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Bull Pan Am Health Organ 17(4), 1983.
EPIDEMIOLOGY AND ECOLOGY OF GASTRIC CANCER IN
COSTA RICA1
Rafaela Sierra* and Ramiro Barrantes
Costa Rica’s high incidence of gastric cancer and suitable data sourcesprovide
a good basis for sttuying the or&ins of this disease. The work reported here
assesses regional and other variation within the country in terms of the age and
sex of gastric canmr patients, the patients’ birthplaces and places of residence,
and various environmental factors.
Introduction residence of gastric cancer patients vis-a-vis
geographic areas with differing incidence
Among the diseases involving malignant levels; (c) to relate the data obtained to various
tumors, gastric cancer is the leading cause of ecological parameters-such as dietary,
death in Costa Rica (1-4). It has also been drinking-water, and soil constituents-that
found that the incidence of gastric cancer in could affect the incidence of gastric cancer.
Costa Rica and the mortality resulting from
the disease are exceeded only in Japan and Materials and Methods
Chile (‘5-8, 35). Within Costa Rica, however,
Moya de Madrigal (9) has found that this The sample employed consisted of 1,3 15
tumor occurs with proportionately greater fre- patients with gastric cancer. All persons with
quency in the central provinces than in the this disease who were listed in the records of
coastal provinces, and Miranda et al. (10) the National Registry of Tumors from April
have also discerned differences between cer- 1977 to March 1980 were included. The basic
tain regions of the country. Since 1977, when information obtained on each subject was as
cancer notification was made compulsory, a follows: (a) age at first diagnosis; (b) place of
national registry of tumors has maintained a birth (province and canton); (c) place of
precise record of cases throughout the coun- residence when the cancer was diagnosed
try. This latter circumstance, together with (province, canton, district); (d) condition
the frequency of the disease, makes Costa when the information was procured; (e) age at
Rica an especially suitable country for the in- death; and (f) the method used to reach the
vestigation of gastric cancer. diagnosis. The data were coded and analyzed
The objectives of the work reported here by computer.
were as follows: (a) to study the epidemiology Age-standardized rates, adjusted4 on the
of gastric cancer in detail, using data from the basis of the “Gorld population” (11), by sex,
National Registry ofTumors and other related were found for the country as a whole and for
sources; (b) to analyze changes in the areas of each canton (municipality) where gastric
cancer patients had been born. Using these
rates as a guide, the following zones of risk
lAlso appearing in Spanish in the Boletin de la OJcina
Sanitaria Panamericana, 95(6):495-506, 1983.
2Research Associate, Institute of Health Research 4Th’ IS adjustment was made by applying the age-
(INISA), University of Costa Rica, San JosC, Costa specific mortality figures for the study population to the
Rica. numbers of people in the comparable age groups of the
3Professor of Human Genetics and Deputy Director, “standard population,” so as to find the number of
Institute of Health Research (INISA), University of deaths that would have occurred in the standard popula-
Costa Rica, San Jo&, Costa Rica. tion if these age-specific death rates had prevailed.
343
344 PAHO BULLETIN l vol. 17, no. 4, 1983
were established: (1) very high risk-areas phosphorus, 1.0 milligram of iron, 0.5 milli-
with an incidence greater than 108 cases per grams of manganese, 0.3 milligrams of zinc,
100,000 inhabitants; (2) high risk-with an and 0.1 milligrams of copper per 100 milli-
incidence between 66 and 108 cases per liters of soil. Multivariate analyses were per-
100,000; (3) moderate risk-between 33 and formed, using specific computer programs, to
65 cases per 100,000; and (4) low risk- assess these factors’ possible influence upon
less than 33 cases per 100,000.5 the incidence of gastric cancer.
For each region defined, all of the epidemio- In addition, an effort was made to examine
logic variables cited above were analyzed so as possible correlations between rates of gastric
to examine the influences of sex, age, and cancer and certain nutritional parameters set
population movements upon disease rates in forth in works by the Ministry of Health of
the region. In addition, a retrospective study Costa Rica (12, 231, the U.S. Agency for In-
was made of trends in standardized gastric ternational Development (141, and the Nutri-
cancer death rates from 1960 to 1976, based tion Institute of Central America and Panama
on the annual statistical data for Costa Rica. (15).
