Rare cancers in Canada, 2006-2016: A population-based surveillance report and comparison of different methods for classifying rare cancers

BACKGROUND

The cumulative burden from rare cancers has not been adequately explored in Canada. This analysis aims to characterize the occurrence of rare cancers among Canadians and estimate the probability of being diagnosed with a rare cancer among cancer patients with different demographic characteristics.

METHODS

The Canadian Cancer Registry was used for this analysis. Cancer types were classified in three ways: using the SEER site recode scheme; by histology group; and by site/histology group. The age-standardized incidence rate (ASIR) and 95 % confidence intervals (CI) for each cancer type was estimated for diagnoses from 2006 to 2016. Two ASIR thresholds were used to classify cancers as rare:6/100,000/year and 15/100,000/year. Log-binomial regression was used to estimate the adjusted probability of having a rare cancer among those with cancer by age, sex and geographic region.

RESULTS

Using the 6/100,000/year threshold, the incidence proportion (IP) of rare cancers ranged from 9.7 %(95 %CI:9.6,9.7 %)-17.0 %(95 %CI:16.9,17.0 %), and ranged from 19.2 %(95 %CI:19.1,19.3 %)-52.5 %(95 %CI:52.0,53.0 %) using the <15/100,000/year threshold. The adjusted probability of being diagnosed with a rare cancer was highest among those aged ≤19 years. There was higher concordance in estimates of the burden of rare cancers across methods to classify cancer types when the lower incidence rate threshold was used to define rare cancers.

INTERPRETATION

This analysis yielded evidence that rare cancers comprise a substantial proportion of annual cancer diagnoses among Canadians. Findings from this analysis point to using a lower incidence rate threshold, to generate estimates of the burden of rare cancers that are robust to different cancer classification schemes.

Brain cancer survival in Canada 1996-2008: effects of sociodemographic characteristics

Background

Literature suggests that factors such as rural residence and low socioeconomic status (ses) might contribute to disparities in survival for Canadian cancer patients because of inequities in access to care. However, evidence specific to brain cancer is limited. The present research estimates the effects of rural or urban residence and ses on survival for Canadian patients diagnosed with brain cancer.

Methods

Adults diagnosed with primary malignant brain tumours during 1996-2008 were identified through the Canadian Cancer Registry. Brain tumours were classified using International Classification of Diseases for Oncology (3rd edition) site and histology codes. Hazard ratios (hrs) and 95% confidence intervals (cis) were estimated using Cox proportional hazards models. Events were restricted to individuals whose underlying cause of death was cancer-related. Postal codes were used to match patient records with Statistics Canada data for rural or urban residence and neighbourhood income as a surrogate measure of ses.

Results

Of 25,700 patients included in the analysis, 78% died during the study period, 21% lived in rural areas, and 19% were in the lowest income group. A modest variation in survival by rural compared with urban residence was observed for patients with glioblastoma (first 5 weeks after diagnosis hr: 0.86; 95% ci: 0.79 to 0.99) and oligoastrocytoma (first 3 years after diagnosis hr: 1.41; 95% ci: 1.03 to 1.93). Small effects of low compared with high income were seen for patients with glioblastoma (first 1.5 years after diagnosis hr: 1.15; 95% ci: 1.08 to 1.22) and diffuse astrocytoma (first 6 months after diagnosis hr: 1.17; 95% ci: 1.00 to 1.36).

Conclusions

Our analysis did not yield evidence of strong effects of rural compared with urban residence or ses strata on survival in brain cancer. However, some variation in survival for patients with specific histologies warrants further research into the mechanisms by which rural or urban residence and income stratum influences survival.

Conditional survival after a diagnosis of malignant brain tumour in Canada: 2000-2008

BACKGROUND

"Conditional survival probability" is defined as the probability that a patient will survive an additional time, given that the patient has already survived a defined period of time after diagnosis. Such estimates might be more relevant for clinicians and patients during post-diagnosis care, because survival probability projections are based on the patient's survival to date. Here, we provides the first population-based estimates of conditional survival probabilities by histology for brain cancer in Canada.

METHODS

Canadian Cancer Registry data were accessed for patients diagnosed with primary brain cancers during 2000-2008. Kaplan-Meier survival probabilities were estimated by histology. Conditional survival probabilities at 6 months (short-term, denoted scs) and 2 years (long-term, denoted lcs) were derived from the Kaplan-Meier survival estimates for a range of time periods.

RESULTS

Among the 20,875 patients who met the study criteria, scs increased by a margin of 16-18 percentage points from 6-month survivors to 2-year survivors for the three most aggressive brain cancers. The lcs for 2-year survivors was 66% or greater for all tumour groups except glioblastoma. The lcs for 4-year survivors was 62% or greater for all histologies. For glioblastoma and diffuse astrocytoma, the lcs increased each year after diagnosis. For all other histologies, the lcs first increased and then plateaued from 2 years after diagnosis. The lcs and scs both worsened with increasing older age at diagnosis.

SUMMARY

We report histologically specific conditional survival probabilities that can have value for clinicians practicing in Canada as they plan the course of follow-up for individual patients with brain cancer.

Leukaemia incidence in the Techa River Cohort: 1953-2007

Background:

Little is known about leukaemia risk following chronic radiation exposures at low dose rates. The Techa River Cohort of individuals residing in riverside villages between 1950 and 1961 when releases from the Mayak plutonium production complex contaminated the river allows quantification of leukaemia risks associated with chronic low-dose-rate internal and external exposures.

Methods:

Excess relative risk models described the dose–response relationship between radiation dose on the basis of updated dose estimates and the incidence of haematological malignancies ascertained between 1953 and 2007 among 28 223 cohort members, adjusted for attained age, sex, and other factors.

Results:

Almost half of the 72 leukaemia cases (excluding chronic lymphocytic leukaemia (CLL)) were estimated to be associated with radiation exposure. These data are consistent with a linear dose response with no evidence of modification. The excess relative risk estimate was 0.22 per 100 mGy. There was no evidence of significant dose effect for CLL or other haematopoietic malignancies.

Conclusion:

These analyses demonstrate that radiation exposures, similar to those received by populations exposed as a consequence of nuclear accidents, are associated with long-term dose-related increases in leukaemia risks. Using updated dose estimates, the leukaemia risk per unit dose is about half of that based on previous dosimetry.

Risk of renal cell carcinoma in relation to blood telomere length in a population-based case-control study

Background:

There are few known risk factors for renal cell carcinoma (RCC). Two small hospital-based case–control studies suggested an association between short blood telomere length (TL) and increased RCC risk.

Methods:

We conducted a large population-based case–control study in two metropolitan regions of the United States comparing relative TL in DNA derived from peripheral blood samples from 891 RCC cases and 894 controls. Odds ratios and 95% confidence intervals were estimated using unconditional logistic regression in both unadjusted and adjusted models.

Results:

Median TL was 0.85 for both cases and controls (P=0.40), and no differences in RCC risk by quartiles of TL were observed. Results of analyses stratified by age, sex, race, tumour stage, and time from RCC diagnosis to blood collection were similarly null. In multivariate analyses among controls, increasing age and history of hypertension were associated with shorter TL (P<0.001 and P=0.07, respectively), and African Americans had longer TL than Caucasians (P<0.001).

Conclusion:

These data do not support the hypothesis that blood TL is associated with RCC. This population-based case–control study is, to our knowledge, the largest investigation to date of TL and RCC.

