN
OF
TABLE 3. SEX BRONCHIAL
BRONCHIAL
RATIO (M CARCINOMA
BETWEEN
CARCINOMA
:
1950
F)
OF BY
AND
DEATHS AGE
255
FROM GROUP
1970
Sex ratio
Age group (years)
‘950
40-44
4’4
45-49 50-54 55-59 60-64
7’8 7’7 :: I1 8.4 : I 8.4 : I 6.7 : I 5 : I
65-69
70-74
‘970 4:’
: I
3.g j : 5.2 : I 6.5 : I 8 : I 8.6 : I
Age under 45
45-54
55-64
65-74
75-
FIG.
I 2.
The
I
O%I projection
of Springett’s
histogram.
I The
1946
I and
1963
figures
are his
Changes of proportion of patients in various age groups The changes predicted by Springett (1966) have occurred. He showed that the proportion of patients in the 65-70 age group was rising up to 1963 and that in the younger age group (45-54 years) it was falling. This trend has continued. Fig. 12 shows the present figures added to the diagram which he drew in x966. The proportion in the younger group has fallen from 24% in 1946 to 9% in 1971, whereas the proportion in the 65-70 years age group has risen from 24% to 40% in the same period. Figure I 2 shows clearly the shift in the age incidence of bronchial carcinoma in Great Britain which led to this investigation.
BELCHER
256
Discussion The change in the age pattern of bronchial carcinoma was first noticed by Springett ( 1966) and then by Langston (1g72), although the slowing down in the rise of the death rate in the younger age groups had been noted as long as I 3 years ago by Gilliam et al. (1961). It was argued in subsequent correspondence that the change in the Journal of Thoracic and Cardiovascular Surger_y(Weiss 1g71), reported by Langston was accounted for by the fact that much of the material was derived from a Veteran’s Hospital and that many of the patients having been involved in the First World War would necessarily be reaching their sixties by the end of 1970. However, the change had already been noticed in this country, and a brief study of the figures soon showed that Langston’s observa-
Age under 45
100% 90%
45-54
55-64
65-74
75-
FIG. 13. The change in the age distribution of men with bronchial between
carcinoma
in the USA
1950 and 1969
tion was valid. Subsequently figures have been obtained from the Department of Health, Education and Welfare in the USA, and there is no doubt that the pattern on the two sides of the Atlantic is much the same, although the change is not so marked in the USA (Fig. 13). Springett (1966) observed that the increase in mortality in the younger age groups had stopped, and that thus the increase in the incidence of the disease had ceased in the group born in the first decade of the century. On the other hand, since the publication of his paper the incidence has continued to rise in the older age groups. This rise has now ceased in the 60-64 group in men, whereas, when his paper was written, it was levelling off in the 55-59 group. His prediction is seen to be correct. The figures presented show that not only has the incidence fallen in the younger men in the last decade, but also that it has risen among the older men. This alone would account for the higher proportion of patients presenting
THE
CHANGING
PATTERN
OF
BRONCHIAL
CARCINOMA
257
for treatment of bronchial carcinoma in their seventh and eighth decades. On top of this, the proportion of the population in the age groups principally at risk has also changed during the last twenty years, there being no less than 37% more men alive between the ages of 60 and 6g years in 1970 than there were in 1950. As almost the highest incidence of bronchial carcinoma falls in this age group, it is not surprising that more patients require treatment. The changes over the years in the women have been different. There has been no fall in the incidence in any age group, and their highest rate is still in the 75-79 years age group. The slowing in the rise in the annual rate has been going on in America at least since 1914 in both men and women (Gilliam et al. 1961) and the actual fall in the rate in the younger men started as long ago as 1950-5. As time has passed the rate has started to fall in men in this country in groups of ever increasing age, and it has fallen in the last 5 years in the 6o-64-year-olds. If this trend goes on, cases will probably present in increasing numbers for some years to come particularly if the expectation of life continues to increase. It is likely, however, that more and more patients will be seen who are well into their seventies in whom the wisdom of an offer of surgery will be thus open to question. We may therefore already be close to the time when the number of candidates for surgery may begin to fall. As there is no sign of a fall of the incidence in any age group among the women, an increasing number of patients of that sex are likely to develop bronchial carcinoma, and the ratio of men to women will continue to fall. It is interesting to speculate on the cause of these changes. Are they due to the discovery of the relationship of cigarette smoking to bronchial carcinoma and the subsequent national campaign against the habit ? This seems a likely suggestion until it is realized that the fall in the percentage increase in the rate and eventually of the rate itself in the younger age groups was happening as long ago as 1950. It seems more likely that the fall in the percentage rate of increase which dates back for at least fifty years has eventually led to an actual fall in the rate itself. This process has progressed steadily over many years, and represents the natural history of carcinoma of the bronchus. It is not clear why this natural history should be different in different countries and why for instance Japan seems to be at a point similar to that in the 1930s here. Perhaps it will eventually run the same course in the Far East as it has in the West. On the other hand, the fact that there is no fall in the rate in any age group amongst the women in this country may well be due to their relatively recent acquisition of the smoking habit, and the upward trend amongst them may persist for some years to come. As against this, the recent rise in the incidence of bronchial carcinoma amongst the women in Taiwan (Luh et al. 1974) has been much greater than that in the West, but very few of them smoke (2.3%). Lastly, can the change in some way be due to changes in the amount of atmospheric pollution ? This seems unlikely, for if it were so the considerable difference in the trends in the two sexes would not have been observed even if allowances were made for their different occupations.