For the purpose of assessing environmental
factors, data were obtained on variations in Results
drinking-water and soil constituents. Specif-
ically, the archives of the National Water Sup- The retrospective study of annual data indi-
ply and Sewerage System provided data on cated that mortality from gastric cancer de-
the physical-chemical analyses of drinking- clined by 26 per cent between 1960-1961 and
water samples in several areas; these samples 1975-1976 (Table 1). Similar declines in stan-
were taken during two months of the dry dardized gastric cancer mortality have been
season (January and February) and two observed in other countries (IS). Rates stan-
months of the rainy season (September and dardized by sex could not be obtained for this
October) during three years (1976, 1978, and period, but gross rates by sex were obtained,
1980). The data obtained included values for and it was found that the decline was greater
PH, total hardness, calcium hardness, among females. This trend has also been
magnesium hardness, and the samples’ con- observed elsewhere (2, 17, 18).
tent of iron, chlorides, silica, and sulphates in Overall, as Table 2 shows, the average an-
milligrams per liter. nual incidence of gastric cancer among males
Regarding soils, the Ministry ofAgriculture and females in Costa Rica, standardized on
provided data on the composition of soils in the basis of the “world population,” was 51.4
different parts of Costa Rica, based on soil cases per 100,000 for males and 25.6 cases per
samples processed at the Costa Rican Tropical 100,000 for females during the period 1977-
Farming Research and Training Center
(CATIE) in Sa.n Jo&. The factors considered
were pH and the samples’content of calcium, Table 1. Gastric cancer mortality in Costa Rica per
iron, potassium, phosphorus, zinc, magne- 100,000 inhabitants, standardized for age, in various
periods from 1960 to 1976.
sium, aluminum, and manganese. The levels
defined as low for each factor were a pH below Annual mortality per 100,000
Period
5.5, and less than 0.3 milliequivalents of alu- standardized for age
minum, 2.2 milliequivalents of calcium, 0.8
milliequivalents of magnesium, 0.20 milli- 1960-1961 51.00
1964-1966 49.30
equivalents of potassium, 1.0 milligram of 1970-1971 41.71
1972-1974 39.11
1975-1976 37.74
5Foreigners were not included in these data.
Table 2. The standardizeda annual incidence of gastric cancer in Costa Rica during 1977-1980, by age and sex per 100,000 inhabitants,
and the estimated male:female case ratio, in regions grouped according to levels of risk.
Age group (in years)
Regions, grouped
by level of risk 524 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-14 zzf5 Total
VT high risk:
Est. M:F case ratiob 4.0 3.0 0.3 3.0 2.4 0.8 3.5 3.6 4.2 2.5 2.3 2.1 2.5
Male rate 1.9 14.4 5.6 39.0 86.0 108.5 268.7 635.1 436.3 1,081.8 1,165.5 1,239.3 153.2
Female rate 0.0 4.6 16.9 12.1 34.9 130.9 67.6 116.3 101.5 400.8 508.9 414.6 56.6
H&h risk:
Est. M:F case ratio 0.1 0.3 1.0 3.0 1.0 1.1 1.3 2.6 1.9 3.0 2.4 2.7 2.0
Male rate 0.0 4.5 10.5 17.7 20.2 75.3 131.6 278.3 333.1 630.7 583.7 952.0 88.4
Female rate 0.2 12.7 10.1 5.5 19.8 66.2 102.7 102.8 171.7 188.8 257.0 324.1 40.4
Modnate risk:
Est. M:F case ratio 0.2 1.5 2.5 0.5 2.6 2.4 1.6 2.6 1.5 3.1 1.5 2.7 2.1
Male rate 0.0 9.1 11.5 2.5 35.9 58.4 63.9 109.1 136.4 465.3 306.5 527.8 50.8
Female rate 0.4 4.1 5.4 5.7 16.0 26.8 44.2 45.7 92.2 165.5 200.3 189.4 24.0
Low risk:
Est. M:F case ratio 1.0 0.3 1.0 2.5 2.3 1.8 2.2 1.2 1.3 1.4 1.0 1.1 1.3
Male rate 0.1 0.0 0.6 6.1 9.6 14.4 22.8 33.1 51.6 78.7 66.4 128.8 12.6
Female rate 0.0 2.7 1.4 2.5 4.9 9.5 11.3 30.7 44.9 61.8 76.4 121.8 10.6
Total:
Est. M:F case ratio 1.6 0.7 1.1 2.0 2.0 1.4 2.1 2.3 2.0 2.1 1.6 2.0 2.0
Male rate 0.2 3.4 5.8 10.7 27.7 48.1 80.0 156.6 168.9 374.2 345.4 523.6 51.4
Female rate 0.1 4.6 5.2 4.9 13.1 32.0 36.2 64.1 79.6 169.9 205.3 236.8 25.6
aAccording to the world population (11).