Meat-cooking mutagens and risk of renal cell carcinoma

BACKGROUND

High-temperature cooked meat contains two families of carcinogens, heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Given the kidneys' role in metabolism and urinary excretion of these compounds, we investigated meat-derived mutagens, as well as meat intake and cooking methods, in a population-based case-control study conducted in metropolitan Detroit and Chicago.

METHODS

Newly diagnosed, histologically confirmed adenocarcinoma of the renal parenchyma (renal cell carcinoma (RCC)) cases (n=1192) were frequency matched on age, sex, and race to controls (n=1175). The interviewer-administered Diet History Questionnaire (DHQ) included queries for meat-cooking methods and doneness with photographic aids. Levels of meat mutagens were estimated using the DHQ in conjunction with the CHARRED database.

RESULTS

The risk of RCC increased with intake of barbecued meat (P(trend)=0.04) and the PAH, benzo(a)pyrene (BaP) (multivariable-adjusted odds ratio and 95% confidence interval, highest vs lowest quartile: 1.50 (1.14, 1.95), P(trend)=0.001). With increasing BaP intake, the risk of RCC was more than twofold in African Americans and current smokers (P(interaction)<0.05). We found no association for HCAs or overall meat intake.

CONCLUSION

BaP intake, a PAH in barbecued meat, was positively associated with RCC. These biologically plausible findings advocate further epidemiological investigation into dietary intake of BaP and risk of RCC.

How much can we say about site-specific cancer radiation risks?

Studies of Mayak workers and people who lived along the Techa River have demonstrated significant associations between low-dose-rate radiation exposure and increased solid cancer risk. It is of interest to use the long-term follow-up data from these cohorts to describe radiation effects for specific types of cancer; however, statistical variability in the site-specific risk estimates is large. The goal of this work is to describe this variability and provide Bayesian adjusted risk estimates. We assume that the site-specific estimates can be viewed as a sample from some underlying distribution and use Bayesian methods to produce adjusted excess relative risk per gray estimates in the Mayak and Techa River cohorts. The impact of the adjustment is compared to that seen in similar analyses in the atomic bomb survivors. Site-specific risk estimates in the Mayak and Techa River cohorts have large uncertainties. Unadjusted estimates vary from implausibly large decreases to large increases, with a range that greatly exceeds that found in the A-bomb survivors. The Bayesian adjustment markedly reduced the range of the site-specific estimates for the Techa River and Mayak studies. The extreme variability in the site-specific risk estimates is largely a consequence of the small number of excess cases. The adjusted estimates provide a useful perspective on variation in the actual risks. However, additional work on interpretation of the adjusted estimates, extension of the methods used in describing effect modification, and making more use of prior knowledge is needed to make these methods useful.

Current epidemiological trends and surveillance issues in brain tumors

The absence of an overall increase in incidence rates for all primary brain tumors since the 1950s argues against a recently introduced environmental tumorigen impacting these tumors. Historical increases in brain cancer mortality and incidence rates appear to be leveling off following the widespread introduction of CT and MRI scans, indicating that increases in overall rates of malignant tumors are likely to be an artifact of diagnosis and reporting issues. Further studies are needed to understand those tumor types with rates that do appear to be increasing among adults; specifically lymphomas, nerve sheath tumors, pituitary tumors and ependymomas. Patterns of incidence by race, ethnicity, socioeconomic status, and seasonal and regional variation would assist in directing relevant new research questions. Filling in the gap of information on patterns for prevalent, second primaries and metastatic tumors may be useful in understanding the public perception regarding brain tumor rates and would be a valuable addition to healthcare planning tools.

Prevalence estimates for primary brain tumors in the United States by behavior and major histology groups

Prevalence rates are used to supplement descriptions of disease and are unavailable for all primary brain tumors in the United States. Data from two population-based tumor registries were obtained from the Central Brain Tumor Registry of the United States and used to compute age-specific incidence rates (1985-1994) and survival curves for further use in a statistical model to estimate prevalence rates. Prevalence rates were then used to estimate the number of individuals living with a brain tumor diagnosis in the U.S. population for the year 2000. The overall incidence rate in these regions is 13.8 per 100,000 with 2-, 5-, and 10-year survival rates of 58%, 49%, and 38%, respectively. The prevalence rate for all primary brain tumors is 130.8 per 100,000 with approximately 350,000 individuals estimated to be living with this diagnosis in the United States in 2000. The prevalence rate for malignant tumors, 29.5 per 100,000, is similar to previous reports. The prevalence rate for benign tumors, 97.5 per 100,000, is new. Unlike incidence data, the proportion (and expected number) of existing benign tumors (75%, 267,000) is considerably greater than that for malignant tumors (23%, 81,000), reflecting the better prognosis of benign tumors diagnosed in individuals younger than 60 years old. These data underscore the impact of primary brain tumors in the U.S. health care system and emphasize the need for quality-of-life considerations, particularly for those long-term survivors of benign tumors.

Trends in incidence of primary brain tumors in the United States, 1985-1994

Brain tumor incidence has increased over the last 20 years in all age groups, both overall and for specific histologies. Reasons attributed to these increases include increase in lymphoma due to HIV/AIDS, introduction of computed tomography/magnetic resonance imaging, and changes in coding/classification. The purpose of this study was to describe overall and histologic-specific incidence trends in a population-based series of primary benign and malignant brain tumors. Data from the Central Brain Tumor Registry of the United States from 1985 through 1994 were used to determine incidence trends in the broad age groups 0-19, 20-64, and > or = 65 years, both overall and for selected histologies. Poisson regression was used to express trends as average annual percentage change. Overall, incidence increased modestly (annual percentage change 0.9%, 95% confidence interval, 0.4, 1.4). When lymphomas were excluded, this result was not statistically significant (annual percentage change 0.5%, 95% confidence interval, -0.1, 1.1). Specific histologies that were increasing were lymphomas in individuals aged 20 to 64 years and in males aged 65 years or older, ependymomas in the population aged 20 to 64 years, nerve sheath tumors in males, and pituitary tumors in females. Increases that were not specific to any population subgroup were seen for glioblastoma, oligodendrogliomas, and astrocytomas, excluding not otherwise specified (NOS) tumors. Corresponding decreases were noted for NOS, astrocytoma NOS, and glioma NOS. Increasing incidence trends for lymphomas were consistent with previous literature. Improvements in diagnostic technology in addition to changes in classification and coding were likely to be responsible for decreases seen in incidence of NOS subgroups and corresponding increases in glioma subgroups. In contrast, the increases identified for ependymomas, nerve sheath tumors, and pituitary tumors were less likely to be artifacts of improvements in diagnosis, and they warrant further study.

Epidemiology of brain tumors

Primary brain tumor incidence and survival patterns are emerging, assisted by progress in molecular classification. Evidence is accumulating to suggest that infectious diseases may affect the risk of developing a brain tumor, although data require clarification. Other promising research directions include evaluating the role of diet and allergic conditions in reducing brain tumor risk.

The descriptive epidemiology of brain tumors

Brain tumors have been the subject of controversy both with respect to patterns of occurrence and to potential causes. This article provides a description of current data resources on brain tumors and outlines issues affecting the interpretation of population-based data. A template for estimating regional expected values for brain tumors is provided, and current patterns of incidence, survival, and conditional survival are described. The occurrence of second primary tumors and quality of life studies are also reviewed.