258
BELCHER
It seems likely that what is being observed is the long drawn out process of the development and the decline of an individual disease, and that the timing of the process is different in the two sexes and in different parts of the world. Summary The age incidence of bronchial carcinoma in England and Wales is rising. In one series the proportion of the patients operated on over the age of 65 years rose from I 2% in 1950-5 to 37% in 1970-4. 3. This change reflects the national figures in both men and women. 4. The proportion of the population in the ages at risk has risen substantially, particularly amongst men, in the last 20 years, but this does not nearly account for the rise in the incidence in the older age groups. 5. The rate continues to rise in the patients over 65 years of age, but is now falling in all groups of men below that age. It is still rising in all age groups of women. 6. As time has passed the rate has begun to fall in men of older age groups. 7. The sex ratio continues to fall. 8. The process described has been going on for at least 50 years, and it is suggested that the decline in the younger age groups represents the natural history of bronchial carcinoma in the community. g. The timing of the change in mortality is different in different parts of the world and in the two sexes. IO. It is predicted that the number of men with broncial carcinoma fit for surgery may shortly start to fall in this country. I.
2.
ACKNOWLEDGEMENT
My thanks are due she took in preparing
to Mrs G. Dickens the data on which
of the Registrar General’s Office much of this paper is based.
for
the
great
trouble
REFERENCES
BATES, M. (1970) Results of surgery for bronchial carcinoma patients aged seventy and over. Thorax, 25, 77. BELCHER, J. R. & ANDERSON, R. (1965) Surgical treatment of carcinoma of the bronchus. Br. med. 948. GILLIAM, A. G., MILMORE, B. K. & LLOYD, J. W. (1961) Trends of mortality attributed to carcinoma of the lung. The declining rate of increase. Cancer, N.T., ‘4, 622. LANGSTON, H. T. (1972) Lung cancer, future projection. thorac. cardiovasc. Surg., 63, 432. LUH, K. T., Kvo, S. W., LUI, C. C., YANG, S. P. & CHEU, K. P. (1974) Primary lung cancer in Taiwan. Formosa med. Ass., 73, 129. SPRINGETT, V. H. (1966) The beginning of the end of the increase in mortality from carcinoma of the lung. Thorax, 21, 132. WEISS, W. (1972) Lung cancer, future projection. thorac. cardiovasc. Surg., 34, 131.
J., iii,
3.
3.
3.
ADDENDUM This paper was based on figures up to the end of 1970, and since occurred. The rate in men, up to 1973, is now almost static, and has 70; and the rates in women up to 44 are now beginning to fall.
then never
two changes have risen in men over
THE
CHANGING
PATTERN CARCINOMA
OF BRONCHIAL
J. R. BELCHER The London
Chest Hospital
and Middlesex
Hospital,
London
age incidence of bronchial carcinoma in England is changing: those dying of the disease are getting older, and this is true for both sexes. Springett (1966) inferred this and Langston (1972) observed it among his patients in the USA. This paper is concerned with the pattern of change in both sexes in the United Kingdon.