bEstimates based on the proportions of males and females in the population.
346 PAHO BULLETIN l vol. 17, no. 4, 1983
1980. Figure 1 takes regional data for males gastric cancer has been low. If the disease
during this period and shows how the levels of levels in the cantons are estimated by using
gastric cancer varied according to the subjects’ the birthplaces of female rather than male sub-
birthplaces. Except for four subregions in the jects, the rates involved are generally lower,
northwest province of Guanacaste, all the can- but the inter-canton differences are similar to
tons showing moderate, high, and very high those for males (see Figure 2).
levels of gastric cancer were found to be in the If the data are ordered according to the sub-
central part of the country. One group of can- jects’ places of residence instead of their birth-
tons (Acosta, Mora, Puriscal, TarrazG, and places, cantons with higher case-rates for both
Turrubares) with very high rates form a single males and females still tend to be concentrated
contiguous area which is the largest area of in the central part of the country. However,
this kind in the country. (Miranda et al. (10) the rates in these central localities, considered
previously reported that some of these regions as places of residence, are generally lower
had a high incidence of gastric cancer; and than when they are considered as birthplaces,
Salas (19) has reported that inhabitants of the because the patients have tended to emigrate
country’s central region run a greater risk of to regions with lower incidences. This move-
developing lesions of the gastric mucosa than ment of cancer patients corresponds to move-
do people in the coastal regions.) In most ment of the country’s general population (20,
other cantons, which have a variety of differ- 21).
ing geographic conditions, the incidence of Table 2 shows age and sex-specific inci-
Figure 1. The relationship between birthplaces and rates of gastric cancer
among males in Costa Rica, by region, as indicated by the birthplaces of
male patients whose cases were diagnosed in 1977-1980.
ATLANTIC OCEAN
LEGEND (cases per 100,000 male inhabitants)
Very high (> 106 cases)
High (66-106 cases)
Moderate (33-65 cases)
Low (< 33 cases)
Sierra and Barranfes l GASTRIC CANCER IN COSTA RICA 347
Figure 2. The relationship between birthplaces and rates of gastric cancer
among females in Costa Rica, by region, as indicated by the birthplaces of
female patients whose cases were diagnosed in 1977-1980.
PACIFIC OCEAN
LEGEND (cases per 100,000 female inhabllanls)
n Very high (> 108 cases)
High (66-108 cases)
q Moderate (33-65 cases)
q LOW (< 33 cases)
dence rates and male:female case ratios for the Table 3 lists all the patients studied by their
country as a whole and for geographic regions place of birth, and then by their place of resi-
grouped according to levels of risk. These data dence when gastric cancer was diagnosed. The
have been standardized by age on the basis of resulting matrix shows that only 25 per cent of
the world’s population (II). the 283 gastric cancer victims born in the re-
Regarding the male:female case ratio, this gions of very high risk were living in such
is higher in the “very high” incidence regions regions when their disease was diagnosed.