Centralized databases available for describing primary brain tumor incidence, survival, and treatment: Central Brain Tumor Registry of the United States; Surveillance, Epidemiology, and End Results; and National Cancer Data Base

Characteristics of three databases--the Central Brain Tumor Registry of the United States (CBTRUS) database; the Surveillance, Epidemiology and End Results (SEER) database; and the National Cancer Data Base (NCDB)--containing information on primary brain tumors are discussed. The recently developed population-based CBTRUS database comprises incidence data on all primary brain tumors from 11 collaborating state registries; however, follow-up data are not available. SEER, the population-based gold standard for cancer data, collects incidence and follow-up data on malignant brain tumors only. While not population-based, the NCDB identifies newly diagnosed cases and conducts follow-up on all primary brain tumors from hospitals accredited by the American College of Surgeons. The NCDB is the largest of the three databases and also contains more complete information regarding treatment of these tumors than either the SEER or CBTRUS databases. Additional strengths and limitations of each of these are described, and their judicious use for supporting research, education, and health care planning is encouraged.

The contribution of nonmalignant tumors to CNS tumor incidence rates among children in the United States

OBJECTIVES

According the U.S. National Cancer Institute (NCI), the incidence rate of primary malignant central nervous system (CNS) neoplasms among children is about 30 per million person-years. This rate, however, underestimates the true burden of CNS tumors because nonmalignancies are not included in the NCI case reporting system. Intracranial tumors, to an extent regardless of their histological behavior, can have a malignant clinical course and result in a high degree of morbidity and mortality. The purpose of this report is to estimate the contribution that nonmalignant tumors have on the overall incidence of CNS tumors in children.

METHODS

Population-based data from the Central Brain Tumor Registry of the United States were analyzed. Included in the analysis were children aged 0-19 years who were diagnosed with a primary CNS tumor from 1990-93 (N = 1133).

RESULTS

The inclusion of nonmalignancies increased the CNS tumor incidence rate by 28% from 29.4 to 37.6 per million person-years. The increases were 17% for children aged 0-4 years, 17% for children aged 5-9 years, 31% for children aged 10-14 years and 57% for adolescents aged 15-19 years. Differences in patterns between malignant and nonmalignant tumor occurrence by sex, histology, and location were also observed.

CONCLUSION

Because of the potentially profound adverse health effects on children who experience CNS tumors, the systematic collection of both malignancies and nonmalignancies is consistent with the mission of public health surveillance. Without such population-based data, analytic epidemiologic studies to evaluate disease etiology and assess disease consequences are greatly hindered.

The conditional probability of survival of patients with primary malignant brain tumors: surveillance, epidemiology, and end results (SEER) data

BACKGROUND

Five-year survival estimates in standard cancer reports provide a general description of disease outcome that is useful for surveillance and comparison purposes. However, for cancer survivors these overall survival rates may be discouraging, and the relevant question regarding an individual is this: Once he or she has survived for a specified period of time, what is the probability of survival over the next period of time?

METHODS

To address this, conditional survival rates by histology for malignant brain tumor survivors were estimated using the SEER public use data and the Portable Survival System, with 19,105 brain and other nervous system patients diagnosed between 1979 and 1993. Given that the survival curve declines more rapidly in the first 2 years than in subsequent years, conditional probabilities of surviving 5 years given survival to 2 years and 95% confidence intervals (CIs)were calculated. As age is a strong prognostic factor for these tumors, conditional probabilities were also estimated by categories of age.

RESULTS

Estimated 2- and 5-year relative survival rates for patients with malignant brain and other CNS tumors were 36.2% and 27.6%; however, the conditional probability of surviving to 5 years, given survival to 2 years, reaches 76.2% (95% CI: 74.8-77.6). Conditional probabilities varied by histology and age at diagnosis. The conditional probability of surviving 5 years after surviving 2 years was 67.8% (95% CI: 62.6-73.1) for patients with anaplastic astrocytomas, 36.4% (95% CI: 31.9-41.6) for patients with glioblastomas, and 79.8% (95% CI:75.3-84.1) for patients with medulloblastomas.

CONCLUSIONS

Conditional probabilities provide important and encouraging information for those who are brain tumor survivors. The utility of these estimates for other time intervals and other cancers or diseases should be considered.

Descriptive epidemiology of primary brain and CNS tumors: results from the Central Brain Tumor Registry of the United States, 1990-1994

The Central Brain Tumor Registry of the United States (CBTRUS) obtained 5 years of incidence data (1990-1994)--including reports on all primary brain and CNS tumors--from 11 collaborating state cancer registries. Data were available for 20,765 tumors located in the brain, meninges, and other CNS sites, including the pituitary and pineal glands. The average annual incidence was estimated at 11.5 cases per 100,000 person-years. The higher incidence of tumors in male patients (12.1 per 100,000 person-years) than in female patients (11.0 per 100,000 person-years) was statistically significant (P < 0.05); the higher incidence in whites (11.6 per 100,000 person-years) compared with blacks (7.8 per 100,000 person-years) was statistically significant (P < 0.05). The most frequently reported histologies were meningiomas (24.0%) and glioblastomas (22.6%). Higher rates for glioblastomas, anaplastic astrocytomas, oligodendrogliomas, anaplastic oligodendrogliomas, ependymomas, mixed gliomas, astrocytomas not otherwise specified, medulloblastomas, lymphomas, and germ cell tumors in male than in female patients were statistically significant (P < 0.05), with relative risks (RR) ranging from 1.3 to 3.4. Meningiomas were the only tumors with a significant excess in females (RR = 0.5). We noted higher occurrence rates in whites than in blacks for the following histologies: diffuse astrocytomas, anaplastic astrocytomas, glioblastomas, oligodendrogliomas, ependymomas, mixed gliomas, astrocytomas NOS, medulloblastomas, nerve sheath tumors, hemangioblastomas, and germ cell tumors, with RRs ranging from 1.5 to 3.4. Racial differences in occurrence rates were not observed for predominately benign meningiomas or pituitary tumors. This study represents the largest compilation of data on primary brain and CNS tumors in the United States. Standard reporting definitions and practices must be universally adopted to improve the quality and use of cancer registry data.

Factors associated with survival in patients with meningioma

OBJECT

To explore factors affecting the survival rate in patients with meningiomas, the authors used the National Cancer Data Base (NCDB), which includes tumors from approximately 1000 hospitals participating in the American College of Surgeons tumor registry program.

METHODS

Analysis included over 9000 cases diagnosed from 1985 to 1988 and 1990 to 1992. Survival estimates were computed and prognostic factors were identified using a proportional hazards model. The overall 5-year survival rate was 69% and it declined with patient age. This rate was 81% in patients aged 21 to 64 years and 56% for patients 65 years of age or older. When patients were grouped by the histological type of their tumors, those with benign tumors had an overall 5-year survival rate of 70%, whereas the overall 5-year survival rates in patients with atypical and malignant meningiomas were 75% and 55%, respectively. Prognostic factors for benign tumors included age at diagnosis, tumor size, whether treated surgically, hospital type, and radiation therapy; for malignant tumors, the prognostic factors included: age at diagnosis, whether treated surgically, and radiation therapy. These factors were statistically significant. The 5-year rate for recurrence of symptoms (regardless of the method of treatment) was 19.2% for those with benign tumors and 32.4% for those with malignant tumors. In patients whose benign tumor had been completely removed, the 5-year rate of tumor recurrence was 20.5%.