THE
Surgical
Series
Initially a study was made of the age distribution in my surgical series of 1478 patients by 5-year periods and 5-year age groups (Fig. I). This showed that the peak incidence of bronchial carcinoma among those operated on between I g5o and 1955 and between I 956 and 1960 was in the 56-60 years age group, whereas in the next decade it was in the 61-5 age group. It also showed that the proportion of patients under 50 years of age was steadily falling (from 25% in 1950-5 to 7% in rg7o-4), and that the proportion of patients operated on over the age of 65 had risen (from I 2 o/o in I 950-5 to I 7 o/o in I 970-4). Among the women there had been similar changes: a fall in the proportion under 50 from 19% to I 2% and a rise in the proportion over 65 from 6% to 32% (Fig. 2). With the increasing incidence of the disease in the whole population during these two decades, the number of patients operated on rose steadily from 214 in the 1950-5 period to 3 I 6 between 1970 and 1974. National
Figures
These changes might have been due to a change in surgical policy, for after a study published in 1965 (Belcher & Anderson 1965) there was some reluctance to operate on patients over the age of 70. This reluctance was dispelled by a subsequent publication (Bates 1g7o), and more recently the policy has been to disregard chronological age, with the result that a substantially larger proportion of patients over 70 have been operated on. At the same time, a considerable increase has occurred in the number of patients in this age group who have presented for treatment. The national figure given by the Registrar General for England and Wales have therefore been studied to seek the cause of this change, and these figures will be used from now on. (Reccivedforpublication 3unc 1975)
BELCHER
248
9 of
20-
TOW cuu In 5uq1u1 5wlU 8%
1970-74 lO-
1960-54
19xbl4d
/’
I 41145
FIG. I. The age distribution
FIG.
2. The age distribution
..l 1950-54
,
I 4ww
I
I
51155
56/w
of men with bronchial carcinoma in 3 periods of I0 years
of women with bronchial carcinoma in 3 periods of IO years
I 61165
I 66/70
I 711
in my surgical series, 1950-74,
in my surgical series, 1950-74,
THE
CHANGING
PATTERN
OF
BRONCHIAL
CARCINOMA
249
7.000Actual NUUlbW of
6.0005,000-
Registered Deaths Men
4.0003,000-
I 1950
FIG.
3. The
numbers
of men in England and carcinoma, 1950-70,
I 1955
I 1960
I 1965
Wales registered in 3 periods of
1,800
IO
I 1970
as having years
died
from
bronchial
died
from
bronchial
60-69
1,600 1,400 Actual Number
! 1,200
of 1,000 Registered Deaths
800
Wunen 600
FIG. 4. The
numbers
I
I
lg!io
1955
I
1960
I
1965
1 1970
of women in England and Wales registered as having carcinoma, x950-70, in 3 periods of 10 years
BELCHER
250
The actual numbers of persons registered as having died from bronchial carcinoma (ICD 162, 163) in three different age groups are shown in Figs 3 and 4. There was an enormous rise in the number of men over the age of 60 years dying of bronchial carcinoma between 1950 and 1970 (3722 to IO 414). A similar rise, from 638 to 1759 had occurred among the women. During the same period there had been a fall in the number of men under the age of 50 registered as dying from the disease, but a rise in the women in the same age group. Thus the surgical series reflects the national figures. Reasons
for Change
of Incidence
There are at least two possible reasons for the change of incidence: the size of the population at risk in different age groups could have changed, or the death rate of that population could have altered. In fact both have happened, but by far the most important factor was the rise in the incidence in the older age groups. Change of $opulation Figs 5 and 6 show that between I g5o and I g7o there was a substantial increase in the population in the age groups where the risk of developing bronchial TABLE
I. POPULATION
IN ENGLAND
AND WALES,
Igy-70
Age group (years)
1950 (million)
1970 (million)
Men 50-59 60-69
2’37 “73
3.01 2’37
640 000 (27%) 640 000 (37%)
Women 50-59 6o-G
2.8 2'21
3.01 2-81
210 000 (7’5%) 600 ooo (27%)
Increase
carcinoma is at its highest. Between the ages of 50 and 5g it has risen 20% in and 7.5% in women, and between 60 and 6g it has risen 37% and 27% respectively. Thus the total number of men alive in this older age group has gone up 640 ooo, and it is thus scarcely surprising that the number presenting with bronchial carcinoma in this age group has also increased (Table I). Could the increase in the number at risk have been responsible for the whole change in the incidence? The answer is ‘No’. Assuming that the death rate from lung cancer per IOO ooo of population had remained unaltered between 1950 and 1970, the number of men registered in 1970 would have been 5700, whereas in fact it was I o I I 4. Thus the rise in rate per I oo ooo in the older age group was largely responsible for the rise in numbers. men
Change in rate Between I g5o and I 970, the overall rate per I oo ooo for bronchial carcinoma rose from 4go to 1051 in men and from go-3 to 2 16 in women (Fig. 7). The
THE
CHANGING
PATTERN
OF
BRONCHIAL
CARCINOMA
251
change in rate has varied widely in different age groups and in the two sexes. Springett (1966) had already observed that a fall in the rate in younger men had been apparent since the late 1g4os, and indeed this rate is now falling up as far as the 60-64 age group (Fig. 8), though this has only happened between 1965 and 1970. Prior to this date, the rate was rising. This rise is now slowing among men, but not among women (Fig. 9). 2 million
1.5 million
1 million
1 -
_
o.5 millio” 1
45/49 50154 55/59 bOtb4 65169 70174 75/79
FIG.