(2.5: 1) than in the iow-incidence regions (Most had emigrated, and a majority of these
(1.3:1). Also, the male:female case ratio ap- were residing in regions of low risk.) Progres-
pears higher among those under 30 years of sively larger percentages (30.6, 52.5, and 79.5
age in the regions of very high incidence than per cent) of those born in the regions of high,
it does in any other regions. In Costa Rica as a moderate, and low risk, respectively, were
whole, above age 30 the male case-rate gener- residing in those regions when their disease
ally exceeds the female case-rate. was diagnosed. Conversely, a relatively high
In addition, these data indicate that 35 per percentage of the subjects residing in the very
cent of the males and 37 per cent ofthe females high risk regions when their disease was diag-
ill with gastric cancer were under 60 years of nosed (68.2 per cent) were born there, while
age. These results differ from those of Miran- smaller percentages (48.2, 51.5, and 25.4 per
da and colleagues (IO), who found that over cent, respectively) of the subjects residing in
70 per cent of the gastric cancer patients they the high, moderate, and low risk regions were
studied were under 60 years of age. born in those respective regions. These four
Table 3. Data showing the influence of population movements upon the incidence of gastric cancer in regions of Costa Rica with different
levels of risk for the period 1977-1980. For example, of the 283 patients born in regions of very high risk, 71 (25.1 per cent)
were living in such regions and 30 (10.6 per cent) were living in areas of high risk when their cases were diagnosed.
Similarly, of the 104 patients living in regions of very high risk when their cases were diagnosed, 71 (68.2 per cent)
had been born in such regions and 12 (11.5 per cent) had been horn in regions of high risk.
Reglow of residence, by mctdence level
Very high incidence regions High inctdence regions Moderate incidence regtons Low mcidence regtons Total (all regions)
7’0 of subpts % of subjects % of subjects % of subjects ‘70 of subjects
restding m born m residing in born in residing in born in residing m born in residing in born in
Regtons of birth, No of Indicated indicated No. of indlcated indlcated No of indicated mdlcated No. of mdtcated mdlcated No of indicated indicated
by mctdence level subJects reptons regions subjects regrons regions subjects regions regions subjects regions regions SubJects regtons regions
Very high incidence
regions 71 68.2 25.1 30 27.3 10.6 66 26.6 23.3 116 33.1 41.0 283 34.8 100
High incidence regions 12 11.5 6.9 53 48.2 30.6 40 16.2 23.2 68 19.4 39.3 173 21.3 100
Moderate incidence
regions 20 19.3 8.2 19 17.3 7.8 128 51.6 52.5 77 22 1 31.5 244 30.1 100
Low incidence regions 1 1.0 0.9 8 7.2 7 1 14 5.6 12.5 89 25.4 79.5 112 13.8 100
Total (all regions) 104 100 12.8 110 100 13.5 248 100 30.5 350 100 43.1 812 100 100
Sierra and Bawantes l GASTRIC CANCER IN COSTA RICA 349
regional differences are statistically significant cancer incidence is associated with higher con-
(Xi =203.9; p c0.01). centrations of potassium and iron, lower con-
It was also observed in this study that 86.8 centrations of zinc, and a lower pH. No
per cent of the subjects’ cases had been diag- significant associations were found between
nosed by traditional methods (biopsy or X-ray the incidence of gastric cancer and any of the
examination or both). Only 13.2 per cent of previously mentioned factors relating to
the diagnoses were based solely upon clinical drinking-water or diet.
examinations. It was also noted that 60 per
cent of those ill with gastric cancer died within Discussion
a year of the diagnosis.
Regarding the possible influence of soil The age-standardized data presented in
characteristics, a stepwise multiple regression Table 1 indicate that gastric cancer mortality
analysis was performed in order to assess the is declining in Costa Rica, and there is evi-
possible influence of certain soil characteristics dence that this decline is greater among
upon rates of gastric cancer. The only factors women than among men. The same phenom-
found to have any statistically significant asso- enon has been observed in other countries (8,
ciation with differences in the rates of gastric 16, I8, 22). The interpretation of this finding
cancer were potassium content, pH, zinc con- is not easy, but it seems reasonable to conclude
tent, and iron content in that order of impor- that environmental factors play an important
tance (see Table 4). The other factors con- role in development of the disease.
sidered were excluded from the regression Comparing our data with those of other
equation because they appeared to have no authors (1, 23), we find that in Costa Rica the
significant influence upon the dependent vari- prospects for gastric cancer patients’ survival
able. Overall, it should be noted that the vari- have improved very little during the last 20
ables of pH and the soil content of potassium, years. This leads to the conclusion that the de-
zinc, and iron appear to account for 22 per clining mortality observed is due to a declining
cent of the variation in the rates of gastric incidence of the disease in Costa Rica.