CONCLUSIONS

Although not population-based, the NCDB has the potential for providing pertinent information regarding patient characteristics and methods of treatment for benign, as well as malignant, brain tumors.

The rationale for standardized registration and reporting of brain and central nervous system tumors in population-based cancer registries

Most population-based statistical reports of brain and central nervous system (CNS) tumors are limited to data of primary malignant tumors and to summary estimates of all tumor locations and histologies. We argue that data of benign brain and CNS tumors should also be included in registry reports and that standard definitions for the reporting of all brain and CNS tumors by site and histology should exist. We demonstrate current inconsistencies in the definitions of brain and CNS tumor sites used in reports. Grouping of brain and CNS tumors by subtype--which integrates the current World Health Organization classification scheme with the International Classification of Diseases for Oncology coding system used in cancer registries--is proposed. Adoption of standard tumor site and behavior codes for annual reports would aid the comparison of rates of brain and CNS tumors between geographic regions, allow for the evaluation of trends over time, and provide new estimates of tumor subtypes in a more clinically relevant format. A consensus among cancer registries and neuroscientists is needed to adopt standard definitions so that accurate and clinically relevant brain and CNS tumor data are available.

Survival rates in patients with primary malignant brain tumors stratified by patient age and tumor histological type: an analysis based on Surveillance, Epidemiology, and End Results (SEER) data, 1973-1991

OBJECT

The authors present population-based survival rate estimates for patients with malignant primary brain tumors based on an analysis of 18 years of data obtained from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute.

METHODS

Estimates of survival rates at 2 and 5 years after diagnosis for patients with specific histological tumor types were categorized by patient's age at diagnosis (< or = 20 years, 21-64 years, and 65 years or older) and by the time period in which the patients were diagnosed (1973-1980, 1981-1985, 1986-1991). Where appropriate, survival estimates were adjusted for changing patterns in the mean age at diagnosis.

CONCLUSIONS

The authors observed a pattern of declining survival rates in patients with increasing age of the patient at diagnosis for most histological groups and overall improvements in survival rates of patients across these time periods adjusting for age at diagnosis. There were improvements in 2- and 5-year survival rates over the three time periods for children and adults with medulloblastoma and for adults with astrocytoma and oligodendroglioma. Improvements in survival rates for pediatric patients with medulloblastoma have leveled off in the most recent time period, and gender differences in survival rates for patients with this tumor, which were present in the 1970s, have disappeared. Clinically significant improvements in survival rates were not apparent in patients aged 65 years and older. Changes in diagnostic and treatment procedures since the mid-1970s have resulted in improved survival rates for patients diagnosed as having medulloblastoma, oligodendroglioma, and astrocytoma, controlling for age at diagnosis. Glioblastoma multiforme continues to be the most intractable brain tumor.

Primary brain tumor incidence rates in four United States regions, 1985-1989: a pilot study

There has been controversy in the last decade over whether the reported increase in brain tumors reflects a real increase in incidence rates. Incidence data on the full spectrum of brain tumors is lacking in the discussion since current cancer reports in the United States are restricted to malignant tumors. Data on tumors from four population-based cancer registries in the United States were compiled to provide incidence rates of benign and malignant brain tumors and to assess the feasibility of providing these data on a larger scale. A total of 8,070 primary tumors diagnosed from 1985 to 1989 in Connecticut, Massachusetts, Missouri and Utah were obtained. Brain tumors were defined using the International Classification of Diseases for Oncology codes 191.0-191.9, 192.0-192.3, 192.8-192.9 and 194.3-194.4. Stratum-specific incidence rates by location and histology were estimated by sex, age and region. Age-adjusted rates were standardized to the 1970 United States population. An age-adjusted incidence rate of 9.4/10(5) was observed, which reflects a 36% increase in males and a 68% increase in females over the rate based on malignant tumors alone from the Surveillance, Epidemiology and End Results cancer reporting system. Incorporating benign tumors into cancer registry data would increase the reported incidence rates primarily in females and for meningiomas and nerve sheath tumors. This expanded incidence rate represents a substantial improvement in the ability to describe the occurrence of these complex tumors by subtype with a modest increase in overall case registrations for cancer registries. Centralization of data on all brain tumors appears feasible. Variations in histology-specific rates across regions raises questions that need to be addressed about the ascertainment and accuracy of tumor classification. Use of the cancer registration system to improve the reporting of brain tumors in the United States is important to our understanding of the occurrence of these complex tumors and to our ability to conduct large-scale epidemiologic investigations.

Serum selenium and colonic neoplastic risk

BACKGROUND

Selenium deficiency has been associated with cancer risk in several organs. This association was investigated in neoplasia of the colorectum.

DESIGN

A case-control study is reported with two patient series, colorectal cancer and colorectal adenomatous polyps, and a control group found to be free of colorectal neoplasia. Diagnosis was determined by colonoscopy and histologic review of suspected neoplasms. Serum drawn at the time of colonoscopy was subsequently assayed for selenium content, and quartiles based on selenium were defined. Crude and adjusted odds ratios with 95 percent confidence intervals for adenoma related to selenium were calculated, controlling for known or suspected risk factors including gender, age, race, body mass index, family history, tobacco use, alcohol consumption, serum beta carotene, serum alpha tocopherol, and serum ferritin.

RESULTS

There were 138 controls who had no neoplastic disease, 139 adenoma patients, and 25 cancer patients. For adenoma, comparing higher quartiles of selenium to the first (lowest selenium), the adjusted odds ratio for the second quartile was 1.7 (95 percent confidence interval, 0.8-3.7), the third quartile was 1.4 (0.7-3.2), and the fourth (highest selenium) quartile was 1.8 (0.9-4). The odds ratios for cancer patients were 0.8 for the second quartile, 1 for the third quartile, and 1.7 for the fourth quartile.

CONCLUSION

No trend could be detected toward a protective effect of higher levels of serum selenium for colonic benign or malignant tumors.

Risk of neoplastic and other diseases among people with heterozygosity for hereditary hemochromatosis

BACKGROUND

Increased body iron stores have been associated with risk of heart attack in men and risk of cancer and colonic adenoma in both sexes. Because heterozygous carriers of hereditary hemochromatosis (HH) have on the average increased iron stores compared with noncarriers of the HH gene and comprise as much as 15% of the American population, disease risk in HH heterozygotes was investigated.

METHODS

A community-based cohort was defined, in which the exposure variable was heterozygosity for HH. Heterozygotes were identified by mailing individuals homozygous for HH questionnaires concerning the health histories of their parents (predominantly heterozygotes or exposed). Spouses of the HH homozygotes were asked to complete accompanying questionnaires concerning their parents (unexposed). The frequencies for exposed and unexposed, age-adjusted relative risks (RR), and 95% confidence intervals (CI), of cancer, heart disease, and stroke as causes of death as well as the cumulative incidence of heart attack, diabetes, stroke, hypertension, colonic adenoma, and cancers of the lung, colorectum, breast, cervix, pancreas, stomach, and blood were estimated.