5. The
changing
population represents
of men at risk between 1950 and the increase in the number alive
1970.
The
hatched
area
The
hatched
area
1 mllllon
0.5 million
c
,
,
(
(
(
(
,
45449 50/54 55159 bO/b4 65/69 70174 75/79 FIG.
6. The
changing
population indicates
of women at risk between 1950 and the increase in the number alive
1970.
The factors by which the rates have changed in these twenty years are shown in Tables 3 and 4. The older the men get, the greater the rise in the rate of the disease; on the other hand, the rate among women in all age groups has risen by a similar factor (twice). The peak rate for men now occurs between 70 and 74, while in 1950 it was between 65 and 69; in women it occurs between 75 and 26
RELCHER
252
01
FIG.
7. The
rising
incidence
’
I
1950
1955
of bronchial
I 1960
carcinoma
in inen
1950
1955
1960
of bronchial
carcinoma
I
I
1965
1970
and
women
between
I g5o and
I g7o
in s-year
age
7,000 6,0005,0004,000 3,000z,ooo-
FIG.
8. The
attack
rates
in men
1965
between
1950
1970
and
1970,
groups
79, as it did in 1950. The unique feature of bronchial carcinoma noted by Springett still holds: the rate falls after the middle seventies. The change in the rates of bronchial carcinoma in different age groups has been going on for a long time; indeed, a fall in the annual percentage rise in men has been reported as long ago as I g 14 (Gilliam et al. 1961) and Springett noted that there was no longer a rise in the 40-45 age group by 1950. A study was therefore made to see if this tendency persisted. The result is shown in Fig. I o. There has been a fall in all the percentage rises of incidence over each 5-year
THE
CHANGING
PATTERN
OF
BRONCHIAL
253
CARCINOMA
800 _ 700 -
.
65-69
600 500 400 300 200 lOO-
FIG.
g. The
attadk
rates
A I
I
I
I
1950
1955
1960
1965
of bronchial
carcinoma in women periods
40-44
1970
between
1950
and
1970,
in 5-year
70% -
60% 50% 40% 30% 206 10% -
-10
I
1950-,54
FIG.
IO. The
percentage
change
in the
I
I
,
55-59
60-64.
65-70
rates
in different 1970
age groups
of men
between
1950
and
period in each age group of men, and the rise has changed to a fall progressively earlier in the younger groups. Thus the incidence fell in 1954 for the 45-49 group, but not until rg7o for the 60-64 group; the 70-74 age group still shows a rise. The percentage rise in the total rate for the male population is also decreasing sharply, from 42% in 1950-5 to 9% in the most recent 5-year period (Fig. I I). The importance of these changes in the prediction of the future incidence of bronchial carcinoma is obvious.
BELCHER
254 TABLE
2.
CHANGE
Age grouj (years)
IN INCIDENCE BETWEEN '950
Increase
40-44
OF AND
BRONCHIAL I970
Increase
in men
x 0.85 x 0.87 None x 1.5 x 1.7 x2.4 x4.0
45-49 50-54
55-59 60-64 f-?-69 70-74
CARCINOMA
in women x 1.5 x2.1 x2.2 x2.1
x2.5 x2.0 x2.0
40%
30%
20%
10%
FIG.
