Jul 1, 1989 - This study compared cancer mortality among the Seneca Nation of Indians (SNI) between 1955 and 1984 with cancer patterns exhibited by the ...
Cancer Mortality in a Northeastern Native American Population MARTIN C. MAHONEY, P H D , ~ARTHUR M. MICHALEK, PHD,’ K. MICHAEL CUMMINGS, PHD, MPH,t PHILIP C. NASCA, P H D , ~AND LAWRENCE J. EMRICH, PHDS
This study compared cancer mortality among the Seneca Nation of Indians (SNI) between 1955 and 1984 with cancer patterns exhibited by the general population of New York State (NYS), exclusive of New York City. Cancer mortality among the SNI was compared with cancer mortality in NYS using age and sex standardized mortality ratios (SMR). Deficits in overall cancer mortality were noted among both SNI males (SMR = 78) and females (SMR = 73). Results from this investigation will contribute to the understanding of patterns of malignant disease mortality among native peoples and may be of benefit for monitoring the impact of cancer mortality among the SNI and other Native American groups. Cancer 64:187-190. 1989.
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has been generally well documented through studies conducted among the general populations of various areas. Unfortunately, deviations in cancer mortality among specific subgroups may be overlooked due to masking of these differences within the more homogeneous general population. It therefore becomes important to consider patterns of cancer mortality among defined racial and ethnic groups. Studies of cancer mortality in Native American populations have suggested disease patterns that differ from the general population. Mortality deficits have been noted among Native males for deaths due to all cancer sites combined,’-5 as well as for deaths due to malignancies of the r e ~ t u m , p~ a. ~ n~reas,~ lung,’-6 ,~ and prostate,2*4*’ and for lymphoma^^.^ and leukemias.234While a group of Native males in the United States (U. S.) has demonstrated a deficit of kidney cancer deaths,’ other studies have reported an excess of deaths due to this Excess mortality has also been observed among Native American males for gallbladder ~ a n c e r . ~ . ~ Deficits in overall cancer mortality have also been reported among Native fern ale^.^*^*^ Only one investigation has suggested excess mortality for all cancer sites combined ANCER-RELATED MORTALITY
From the Departments of *Education, tEpidemiology and Cancer Control, and $Biomathematics,Roswell Park Memorial Institute, Buffalo, New York, and the §Bureau of Cancer Epidemiology, New York State Department of Health, Albany, New York. Supported in part through NCI Clinical Cancer Education Training Grant R25CA18201-12. The authors thank the Seneca Nation of Indians for cooperation and support during this project and Dolores Keneston-Smith for help in preparation of this manuscript. Address for reprints: Martin C. Mahoney. PhD, Bureau of Cancer Epidemiology, New York State Department of Health, Corning Tower, Room 565, Empire State Plaza, Albany, NY 12237. Accepted for publication: July 11, 1988.
in Native Americans; this observation was noted among Native females in Ontario, Canada.’ Site-specific mortality deficits have been reported for deaths due to cancers of the C O ~ O1ung,2*’*6 ~ , ~ . ~b r e a ~ t , ~ ?and ~ * ’uterus5 and for leukemias.2*sElevated mortality among Native females has been noted for cancers of the gallbladder,’,2*4,5 pancreas?5 ~ e rv ix ,~ .~and -’ kidney.’.2 Mixed results have been observed among Native females for mortality due to cancers of the r e ~ t u m ~and . ~ .ovary. ~ 1,2*43 Previous investigations of cancer mortality among Native Americans have been restricted to Native groups residing in the southwestern United States, across Alaska, and throughout Canada. This study investigated cancer mortality among members of the Seneca Nation of Indians between 1955 and 1984. The Seneca Nation of Indians (SNI) is the largest of six Iroquois tribes occupying lands in New York State (NYS).
Methods Study Cohort The SNI reside on the Allegany and Cattaraugus reservations in Western New York State. Other Senecas reside in and around the central city areas of Erie and Niagara Counties and throughout other parts of New York State. According to tribal records, Senecas living outside of New York State reservations areas account for less than 20% of the total SNI population (SNI Biennial Report, 1984).