RESULTS

Data were available for 1950 HH heterozygotes and 1656 unexposed subjects. Elevated RR were observed in HH heterozygotes in males for diabetes (RR, 1.16; 95% CI, 1.01-1.33), colorectal cancer (RR, 1.28; CI, 1.07-1.53), and hematologic malignancy (RR, 1.30; CI, 1.30-1.63), for colonic adenoma in females (RR, 1.29; CI, 1.08-1.53) and males (RR, 1.24; CI, 1.05-1.46), and for stomach cancer in females (RR, 1.37; CI, 1.04-1.79).

CONCLUSIONS

Heterozygosity for HH is associated with increased risk for colorectal neoplasia, diabetes, hematologic malignancy, and gastric cancer. No increased risk of heart disease, cancer death, or cancers of the lung, breast, or cervix were demonstrated.

Cancer incidence of Hispanics and non-Hispanic whites in Cook County, Illinois

BACKGROUND

Variations in cancer incidence and mortality rates between Hispanics and non-Hispanic whites have been reported in several regions in the United States. This report describes the ethnic variation in selected cancer sites in Cook County, Illinois.

METHODS

Cancer incidence, age-specific, and age-standardized relative rates, and 95% confidence intervals were estimated among Hispanics and non-Hispanic whites in Cook County, Illinois, for 1986-1987. Hispanics were identified using surnames and maiden names with the Generally Useful Ethnic Search System (GUESS).

RESULTS

Rates of lung cancer in Hispanics were approximately half of those observed for non-Hispanic whites. Hispanics also had lower rates of colon, breast, and bladder cancer. Hispanic females had rates of invasive cervical cancer that were approximately two times higher than those of non-Hispanic whites.

CONCLUSIONS

These results are consistent with previous studies and suggest that Hispanics residing in the United States may retain some of the risk profile of those living in their home country.

Incidence of second cancers in patients treated for Hodgkin's disease

BACKGROUND

Numerous studies of treatment for Hodgkin's disease have demonstrated large increases in the incidence of leukemia in the early years following chemotherapy, although the duration of effect and the specific agents involved are not well understood. Also, some, but not all, studies have indicated that the incidence of certain solid tumors increases following treatment for Hodgkin's disease.

PURPOSE

We studied the association between treatment for Hodgkin's disease and the incidence of second cancers.

METHODS

We conducted a study within a cohort that included 10,472 patients from 14 cancer centers in the United States and Canada who were first diagnosed as having Hodgkin's disease at some point from 1940 through 1987. Discounting the 1st year after diagnosis, the average length of follow-up was 7.1 years per subject.

RESULTS

We observed 122 leukemias and 438 solid tumors. The relative risk (RR) of leukemia following chemotherapy, compared with no chemotherapy, was 14 (95% confidence interval [CI] = 5.6-35). Increased risks of leukemia were observed after treatment with chlorambucil (RR = 2.0; 95% CI = 1.1-3.6), procarbazine (RR = 4.9; 95% CI = 2.6-9.1), vinblastine (RR = 1.7; 95% CI = 1.1-2.8), and a group of rarely used drugs that included methotrexate, vindesine, etoposide, and 22 others (RR = 3.8; 95% CI = 1.9-7.4). RRs were also estimated for various combinations of drugs, including MOPP (mechlorethamine, vincristine, procarbazine, and prednisone) (RR = 5.9; 95% CI = 2.9-12) and ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) (RR = 1.5; 95% CI = 0.7-3.4). The RR of leukemia associated with splenectomy was 1.6 (95% CI = 1.0-2.5). The RR of solid tumors following chemotherapy was 1.4 (95% CI = 1.1-1.8). For the group of rarely used drugs, the RR of solid tumors was 3.1 (95% CI = 1.7-5.8). Chemotherapy was associated with an increased risk of cancers of the bones, joints, articular cartilage, and soft tissues (RR = 6.0; 95% CI = 1.7-20), and cancers of the female genital system (RR = 1.8; 95% CI = 1.1-3.2). In patients followed for 10 or more years after radiotherapy, increased risks were found for cancers of the respiratory system and intrathoracic organs (RR = 2.7; 95% CI = 1.1-6.8) and for cancers of the female genital system (RR = 2.4; 95% CI = 1.1-5.4).

CONCLUSIONS

Procarbazine, chlorambucil, and vinblastine are associated with increased leukemia risk. Combination drug regimens have leukemogenic effects estimated as the product of RRs for individual drugs. Chemotherapy and radiotherapy increase the risk of selected solid tumors, and the effect of chemotherapy on solid tumor risk is weaker than the leukemogenic effect.

IMPLICATIONS

Without doubt, the benefits of treatment of Hodgkin's disease outweigh the risk of a subsequent malignancy, but data on the carcinogenic effects of radiation and drugs beyond 10 years after treatment continue to be sparse, and future analyses should be directed at long-term survivors.

Prevalence of benign anorectal disease in a randomly selected population

BACKGROUND

The prevalence of benign anorectal diseases (BAD) in the general population has been difficult to establish, either because the individual diseases themselves were difficult to characterize in surveys or because of bias in the selection of the survey population. Reported herein is a prevalence survey of BAD symptoms and treatment history of a sample of the general population, selected by random digit dialing.

METHOD

A survey instrument that inquired into symptoms of BAD, BAD treatment history, and health-seeking behaviors was administered by telephone interview with 102 individuals, between the ages of 21 and 65 of both genders and all races, chosen by random digit dialing in the Joliet, Illinois area. For selected variables (gender, education level, obesity, previous BAD treatment, fiber supplementation, time for defecation and reading during defecation all related to BAD symptoms) odds ratios and 95 percent confidence intervals were calculated.

RESULTS

Of the 102 individuals, 9 had been previously treated for hemorrhoids, 4 by surgery, and 5 medically. Twenty individuals currently have BAD symptoms, six of these have multiple symptoms frequently, implying established BAD, and four of these have been previously treated for hemorrhoids. Seven of eight individuals with rectal bleeding in the past year have not sought medical evaluation. Of the associations tested, statistical significance was found only between female gender and BAD symptoms (odds ratio = 4.6; 95 percent confidence interval = 1.3-20.4).

CONCLUSIONS

History of hemorrhoidal treatment and current BAD symptomatology are highly prevalent in a randomly selected population, and 80 percent of the subjects with symptoms of BAD have not consulted a physician regarding BAD. Some previously held correlates of hemorrhoidal symptoms, such as obesity and extended time for defecation, showed no apparent association with hemorrhoid treatment history or current BAD symptoms. The best predictors of current BAD symptoms were female gender (odds ratio = 4.6; 95 percent confidence interval = 1.3-20.4) and previous hemorrhoid treatment (odds ratio = 3.9; 95 percent confidence interval = 0.7-20).

Replacement of entire aorta from aortic valve to bifurcation during one operation

A 68-year-old patient presented with an extensive aortic aneurysm extending from the aortic valve to the aortic bifurcation associated with severe continuous pain, dysphagia, and hoarseness. Because of the risk of impending rupture and an "elephant trunk" procedure not being an option, the entire aorta from the aortic valve to the aortic bifurcation was replaced during one operation using deep hypothermia with circulatory arrest and retrograde perfusion of the brain through the jugular veins. Seven months after the operation the patient walks more than 3 km a day and lives a normal life. The operative repair is presented.

Body iron stores and risk of colonic neoplasia

BACKGROUND

Body iron stores and dietary iron intake have both been shown to be positively associated with subsequent risk of colon cancer. This finding comes from a cohort study involving 14,000 men, but the positive association occurred in only 12 cases.