I I. The
percentage
change
overall
in men
between
I g5o
and
I g7o
Changes in sex ratio It has been known for some time that the sex ratio of bronchial carcinoma has been falling in the United Kingdom. The expectation of life has been increasing in both sexes, but the increase in the population at risk has been greater in men than in women, so it might have been expected that the sex ratio would have increased. This has not happened; indeed, the reverse has been the case. The ratio for the rate has fallen from 5.4 to I in 1970 to 4-g to I in 1970, and the ratio for the total numbers from 5.1 to 4.6 to I in the same period. Table 3 shows how the ratio has changed in the various age groups and these changes are implicit in the wide differences in the change of incidence in the two sexes between 1950 and 1970. It can be seen that there is a steady rise in the ratio as age advances in 1970, whereas in 1950 the peak was reached in the 55-59 age group.
THE
CHANGING
PATTERN
OF
TABLE 3. SEX BRONCHIAL
BRONCHIAL
RATIO (M CARCINOMA
BETWEEN
CARCINOMA
:
1950
F)
OF BY
AND
DEATHS AGE
255
FROM GROUP
1970
Sex ratio
Age group (years)
‘950
40-44
4’4
45-49 50-54 55-59 60-64
7’8 7’7 :: I1 8.4 : I 8.4 : I 6.7 : I 5 : I
65-69
70-74
‘970 4:’
: I
3.g j : 5.2 : I 6.5 : I 8 : I 8.6 : I
Age under 45
45-54
55-64
65-74
75-
FIG.
I 2.
The
I
O%I projection
of Springett’s
histogram.
I The
1946
I and
1963
figures
are his
Changes of proportion of patients in various age groups The changes predicted by Springett (1966) have occurred. He showed that the proportion of patients in the 65-70 age group was rising up to 1963 and that in the younger age group (45-54 years) it was falling. This trend has continued. Fig. 12 shows the present figures added to the diagram which he drew in x966. The proportion in the younger group has fallen from 24% in 1946 to 9% in 1971, whereas the proportion in the 65-70 years age group has risen from 24% to 40% in the same period. Figure I 2 shows clearly the shift in the age incidence of bronchial carcinoma in Great Britain which led to this investigation.
BELCHER
256
Discussion The change in the age pattern of bronchial carcinoma was first noticed by Springett ( 1966) and then by Langston (1g72), although the slowing down in the rise of the death rate in the younger age groups had been noted as long as I 3 years ago by Gilliam et al. (1961). It was argued in subsequent correspondence that the change in the Journal of Thoracic and Cardiovascular Surger_y(Weiss 1g71), reported by Langston was accounted for by the fact that much of the material was derived from a Veteran’s Hospital and that many of the patients having been involved in the First World War would necessarily be reaching their sixties by the end of 1970. However, the change had already been noticed in this country, and a brief study of the figures soon showed that Langston’s observa-
Age under 45
100% 90%
45-54
55-64
65-74
75-
FIG. 13. The change in the age distribution of men with bronchial between
carcinoma
in the USA
1950 and 1969
tion was valid. Subsequently figures have been obtained from the Department of Health, Education and Welfare in the USA, and there is no doubt that the pattern on the two sides of the Atlantic is much the same, although the change is not so marked in the USA (Fig. 13). Springett (1966) observed that the increase in mortality in the younger age groups had stopped, and that thus the increase in the incidence of the disease had ceased in the group born in the first decade of the century. On the other hand, since the publication of his paper the incidence has continued to rise in the older age groups. This rise has now ceased in the 60-64 group in men, whereas, when his paper was written, it was levelling off in the 55-59 group. His prediction is seen to be correct. The figures presented show that not only has the incidence fallen in the younger men in the last decade, but also that it has risen among the older men. This alone would account for the higher proportion of patients presenting
THE
CHANGING
PATTERN
OF
BRONCHIAL
CARCINOMA
257
for treatment of bronchial carcinoma in their seventh and eighth decades. On top of this, the proportion of the population in the age groups principally at risk has also changed during the last twenty years, there being no less than 37% more men alive between the ages of 60 and 6g years in 1970 than there were in 1950. As almost the highest incidence of bronchial carcinoma falls in this age group, it is not surprising that more patients require treatment. The changes over the years in the women have been different. There has been no fall in the incidence in any age group, and their highest rate is still in the 75-79 years age group. The slowing in the rise in the annual rate has been going on in America at least since 1914 in both men and women (Gilliam et al. 1961) and the actual fall in the rate in the younger men started as long ago as 1950-5. As time has passed the rate has started to fall in men in this country in groups of ever increasing age, and it has fallen in the last 5 years in the 