The SNI maintain an official listing of all tribal members in annual tribal rolls. These records provide proof of membership in the SNI. The SNI is a matrilineal society and thus membership is conferred at birth. Information on the addresses of tribal members and all births and deaths are recorded in the annual roll books. The tribal
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roll is also used to determine eligibility for Indian Health Services and Bureau of Indian Affairs benefits. The cohort for this study consisted of all members of the Seneca Nation of Indians enrolled during 1955 and identified as residents of New York State. This yielded 3,262 cohort members (48.2%males, 5 1.8%females) who were followed until their time of death or until the end of 1984. The study cohort was fixed, births occumng after 1955 were not added to the study cohort. This method may have introduced a bias by failing to detect childhood cancer deaths occumng among SNI members. However, younger persons account for only a small fraction of the total cancer burden in a population. Moreover, given low cancer mortality reported among other Native American groups, the exclusion of subsequent births into the SNI study cohort after 1955 is unlikely to have undercounted incident cancers among the cohort. There was no outmigration among the cohort, although loss to followup may have occurred as a result of cohort members taking up permanent residence outside of New York State. Any deaths occurring in states adjacent to New York are likely to have been reported to New York State through reciprocal reporting agreements in place since the 1930’s. Matrimonial records were reviewed to update name changes among SNI females. To verify the consistency and accuracy of tribal recordkeeping, a 10%random sample was selected from among all cohort members. These individuals were manually traced through annual tribal roll books until time of death or through 1984. Overall, 94.5% of these persons were successfullytraced through tribal records; slight differences in the percentage tracked were apparent among males (99.4%)and females (88.6%).This demonstrated that annual updates to tribal roll books were both consistent and accurate. Study Design A retrospective cohort study design was used to examine patterns of cancer mortality among this Native American population from January 1, 1955 until December 31, 1984. The cohort included only SNI members identified as New York State residents. Endpoints for person-years calculations were; 1) date of death; or 2) survival to the end of followup. Sex-specific person-year totals for the study cohort were accumulated over three ten-year intervals (1955-1964, 1965-1974, 1975-1984) and were partitioned into five-year age categories (0-4 years, 5-9 years, 10-14 years, . . . , 80-84 years, and 85-99 years). Person-years at risk observed among the SNI study cohort were multiplied by corresponding sex-, age-, and calendar-year specific New York State cancer mortality rates, exclusive of New York City, during 1960,’ 1970,7 and 1980 (New York State Department of Health), to yield
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expected numbers of cancer deaths during the study period. Denominator data was compiled from census enumerations of the New York State population, exclusive of New York City, during 1960,8 1970,8and 1980.9 This investigation relied on the New York State Department of Health for the identification of deaths among cohort members. Since all cohort members were known to reside in New York State, a roster of the cohort was submitted to the New York State Department of Health for a computer match against Vital Statistics records. Underlying cause of death reported on the certificate of death was recoded to the ninth revision of the International Classification of Diseases (ICD-9).1° Cancer deaths included ICD-9 codes 140-208. Additionally, a number of cancer deaths were identified through information provided by the New York State Cancer Registry as part of a search for incident cancers. Sex and age standardized mortality ratios (SMRs) were calculated based on cancer deaths occumng among the SNI between 1955 and 1984. Since the number of cancer deaths can be considered to follow a Poisson distribution, p-values were calculated using a two-tailed test. Confidence intervals (95%)were also calculated for each SMR using published tables for significance factors. ‘ , I 2
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Results
Distribution of Cancer Deaths A total of 65 deaths due to malignant neoplasms were observed among SNI males between 1955 and 1984. One additional male death was due to a neoplasm of unspecified nature of “other genitourinary organs,” however, this death was not included in analyses of malignant neoplasms since the malignant nature of this tumor was uncertain. Lung cancer (23.1%) accounted for the largest percentage of male cancer deaths followed by cancers of the colon (13.8%), rectum (10.8%),prostate (10.8%),and pancreas (7.7%) and leukemias and lymphomas (6.2%). A total of 56 deaths due to malignant disease were observed among SNI females during the study period. Lung cancer (2 1.4%) accounted for the largest percentage of female cancer deaths followed by cancers of the cervix (14.3%),breast (12.5%),colon (8.9%),and stomach (8.9%) and leukemias and lymphomas (4.1%).In addition to the 56 cancer deaths observed, one additional female death was due to a neoplasm of unspecified nature of “other genitourinary organs.” This death was not included in analyses of malignant diseases due to its uncertain nature.
Standardized Mortality Ratios Site-specific age standardized S M R s among males for the 1955-1984 period are presented in Table 1. A significant deficit of cancer mortality for all sites combined was
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Mahuney et al.