PURPOSE

We performed a case-control study of 264 men and 98 women to test for an association between serum ferritin levels and the presence of adenoma of the colon that would be independent of other known risk factors.

METHODS

Serum ferritin levels were determined in this study from sera, frozen at -80 degrees C for 5-8 years, that had been originally obtained between 1984-1987 at the Walter Reed Army Medical Center from adult male and postmenopausal female patients undergoing routine colonoscopic examination and previously enrolled in a case-control study that assessed the potential dietary and environmental risk factors for colonic neoplasia. The presence of fecal occult blood in the stool or the suggestion of colonic polyps seen on barium enema defined eligibility for the study. Patients with known preexisting colonic disease were excluded. Eligible patients had their blood drawn and serum prepared. Following colonoscopy and histologic review, the patients were classified into three groups: normal (without neoplastic disease), 159 subjects; adenoma, 145 subjects; and colon cancer, 29 subjects. Body iron stores were determined by measuring serum ferritin levels by a competitive-binding radiometric immunoassay. Ferritin levels categorized into quintiles for adenoma were defined. Crude and adjusted odds ratios (ORadj) with 95% confidence intervals (CIs) for cancer and adenoma related to ferritin were calculated, controlling for known or suspected risk factors including sex, age, race, body mass index, family history, tobacco use, and alcohol consumption.

RESULTS

Statistically significant associations of adenoma risk were seen in the third ([ORadj] = 3.8; 95% CI = 1.5-9.5) and fourth (ORadj = 5.1; 95% CI = 2.0-12.7) quintiles of ferritin relative to the first quintile, for smoking history (ORadj = 2.4; 95% CI = 1.3-4.3), for male sex (ORadj = 1.9; 95% CI = 1.0-3.7), and for family history of polyps or cancer (ORadj = 1.8; 95% CI = 1.0-3.4). From a second set of analyses that excluded 36 patients with serum ferritin of greater than or equal to 399 ng/mL, the greatest effect of ferritin on adenoma risk by anatomic subsite was seen in the right colon.

CONCLUSION

The apparent dose-response for serum ferritin level and adenoma risk suggest that exposure to iron may be related to adenoma formation.

The relationship between exposure during pregnancy to cigarette smoking and cocaine use and placenta previa

OBJECTIVE

This study examined the relationship between two maternal exposures, cigarette smoking and cocaine use, and placenta previa.

STUDY DESIGN

A hospital-based case-control study was conducted. Three hundred four cases of placenta previa were compared with 2732 controls with respect to demographic characteristics, substance use, and perinatal characteristics. Logistic regression was used to examine the individual effects of cigarette smoking and cocaine use on placenta previa, independent of other known risk factors.

RESULTS

A dose-response relationship between smoking cigarettes and placenta previa was observed independent of other known risk factors (ptrend < 0.01). Pregnant women who smoked > or = 20 cigarettes per day were over two times more likely to experience a placenta previa relative to nonsmokers (odds ratio 2.3, 95% confidence interval 1.5 to 3.5). Pregnant women who used cocaine were 1.4 times (95% confidence interval 0.8 to 2.4) as likely to experience a placenta previa as nonusers.

CONCLUSIONS

The previously observed association between smoking and placenta previa is supported by the dose-response relationship observed in this study. The potential association of cocaine with placenta previa needs more exploration.

Self-reported dietary changes with respect to American Cancer Society nutrition guidelines (1982-1986)

A follow-up study was conducted by the Illinois Division of the American Cancer Society (ACS) in conjunction with the ongoing National Cancer Prevention Study II (CPSII) to determine whether self-report dietary changes are occurring in accordance with the ACS nutrition guidelines and to identify demographic subgroups that may be targeted for future prevention and education programs. A total of 42,300 CPSII respondents completed a 1986 questionnaire and were matched to 1982 baseline data. Dietary items were recorded as "on the average, how many days per week do you eat the following foods?" Individuals with known chronic conditions, body mass index outside a moderate range, and fewer than four completed food items were excluded. The remaining study population (n = 18,062) included men and women who were apparently healthy and primarily over the age of 50. The distribution of foods reported in 1982 and changes in foods consumed (1982-1986) among selected food groups varied modestly by sex, age, and educational level. Modest changes in the direction of decreasing intake of high-fat foods and increasing intake of high-fiber foods and cruciferous vegetables were reported. Dietary changes consistent with the ACS nutrition guidelines appear to have taken place in this population, particularly for the use of fried foods in males and intake of high-fiber foods and cruciferous vegetables in females.

Undernutrition as a risk factor for cervical intraepithelial neoplasia: a case-control analysis

To evaluate the relationship between cervical intraepithelial neoplasia (CIN) and undernutrition, a pair-matched case-control study was conducted in a low-income urban population. As a broad measure of nutritional status, serum albumin, serum ferritin, hematocrit, percent desirable weight, and percent calories consumed as protein were examined. Cases (n = 102) had biopsy-confirmed CIN I, II, or III, and clinic controls (n = 102), matched on age, race, and clinic, had normal Pap smears. Survey-collected data and frozen serum were utilized to study the hypothesized association. Crude and adjusted odds ratios and 95% confidence intervals were estimated using conditional logistic regressions. Results suggest a protective role for serum ferritin for those in the highest quartile relative to those in the lowest quartile. Controlling for smoking and monthly personal income, an adjusted odds ratio of 0.2 with a corresponding 95% confidence interval of 0.1-0.7 was observed. Similar findings were noted when all other available CIN risk factors were controlled. In addition, a dose gradient was present for dietary iron intake (p = 0.01). No associations were observed between each of the other undernutrition indexes and CIN. Although only high levels of serum ferritin were associated with a protective effect against CIN, when coupled with the results from other studies that suggest carotenoids, folates, and vitamin C to be protective, the overall hypothesis that poor nutriture is associated with CIN remains viable. Lack of an association with the other nutritional indexes may reflect the relatively sufficient nutritional status of low-income individuals residing in the United States, as opposed to the undernourished population of the Third World.

Folate, vitamin C, and cervical intraepithelial neoplasia

A case-control study was designed to assess the relationship between cervical intraepithelial neoplasia (CIN) and folate in serum, red blood cells, and diet. The association between CIN and dietary vitamin C was also investigated. Cases were selected from women with biopsy-confirmed CIN. Controls were age-, race-, and clinic-matched women with normal cervical (Pap) smears. Study participants completed self-administered food frequency (n = 100 matched pairs) and health (n = 102 matched pairs) questionnaires. Fasting venous blood samples were collected for serum (n = 98 matched pairs) and red cell (n = 68 matched pairs) folate assays. Conditional logistic regression models were used to estimate crude odds ratios and odds ratios adjusted for smoking, income, number of sexual partners, frequency of cervical smear, use of spermicidal contraceptive agents, history of genital warts, and Quetelet index. Dietary intake variables were adjusted for total energy intake prior to logistic regression. A protective effect of red cell folate was evident with adjusted odds ratios (95% confidence intervals) of 0.1 (0.0-0.4), 0.6 (0.2-2.0), and 0.5 (0.2-1.9) for those in quartiles 4 (highest), 3, and 2 compared to quartile 1 (lowest). Supporting evidence for the protective effect of folate was provided by inverse associations between CIN and folate in both serum and diet. An inverse association was also found between CIN and dietary vitamin C with adjusted odds ratios (95% confidence intervals) of 0.2 (0.0-0.7), 0.6 (0.2-1.6), and 0.6 (0.2-1.8) for those in quartiles 4, 3, and 2, respectively, compared to quartile 1. These findings support dietary recommendations, such as those of the American Cancer Society, the National Cancer Institute, and the U.S. Dietary Guidelines, which allow for adequate intake of folate and vitamin C, both of which are found in good quantity in fruits and vegetables. Increased consumption of legumes and whole grains is also in accord with current dietary recommendations, and both of these types of foods are good sources of folates.