cancer. When the four variables are taken to- Despite this decline, however, gastric
gether, pH shows the highest significance, cancer’s incidence and mortality in Costa
yielding a total determination coefficient of Rica continue to exceed the incidence and
0.224. The signs of the regression coefficients mortality found in other countries. This fmd-
(b) are negative for potassium and iron and ing was reported previously by Strong et al.
positive for pH and zinc. In accordance with (5) for the period 1962-1963 and by Moya de
the regression conditions explained earlier, Madrigal (9) for 1956-1968. Miranda et al.
this indicates that an increase in the gastric (10) found incidence rates lower than those
Table 4. Stcpwise multiple regression analysis between selected soil features and the
rate of gastric cancer in different regions of Costa Rica during 1977-1980, treating the
latter as a dependent variable. No statistically significant correlations were found
between the rate of gastric cancer and soil levels of aluminum, calcium, copper,
magnesium, manganese, or phosphorus.
Independent Value IllCRFiS.2 V&e Standard Value Value
variable of R2 in R2 of b error of b of F OfP
Potassium 0.059 0.059 -0.746 0.347 4.61 <0.05
PH 0.138 0.079 0.548 0.211 5.86 <O.Ol
Zinc 0.193 0.055 0.619 0.280 5.73 co.01
Iron 0.224 0.031 -1.182 0.696 5.13 <O.Ol
350 PAHO BULLETIN l vol. 17, no. 4, 1983
presented here for the period 1969-1973, but ratio has varied considerably from one age
they used a different methodology. group to another. In this latter regard, below
Contrary to Tulinius’ (16) statement that age 30 gastric cancer has been commoner
gastric cancer rates are usually low in the among females than males in regions classified
tropics, Costa Rica, located in the tropical as having a high, moderate, or low incidence
zone, has very high rates of gastric cancer. of the disease. In contrast, however, the dis-
High rates of the disease have also been found ease struck a substantial preponderance of
in Cali, Colombia (24-26), and Tgchira, males under age 30 in regions where the inci-
Venezuela (27). Not much is known about the dence was very high. This last finding has not
situation in many other tropical countries be- been reported elsewhere in the literature,
cause in most instances reliable data are lack- which tends to reflect the idea that fewer men
ing. Moreover, many of those countries have than women become ill with the disease before
health problems such as malnutrition and in- reaching 30 or 35 years of age, but that after-
fectious diseases that cause death at ages wards the incidence among men increases
younger than those at which gastric cancer rapidly until it becomes double the incidence
typically becomes a serious health problem. In among women (31, 34, 36, 37).
Costa Rica, however, the distribution of The differences that we have observed be-
diseases has shifted recently from a prepon- tween male and female gastric cancer patients
derance of infectious and parasitic diseases to indicate that men are more susceptible than
a preponderance of certain noncommunicable women to carcinogens of the stomach, or that
diseases such as cancer, cardiovascular dis- they are more exposed to carcinogenic agents,
eases, and congenital diseases (28). This or that both conditions apply. There is thus a
change has occurred within a single genera- need for careful study of environmental condi-
tion. tions, the habits of males with gastric cancer,
The classification of regions as having very and appropriate control subjects.
high, high, moderate, and low incidences of It is reasonable to assume that most of the
gastric cancer makes it possible to study vir- Costa Rican cases studied were diagnosed ac-
tually all of the epidemiologic variables of the curately, since only 13 per cent of the diag-
disease and the environmental features of each noses depended solely on clinical findings. It
region, and to pinpoint noteworthy differences also appears that most cases were diagnosed
between regions. There is, of course, a direct only after the cancer was well advanced, since
and universally observed correlation between the survival rate was low and over 60 per cent
age and the incidence of gastric cancer among of the patients died within a year of the diag-
both men and women in all regions. It thus nosis. These data, plus other authors’ findings
appears that gastric cancer has a long latent that gastric cancer patients in Costa Rica have
period and that the risk of developing it is a low rate of survival (2, 3, 231, demonstrate a
greater after age 40 (24, 29). clear need for early diagnosis of gastric
Another relevant point is that the observed cancer, not only among people visiting health
incidence of gastric cancer is higher among centers for medical reasons but also among
men than among women in all regions. The those who believe themselves to be healthy,
reason for this difference is unknown, but especially those born in the country’s areas of
several authors have presented similar find- high risk. This need is underscored by recent
ings (30-34). studies showing that 90 per cent of the gastric
Our own study found that the male:female cancer patients operated on while the tumor is
ratio in Costa Rica has been higher in regions at an early state survive more than five years
where the disease risk was very high, high, or (38, 39).