TABLE1. Standardized Mortality Ratios (SMR) for Cancer Mortality Among Seneca Nation of Indians-Males: ICD 9 code no. 140-208 140-149 151 I53 154 155-1 56 157 162 170-17 1 185 I88 189 200-202 203 204-208
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Observed deaths
Cause of death All malignant neoplasms Buccal cavity and pharynx Stomach Colon Rectum Liver and gallbladder Pancreas Lung Soft tissue$ Prostate Bladder Kidney Lymphomas Multiple myeloma Leukemias Other/unspecified sites
* Confidence Interval. P < 0.05. $ Bone & connective tissue cancem 1965-1984 only. One additional
noted among males (SMR = 78; CI = 60-99). Site-specific cancer mortality among males did not differ from expected. Table 2 presents site-specific SMR’s for cancer deaths among SNI females between 1955 and 1984. Females exhibited a significant deficit of deaths due to all malignant neoplasms combined (SMR = 73; CI = 55-95) between 1955 and 1984. Site-specific deficits in mortality were observed for cancers of the pancreas (SMR = 0; CI = 0-73) and breast (SMR = 42; CI = 17-54). Significantly elevated
65 4 3 9 7 2 5 15 1
7 2 1
3
0 I 5
Cause of death
140-208 140-1 49 151 153 154 155-156 157 162 170-17 1 174 180 179 and 182 183 188 I89 200-202 203 204-208 -
All malignant neoplasms Buccal cavity and pharynx Stomach Colon Rectum Liver and gallbladder Pancreas Lung Soft tissue§ Breast Cervix Uterus Ovary Bladder Kidney Lymphomas Multiple myeloma Leukemias Other/unspecified sites
One additional death from tumor of “other genitourinary organ” of unspecified nature was observed among females. This death was not included in analyses of cancer mortality. Confidence interval.
1955-1984
SMR
95% CI*
78t 167 66 I00 21 3 104 113 62 59 94 61 53 78 0 30
60-99 45-427 14-193 46- 190 86-439 13-375 37-264 35-102 1-328 38-194 7-220 1-294 16-228 0-290 1-167 -
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death from tumor of “other genitourinary organ” of unspecified nature was observed among males. This death was not included in analyses of cancer mortality.
mortality was noted for deaths due to cervical cancer (SMR = 27 1; CI = 117-533).
Discussion Overall cancer mortality among both SNI males (SMR 78; CI = 60-99) and females (SMR = 73; C1= 55-95) was significantly low during the entire thirty year study period for all sites combined. This observation is consistent with lower cancer mortality reported among Native =
TABLE2. Standardized Mortality Ratios (SMR) for Cancer Mortality Among Seneca Nation of Indians-Females: ICD-9 code no.
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Observed deaths 56 I 5 5 2 2 0 12 1 7 8 3 2 0 0 1 0 3 4
t P < 0.025.
1955-1 984
SMR
95% c1*
73t 100 154 48 72 88
55-95 3-555 50-360 16-1 12 9-260 11-318 0-73 84-284 2-46 1 17-87 117-533 10-143 5-141 0-2 I7 0-254 1-189 0-262 21-301
03 163 83 42 t 271t 49 39 0 0 34 0 103
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4 P < 0.05. $ Bone and connective tissue cancers 1965-1984 only.