Perioperative complications of anesthesia

An overview of several perioperative complications and their management strategies is presented. Operative hypothermia, malignant hyperthermia, bronchospasm, and side effects of spinal opioid agents are discussed. Ramifications of these complications may extend well beyond the operative period and influence patient outcome. Therefore, it is necessary that the surgeon have a fundamental understanding of the pathophysiology and modalities of treatment in the context of anesthesia and surgery.

Dietary and serum carotenoids and cervical intraepithelial neoplasia

A case-control study examined the association between cervical intra-epithelial neoplasia (CIN) and serum and dietary alpha-carotene, beta-carotene, cryptoxanthin, lutein, and lycopene. Cases (n = 102) had biopsy confirmed CIN I, II or III. Controls matched for age, ethnic origin and clinic (n = 102) had normal Pap smears. Participants completed health history and food frequency questionnaires. Fasting venous blood samples were assayed for serum carotenoids. Multivariable conditional logistic regression analyses yielded odds ratios and 95% confidence intervals (CIs) for those in quartiles 3, 2, and 1 (lowest) compared to quartile 4 (highest) of serum lycopene of 3.5 (1.1-11.5), 4.7 (1.2-17.7) and 3.8 (1.1-12.4), respectively. Similar analyses yielded adjusted odds ratios (ORaS) and 95% CIs of 4.6 (1.1-19.7), 5.8 (1.6-21.3) and 5.4 (1.3-23.3) for dietary intake of lycopene. The findings for lycopene-rich foods (tomatoes) were consistent with this result. CIN was not associated with the lutein. Findings for alpha-carotene, beta-carotene and cryptoxanthin were ambiguous. Quartile of vitamin C intake was also inversely associated with CIN with ORaS and 95% CIs of 3.7 (0.9-14.6), 4.1 (1.0-17.2), and 6.4 (1.4-30.0) for those in quartiles 3, 2, and 1 compared to quartile 4.

Frequent chest X-ray fluoroscopy and breast cancer incidence among tuberculosis patients in Massachusetts

The incidence of breast cancer was determined in 4940 women treated for tuberculosis between 1925 and 1954 in Massachusetts. Among 2573 women examined by X-ray fluoroscopy an average of 88 times during lung collapse therapy and followed for an average of 30 years, 147 breast cancers occurred in contrast to 113.6 expected [observed/expected (O/E) = 1.29; 95% confidence interval (CI) = 1.1-1.5]. No excess of breast cancer was seen among 2367 women treated by other means: 87 observed versus 100.9 expected. Increased rates for breast cancer were not apparent until about 10 to 15 years after the initial fluoroscopy examination. Excess risk then remained high throughout all intervals of follow-up, up to 50 years after first exposure. Age at exposure strongly influenced the risk of radiation-induced breast cancer with young women being at highest risk and those over age 40 being at lowest risk [relative risk (RR) = 1.06]. Mean radiation dose to the breast was estimated to be 79 cGy, and there was strong evidence for a linear relationship between dose and breast cancer risk. Allowing for a 10-year minimum latent period, the relative risk at 1 Gy was estimated as 1.61 and the absolute excess as 10.7 per 10(4) woman-years per gray. When compared to other studies, our data suggest that the breast is one of the most sensitive tissues to the carcinogenic force of radiation, that fractionated exposures are similar to single exposures of the same total dose in their ability to induce breast cancer, that risk remains high for many years after exposure, and that young women are especially vulnerable to radiation injury.

Cancer mortality following radium treatment for uterine bleeding

Cancer mortality in relation to radiation dose was evaluated among 4153 women treated with intrauterine radium (226Ra) capsules for benign gynecologic bleeding disorders between 1925 and 1965. Average follow up was 26.5 years (maximum = 59.9 years). Overall, 2763 deaths were observed versus 2687 expected based on U.S. mortality rates [standardized mortality ratio (SMR) = 1.03]. Deaths due to cancer, however, were increased (SMR = 1.30), especially cancers of organs close to the radiation source. For organs receiving greater than 5 Gy, excess mortality of 100 to 110% was noted for cancers of the uterus and bladder 10 or more years following irradiation, while a deficit was seen for cancer of the cervix, one of the few malignancies not previously shown to be caused by ionizing radiation. Part of the excess of uterine cancer, however, may have been due to the underlying gynecologic disorders being treated. Among cancers of organs receiving average or local doses of 1 to 4 Gy, excesses of 30 to 100% were found for leukemia and cancers of the colon and genital organs other than uterus; no excess was seen for rectal or bone cancer. Among organs typically receiving 0.1 to 0.3 Gy, a deficit was recorded for cancers of the liver, gall bladder, and bile ducts combined, death due to stomach cancer occurred at close to the expected rate, a 30% excess was noted for kidney cancer (based on eight deaths), and there was a 60% excess of pancreatic cancer among 10-year survivors, but little evidence of dose-response. Estimates of the excess relative risk per Gray were 0.006 for uterus, 0.4 for other genital organs, 0.5 for colon, 0.2 for bladder, and 1.9 for leukemia. Contrary to findings for other populations treated by pelvic irradiation, a deficit of breast cancer was not observed (SMR = 1.0). Dose to the ovaries (median, 2.3 Gy) may have been insufficient to protect against breast cancer. For organs receiving greater than 1 Gy, cancer mortality remained elevated for more than 30 years, supporting the notion that radiation damage persists for many years after exposure.

Leukemia following radiotherapy for uterine bleeding

Mortality due to leukemia among 4483 women treated with radiation to control uterine bleeding between 1925 and 1965 was twice as high as expected based on U.S. population rates (standardized mortality ratio (SMR) = 2.0; 95% confidence interval (CI): 1.4 to 2.8). Women were followed for an average of 26.4 years. Relative risk was highest 2 to 5 years after treatment (SMR = 8.1) and among women over 55 years at irradiation (SMR = 5.8). The usual method of treatment was intrauterine radium. Average radiation dose to active bone marrow was estimated on the basis of original radiotherapy records (median, 53 cGy). A linear dose-response model provided an adequate fit to the data. The average excess relative risk was 1.9% per cGy (95% CI: 0.8 to 3.2), and the average absolute risk was 2.6 excess leukemia deaths per million women per year per cGy (95% CI: 0.9 to 4.8). Chronic myeloid leukemia predominated during the first 15 years following exposure, whereas acute leukemias and chronic lymphatic leukemia were most common thereafter. The radiation doses experienced during treatment of benign gynecologic disease appear to result in greater leukemia risk per cGy average marrow dose than the considerably higher doses used to treat malignant disease, perhaps because of a decreased likelihood of killing potentially leukemic cells.