6o-64-year-olds. If this trend goes on, cases will probably present in increasing numbers for some years to come particularly if the expectation of life continues to increase. It is likely, however, that more and more patients will be seen who are well into their seventies in whom the wisdom of an offer of surgery will be thus open to question. We may therefore already be close to the time when the number of candidates for surgery may begin to fall. As there is no sign of a fall of the incidence in any age group among the women, an increasing number of patients of that sex are likely to develop bronchial carcinoma, and the ratio of men to women will continue to fall. It is interesting to speculate on the cause of these changes. Are they due to the discovery of the relationship of cigarette smoking to bronchial carcinoma and the subsequent national campaign against the habit ? This seems a likely suggestion until it is realized that the fall in the percentage increase in the rate and eventually of the rate itself in the younger age groups was happening as long ago as 1950. It seems more likely that the fall in the percentage rate of increase which dates back for at least fifty years has eventually led to an actual fall in the rate itself. This process has progressed steadily over many years, and represents the natural history of carcinoma of the bronchus. It is not clear why this natural history should be different in different countries and why for instance Japan seems to be at a point similar to that in the 1930s here. Perhaps it will eventually run the same course in the Far East as it has in the West. On the other hand, the fact that there is no fall in the rate in any age group amongst the women in this country may well be due to their relatively recent acquisition of the smoking habit, and the upward trend amongst them may persist for some years to come. As against this, the recent rise in the incidence of bronchial carcinoma amongst the women in Taiwan (Luh et al. 1974) has been much greater than that in the West, but very few of them smoke (2.3%). Lastly, can the change in some way be due to changes in the amount of atmospheric pollution ? This seems unlikely, for if it were so the considerable difference in the trends in the two sexes would not have been observed even if allowances were made for their different occupations.
258
BELCHER
It seems likely that what is being observed is the long drawn out process of the development and the decline of an individual disease, and that the timing of the process is different in the two sexes and in different parts of the world. Summary The age incidence of bronchial carcinoma in England and Wales is rising. In one series the proportion of the patients operated on over the age of 65 years rose from I 2% in 1950-5 to 37% in 1970-4. 3. This change reflects the national figures in both men and women. 4. The proportion of the population in the ages at risk has risen substantially, particularly amongst men, in the last 20 years, but this does not nearly account for the rise in the incidence in the older age groups. 5. The rate continues to rise in the patients over 65 years of age, but is now falling in all groups of men below that age. It is still rising in all age groups of women. 6. As time has passed the rate has begun to fall in men of older age groups. 7. The sex ratio continues to fall. 8. The process described has been going on for at least 50 years, and it is suggested that the decline in the younger age groups represents the natural history of bronchial carcinoma in the community. g. The timing of the change in mortality is different in different parts of the world and in the two sexes. IO. It is predicted that the number of men with broncial carcinoma fit for surgery may shortly start to fall in this country. I.
2.
ACKNOWLEDGEMENT
My thanks are due she took in preparing
to Mrs G. Dickens the data on which
of the Registrar General’s Office much of this paper is based.
for
the
great
trouble
REFERENCES
BATES, M. (1970) Results of surgery for bronchial carcinoma patients aged seventy and over. Thorax, 25, 77. BELCHER, J. R. & ANDERSON, R. (1965) Surgical treatment of carcinoma of the bronchus. Br. med. 948. GILLIAM, A. G., MILMORE, B. K. & LLOYD, J. W. (1961) Trends of mortality attributed to carcinoma of the lung. The declining rate of increase. Cancer, N.T., ‘4, 622. LANGSTON, H. T. (1972) Lung cancer, future projection. thorac. cardiovasc. Surg., 63, 432. LUH, K. T., Kvo, S. W., LUI, C. C., YANG, S. P. & CHEU, K. P. (1974) Primary lung cancer in Taiwan. Formosa med. Ass., 73, 129. SPRINGETT, V. H. (1966) The beginning of the end of the increase in mortality from carcinoma of the lung. Thorax, 21, 132. WEISS, W. (1972) Lung cancer, future projection. thorac. cardiovasc. Surg., 34, 131.
J., iii,
3.
3.
3.
ADDENDUM This paper was based on figures up to the end of 1970, and since occurred. The rate in men, up to 1973, is now almost static, and has 70; and the rates in women up to 44 are now beginning to fall.
then never
two changes have risen in men over