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American males in the U. and in Canada.'*3,4Lower cancer mortality has been reported among Native American females in the U. S.235and in Canada3 for all sites com bined. Lung cancer mortality among both SNI males (SMR = 62; CI = 35-102) and females (SMR = 163; CI = 84284) did not differ from the standard population. Previously published studies of Native males'-6 have reported lung cancer mortality deficits. Lung cancer among Native females has demonstrated both similar'4 and decrea~ed'?~ mortality. Colon cancer mortality in SNI males (SMR = 100; CI = 46-190) and females (SMR = 48; CI = 16-1 12) was unremarkable. Decreased mortality for colon cancer has been reported among Native American females in New Mexico225 but not among Native females in Ontario, Canada.'.4 Native males in both the U. s.$and Canada4 have exhibited deficits of colon cancer deaths. While deficits in rectal cancer mortality have been reported among Native males in other area^,',^*^^' rectal cancer mortality among both SNI males (SMR = 2 13; CI = 86-439) and SNI females (SMR = 72; CI = 9-260) was comparable to the standard population. SEER' mortality data demonstrated a 22% excess of rectal cancer deaths among Native females in New Mexico. Dietary practices among the SNI were unavailable as part of this investigation. SNI females demonstrated a significant deficit of breast cancer deaths (SMR = 42; CI = 17-87) during the entire study period. This is consistent with low breast cancer mortality reported among other Native female populat i o n ~ . * This * ~ , ~observation of lower breast cancer mortality is likely associated with lower breast cancer incidence attributable to higher fertility patterns reported among Native American females.I3 While mortality due to pancreatic cancer among SNI males was unremarkable (SMR = 113; CI = 37-264), a deficit of pancreatic cancer deaths was observed among SNI females (SMR = 0; CI = 0-73). This mortality deficit has been previously described among Indian females in British Columbia, Canada: however, excess pancreatic mortality has been reported among Native females in New Mexico.'*' Cervical cancer mortality was significantly elevated among SNl females between 1955 and 1984 (SMR = 27 1; CI = 117-533). Other Native populations have also exhibited increased cervical cancer mortal it^.^-^ This excess may be partially attributable to under-utilization of cervical cancer screening program^.^,'^ Although use of cervical screening programs among Southwestern American Indians exceeded 60% among women age 20 years and older, only 27% of those over 50 years of age were ~creened.'~ Targetted screening of older SNI females seems warranted. S.275
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For several sites of cancer only a small number of observations were available resulting in wide confidence intervals around point estimates of cancer mortality. For this reason, point estimates of mortality for these sites must be interpreted cautiously. In addition, this investigation was unable to assess childhood cancer mortality due to the fixed cohort design, and more aptly describes adult cancer mortality in this population. Significant deficits in overall cancer mortality were noted among both SNI males and females. Females demonstrated site-specific deficits in mortality due to cancer of the breast and pancreas. Significantlyelevated mortality was noted only for cervical cancer. Site-specific cancer mortality among SNI males did not differ from expected. It would be of interest to expand this investigation to include all Native American groups in New York State to determine how cancer mortality among all Native Americans in New York State compares with other Native groups across North America. This research contributes to knowledge of cancer mortality among Native American populations. These results may prove useful for monitoring the impact of cancer mortality among the SNI and other Native American groups. REFERENCES 1. Young TK, Frank JW. Cancer surveillance in a remote Indian population in northwestern Ontario.Am J Pub Health 1983; 73(5):515520. 2. Surveillance, Epidemiology, and End Results: Incidence and Mortality Data, 1973-1977. Natl Cancer Instit Monogr 57, 1981. NIH Publication No. 8 1-2330. 3. Mao Y, Morrison H, Semenciw R, et al. Mortality on Canadian indian reserves 1977-1982. Can J Pub Health 1986; 77:263-268. 4. Gallaher RP, Elwood JM. Cancer mortality among Chinese, Japanese, and Indians in British Columbia, 1964-1973. Natl Cancer Inst Mongr 1979; 53239-94. 5. Creagan ET, Fraumeni JF. Cancer mortality among American Indians, 1950-1967. J Natl Cancer Inst 1972; 49(4):959-967. 6. Samet JM, Key CR, Kutvirt DM, et a/. Respiratory disease mortality in New Mexico's American Indians and Hispanics. Am J Public Health 1980 70492-497. 7. Cancer Incidence and Mortality in New York State, Exclusive of New York City, 1950-1972. Bureau of Cancer Control, New York State Department of Health, 1976. 8. U. S. Bureau of the Census, Statistical Abstract of the United States: 198 1 ( 102d edition.) Washington, DC, 198 1. 9. U. S. Bureau of the Census, General Population Characteristics, New York, PC80-1-934, Washington, DC,1982. 10. Manual of the International Statistical Classification of Diseases, Injuries and Causes of Deaths, ninth revision. Geneva, World Health Organization, 1977. 1 1. Mantel N. Appendix C. In: Haenszel W, Loveland DB, Sirken MG. Lung-Cancer Mortality as Related to Residence and Smoking Histones. 1. White Males. J Nut1 Cancer Instit 1962; 28:947-1001. 12. Bailar JC, Ederer F. Significance factors for the ratio of a poisson variable to its expectation. Biometries 196%20639-643. 13. Tafel S. National Center for Health Statistics, Characteristics of American Indian and Alaska native births, United States, 1984. Monthly Vital Statistics Report, Vol. 36, No. 3, Supp. DHHS Pub. No. (PHS) 87-1 120. Public Health Service, 1987. 14. Jordan SW, Key CR. Carcinoma of the cervix in Southwestern American Indians: Results of a cytologic detection program. Cancer 198 1 ; 47:2523-2532.