Cancer mortality in a radiation-exposed cohort of Massachusetts tuberculosis patients

The mortality experience of 13,385 tuberculosis patients treated between 1925 and 1954 in Massachusetts was determined through August 1986. Among 6,285 patients examined by X-ray fluoroscopy an average of 77 times during lung collapse therapy and followed for up to 50 yr (average = 25 yr), no increase in the total number of cancer deaths occurred [standardized mortality ratio (SMR) = 1.05, n = 424]. In contrast, the 7,100 patients treated by other means were at significant risk of dying from cancer (SMR = 1.3), especially of sites linked to cigarette smoking and alcohol use. Among the irradiated patients, estimates of mean radiation doses to the breast, lung, esophagus, and active bone marrow were 0.75, 0.84, 0.80, and 0.09 Gy, respectively. Cancers of the breast (SMR = 1.4, n = 62) and esophagus (SMR = 2.1, n = 14) were significantly increased. The risk of esophageal cancer, however, decreased with time since exposure. Lung cancer (SMR = 0.8, n = 69) and leukemia (SMR = 1.2, n = 17) were not elevated. Despite a wide range of doses to the lung, reaching over 8 Gy, there was no evidence of a dose response. Lung cancer risk also did not vary by time since exposure or age at exposure. Adjustment for smoking and the amount of lung tissue at risk did not appreciably modify these findings. These data suggest that frequent exposures to low doses of radiation over a period of several years increase the occurrence of cancer of the breast. When compared with studies of atomic bomb survivors, however, the fractionated exposures experienced by this cohort appear less effective in causing lung cancer than single exposures of the same total dose.

A case-control study of large bowel cancer and hormone exposure in women

Several lines of evidence indicate a potential role for hormonal or reproductive factors in the subsequent development of large bowel cancer in women. To evaluate the relationship between hormone exposure and large bowel cancer a case-control study was carried out in 18 Illinois hospitals. Female cases, ages 45-74 (n = 90), and controls (n = 208) were identified from an ongoing large bowel cancer study. Data were obtained from medical records, personal interviews, and a subsequent mail survey with a questionnaire specific to hormone usage. Menopausal estrogen use was found to be protective with respect to the subsequent development of large bowel cancer with an odds ratio of 0.6 (95% CI, 0.33-0.99). This effect remained after controlling individually for age at diagnosis, ever pregnant (yes/no), parity, age at first birth, hysterectomy with documented oophorectomy, cholecystectomy, and appendectomy. Simultaneous adjustment, using logistic regression, for age at diagnosis, parity, hysterectomy, and cholecystectomy resulted in an adjusted odds ratio for menopausal estrogen use and large bowel cancer of 0.5 (95% CI, 0.27-0.90). Subsite analysis revealed the protective effect to be strongest for the rectal cancer cases. These data support the hypothesis that exogenous hormones may alter the risk of large bowel cancer in women.

The influence of parity and exogenous female hormones on the risk of colorectal cancer

Evidence that female sex hormones may play a role in the subsequent development of colorectal cancer has accumulated from time trends in colorectal cancer rates and from epidemiologic studies. Using data available from the Cross Cancer Institute Northern Alberta Cancer Program, the relationship of parity, exogenous hormones and colorectal cancer was evaluated. Five hundred and twenty-eight colon cancer and 192 rectal cancer cases were identified and 349 nonendocrine cancers were selected as controls. All subjects were diagnosed and interviewed between 1969 and 1973. Protective associations between previous pregnancies and colorectal cancer were found in women over age 50 at diagnosis (OR = 0.5, 95% CI = 0.3-0.9) and in women who never used exogenous hormones (OR = 0.3, 95% CI = 0.2-0.7). Results from this study provide additional support for earlier suggestions that parity may have a protective effect against the development of colorectal cancer, similar to the effects reported in the case of breast, endometrial and ovarian tumors.

Substance data bases and right to know laws: application to occupational epidemiology

The Illinois Right to Know (RTK) law included requirements for substance lists to be submitted by companies to the Illinois Department of Labor (IDOL). This provided an opportunity to test the feasibility of identifying workplaces utilizing common chemicals for future epidemiologic investigations. A sample of IDOL files (n = 115) was obtained, and relevant data elements were coded. A second sample of substance names within these files (n = 1,015) was selected, and searches in three standard references were conducted to identify chemical descriptions. Equal proportions of employers and manufacturer/suppliers were in general compliance with RTK law reporting requirements (58%). Forty-five percent of substances sampled from employers (chemical users) and 71% of substances sampled from manufacturer/suppliers (chemical producers and distributors) could be identified. The ability to identify substances reported using chemical names was approximately equal across companies (90%), while the ability to identify substances with nonchemical names was greater in manufacturer (59%) than in employer (32%) files. This study suggests that the ability to identify potential occupationally exposed groups using this resource may be greater among manufacturers than among employers. Recognition of substances used in the workplace could be improved if companies were required to report chemical names.

Cancer mortality after multiple fluoroscopic examinations of the chest

Total cancer deaths were not increased among 2,074 women and 1,277 men who were fluoroscopically examined an average of 73 and 91 times, respectively, during lung-collapse therapy for tuberculosis (TB). Patients who did not receive this form of therapy (2,141 women and 1,418 men) and general population rates were used for comparison. All subjects were discharged alive from eight TB sanatoria in Massachusetts between 1930 and 1954; the average follow-up was 23 years. Deaths due to breast cancer were not increased among exposed females [standardized mortality ratio (SMR) = 1.0, n = 24], and SMRs greater than 2.1 could be excluded with 95% confidence. In contrast to other series, our inability to detect a breast cancer excess was likely due to lower breast doses (66 rad) and higher average ages at exposure (28 yr) and thus lower sensitivity. A deficit of lung cancer among exposed males and females was observed (SMR = 0.8, n = 26), even though increased risks have been observed among other populations exposed to similar dose levels. The estimated average lung dose was 91 rad, and SMRs greater than 1.2 for lung cancer could be excluded with 95% confidence. Overall, this study indicates that the radiation hazard of multiple low-dose exposures experienced over many years is not greater than currently accepted estimates for breast and lung cancer. For lung cancer the radiogenic risk may be less than predicted from high-dose, single-exposure studies.

A case-control study of diet and colo-rectal cancer

A case-control study of cancer of the colon and rectum has been conducted in Calgary, Alberta and Toronto, Ontario, Canada. A total of 348 cases of cancer of the colon and 194 cases of cancer of the rectum were individually matched by age, sex and neighbourhood of residence to 542 population controls and frequency match to 535 hospital controls who had undergone an abdominal operation. Each subject received a personal medical history questionnaire and a quantitative diet history questionnaire. Data on a number of potential non-nutrient risk factors for bowel cancer and on the consumption of 9 nutrients in the 2-month period up to 6 months before interview were analysed. The dietary data thus refer to recent diet consumed in a period antedating the diagnosis of, and in most cases symptoms from, large-bowel cancer in the cases, and a corresponding time period in the controls. The major findings were an elevated risk for those with a history of bowel polyps, and for those with an elevated intake of calories, total fat, total protein, saturated fat, oleic acid and cholesterol. No association was seen with an elevated intake of crude fibre, Vitamin C and linoleic acid. The nutrients for which an increased risk was demonstrated were highly correlated, though multivariate analysis using logistic regression indicated highest risk for saturated fat, with evidence of a dose-response relationship. The findings in both cancer sites, both sexes and with both sets of controls were quantitatively very similar. The population-attributable risk for colon and rectal cancer combined was estimated from the neighbourhood controls to be 41% for males and 44% for females for saturated fat intake and 9.8% and 6.4% respectively for any history of polyps.