moderate (as compared to low), and that the Both our study and other findings (25) sug-
Sierra and Bawantes 8 GASTRIC CANCER IN COSTA RICA 351
gest that a person’s birthplace is a major deter- have poor soils because of deforestation and
minant of the risk of gastric cancer. That is, a haphazard cultivation. In general, these prac-
relatively high proportion of those born in tices have been leaching the soil, causing it to
regions now classified as being “high risk” or erode, and increasing its acidity to a point
“very high risk” have proceeded to develop where today the soils in these areas yield only
the disease, even if they have moved from poor crops or are completely barren.
these high-risk areas to regions where the risk On a related subject, studies with experi-
is low. By and large, the cantons of high and mental animals have shown that deprivation
very high risk are cantons with net emigra- of certain trace elements during critical
tion, from which people have been emigrating periods of growth and development, or during
to the large banana plantations of the Atlantic long periods of adult life, can significantly
and southern Pacific regions or to the north- alter the functioning of the immune system. It
ern provinces of Alajuela, and Heredia (21). has also been shown that traces of metals in
In this vein, it seems noteworthy that studies the diet affect the onset and progression of a
of emigrant populations in other countries considerable number of neoplasias (42). To-
have shown that the incidence of gastric gether, these findings demonstrate a need to
cancer among people born in areas of high perform studies that assess multivariate pro-
risk remains high even after they have resided cesses, rather than simply attempting to corre-
in areas of low risk for many years (25, 40, late rates of gastric cancer with any single en-
41). vironmental factor.
The portion of our study dealing with soil With regard to the ways nutrition and food
samples found correlations between the inci- habits could affect the incidence of gastric
dence of gastric cancer and four variables- cancer in Costa Rica, very little can be said
pH, potassium, zinc, and iron. Each variable until specific studies are made. According to
considered alone had little influence, but studies by the Ministry of Health (8), the nu-
when all four variables were combined the tritional status of the Costa Rican population
linear pattern changed and pH assumed an has improved in recent years, and this may be
important role. In this regard, an article in one reason why gastric cancer rates are declin-
The Lancet (33) has stated that a possible corre- ing. However, the work done to date on nutri-
lation of zinc and copper with gastric cancer tion and diet in Costa Rica is not sufficient for
could be due to the levels of those metals being valid conclusions to be drawn about possible
affected by the presence of some other factor relationships between these factors and the in-
in the soil. It is also known that pH plays an cidence of gastric cancer. Therefore, this is an
important role in the behavior of elements in additional area that needs to be examined in
the soil and the absorption and utilization of detail, taking into account the findings now
such elements by plants. Moreover, some of available concerning the epidemiology of
the cantons with very high risk levels-includ- gastric cancer in our country.
ing Acosta, Mora, Puriscal, and Tarrazii-
ACKNOWLEDGMENTS
The authors wish to thank Dr. Juan Macaya of the School of Medicine,
University of Costa Rica, for his review and critique of the orginal draft of
this article.
352 PAHO BULLETIN . vol. 17, no. 4, 1983
SUMMARY
Because the incidence of gastric cancer is very More broadly, differences observed between
high in Costa Rica and suitable collections of data male and female case-rates indicate that men are
are available, the country affords a good opportuni- more susceptible than women to carcinogens of the
ty for studying the origins of this disease. The work stomach, or that they are more exposed to carcino-
reported here, conducted by Costa Rica’s Institute genic agents, or that both conditions apply.
of Health Research, concerns itself primarily with It also appears that the incidence of gastric
regional variations in gastric cancer morbidity cancer in Costa Rica has declined in recent de-
within the country. These regional variations are cades, a trend similar to ones observed in other
analyzed in terms of the age and sex of gastric countries. On the other hand, very little progress
cancer patients, the movement of such patients has been made in enhancing the survival prospects
from their regions of birth to other regions, and of the country’s gastric cancer patients; and since
local dietary, drinking-water, and soil features that that survival rate is low, with over 60 per cent of the
could affect the incidence of the disease. patients dying within a year of the disease being
This regional analysis shows that most regions diagnosed, there is a clear need for earlier diagno-
with very high rates of gastric cancer in 1977-1980 sis-especially among apparently healthy people
are located in the central portion of the country. living in high-risk areas. This need is underscored
When the data are ordered according to patients’ by recent studies showing that 90 per cent of the
birthplaces, the pattern is more pronounced than gastric cancer patients operated on while the tumor
when the data are organized by the patients’ places is at an early stage survive at least five years.
of residence at the time of diagnosis, because many Regarding soil features, some correlation was
patients had moved from high-risk areas to areas found between the incidence of gastric cancer in dif-
where the disease incidence was low. This move- ferent regions and soil pH, potassium content, zinc
ment of people who developed gastric cancer fol- content, and iron content. No statistically signifi-
lowed a more general population shift away from cant correlations were observed between the inci-
these central regions. dence of gastric cancer and other regional variables
Regarding the male:female case ratio, this ratio tested-including nutritional variables, drinking-
was found to be relatively high in regions where the water characteristics, and other soil constituents.
incidence of gastric cancer was very high, high, or The nature of these findings, together with other
moderate (233 cases per 100,000 inhabitants). available research findings, suggests a need for
Also, in regions of very high risk (> 108 cases per studies that examine the interactions of multiple
100,000 inhabitants) the male:female case ratio ap- variables.
pears very high among those under 30 years of age.
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Revista Mid&a de Costa Rica l&27-41, 1961. Conditions in the Americas: 1973-1976. PAHO Scien-
(2) L6pez, E. A., and H. Gon&.lez. Mortalidad tific Publication No. 364. Washington, D.C., 1978.
par cdncer en Costa Rica. Congreso Mkdico Centro- (7) Segi, M., H. Hattori, and R. Segi. Age-
americano, San Jo&, 1963. adjusted Death Rates for Cancer for Selected Sites (A-clas-
(3) Mena, H. Frecuencia de1 cheer en Costa sification) in 46 Countries in 1975. Segi Institute of
Rica. Acta MLdica Costarricense 7(1):19-26, 1964. Cancer Epidemiology; Nagoya, Japan, 1980.
(4) Costa Rica, Ministerio de Salud. Plan Nacio- (8) Logan, W.P.D. Cancers of the alimentary
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PRIMARY PNEUMONIC PLAGUE IN THE UNITED STATES
On 5 August 1983, plague was diagnosed in a girl 13 years of age in South Carolina. She
became ill while en route to Maryland from her previous residence in Santa Fe, New Mex-
ixo, and subsequently died. The area in which she had lived had been recognized as a lo-
cality where sylvatic plague was enzootic.
A chest radiograph taken before death revealed extensive pulmonary infiltrates. Ante-
mortem aspirations of the right inguinal lymph node demonstrated Gram-negative bipolar
staining bacilli on Giemsa stain. Both this aspirate and multiple cultures of blood yielded
Yersinia pestis. In addition, fluorescent antibody stains for Y. pestis were positive for spec-
imens consisting of blood smears, culture material, and pulmonary secretions.
Primary pneumonic plague has been described as rare in the United States, with only
three cases-all in laboratory workers-being reported between 1926 and 1975. However,
five persons have developed primary pneumonic plague since 1975, presumably as a result
of exposure to household pets with secondary plague pneumonia.
Recent investigations suggest that plague pneumonia (i.e., secondary to bubonic plague)
is more common. No transmission of pneumonic plague to contacts of patients with the
disease has been documented in the United States since 1925.
Delay in diagnosing and treating plague increases the potential for pulmonary involve-
ment and person-to-person transmission. In the past eight years, 32 (20 per cent) of 164
plague patients reported to the Centers for Disease Control have developed pulmonary
disease. Three (33 per cent) of the nine plague patients who had been interstate travellers
developed pneumonia, including the girl mentioned above.
Source: United States Centers for Disease Control, Morbidity nnd Mortality 32(32), 1983.
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