Cancer in Jewish migrants to Israel

Adolescent animal product intake in relation to later prostate cancer risk and mortality in the NIH-AARP Diet and Health Study

BACKGROUND

Adolescent intake of animal products has been proposed to contribute to prostate cancer (PCa) development because of its potentially carcinogenic constituents and influence on hormone levels during adolescence.

METHODS

We used data from 159,482 participants in the NIH-AARP Diet and Health Study to investigate associations for recalled adolescent intake of red meat (unprocessed beef and processed red meat), poultry, egg, canned tuna, animal fat and animal protein at ages 12-13 years with subsequent PCa risk and mortality over 14 years of follow-up. Cox proportional hazard regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of total (n = 17,349), advanced (n = 2,297) and fatal (n = 804) PCa.

RESULTS

Suggestive inverse trends were observed for adolescent unprocessed beef intake with risks of total, advanced and fatal PCa (multivariable-adjusted P-trends = 0.01, 0.02 and 0.04, respectively). No consistent patterns of association were observed for other animal products by PCa outcome.

CONCLUSION

We found evidence to suggest that adolescent unprocessed beef intake, or possibly a correlate of beef intake, such as early-life socioeconomic status, may be associated with reduced risk and mortality from PCa. Additional studies with further early-life exposure information are warranted to better understand this association.

Cancer Incidence in Turin: The Effect of Migration

Aims and Background

Studies on migrant populations have been of great value in clarifying the role of environmental factors in cancer occurrence. Most of them consider migrants from other countries or continents. Turin, the target territory of this study, was an important area of Internal migration initially from the East, and more recently from southern Italy.

Methods

The study compared incidence rates (age-standardized) of the native population, of the migrants and incidence rates of the Cancer Registries located in the four main areas of origin.

Results

Overall incidence rates in migrants from southern Italy were intermediate compared with those of the stable populations of the South and the North. The same effect was not true for people from the North-East, who migrated in earlier decades. In this population, migration towards lower-incidence areas did not reduce cancer incidence. Migrants from the South showed a significant increase in intestinal, breast, and tobacco-related tumors compared to the stable southern population. No effect of migration was found for cancer of the mouth, pharynx, esophagus, stomach or corpus uteri. Incidence of liver cancer in migrant southern males was significantly different from the stable and the native north-western population.

Conclusions

The results, based on incidence data, validated previous findings based on mortality data on the effect of Italian Internal migrations and showed that migrants underwent changes in some environmental exposures. In particular, migrants from the South to the North of Italy came into contact with new risk factors, with an increase in occurrence of cancer.

European Code against Cancer 4th Edition: Ultraviolet radiation and cancer

Ultraviolet radiation (UVR) is part of the electromagnetic spectrum emitted naturally from the sun or from artificial sources such as tanning devices. Acute skin reactions induced by UVR exposure are erythema (skin reddening), or sunburn, and the acquisition of a suntan triggered by UVR-induced DNA damage. UVR exposure is the main cause of skin cancer, including cutaneous malignant melanoma, basal-cell carcinoma, and squamous-cell carcinoma. Skin cancer is the most common cancer in fair-skinned populations, and its incidence has increased steeply over recent decades. According to estimates for 2012, about 100,000 new cases of cutaneous melanoma and about 22,000 deaths from it occurred in Europe. The main mechanisms by which UVR causes cancer are well understood. Exposure during childhood appears to be particularly harmful. Exposure to UVR is a risk factor modifiable by individuals' behaviour. Excessive exposure from natural sources can be avoided by seeking shade when the sun is strongest, by wearing appropriate clothing, and by appropriately applying sunscreens if direct sunlight is unavoidable. Exposure from artificial sources can be completely avoided by not using sunbeds. Beneficial effects of sun or UVR exposure, such as for vitamin D production, can be fully achieved while still avoiding too much sun exposure and the use of sunbeds. Taking all the scientific evidence together, the recommendation of the 4th edition of the European Code Against Cancer for ultraviolet radiation is: "Avoid too much sun, especially for children. Use sun protection. Do not use sunbeds."

Prostate cancer: is it time to expand the research focus to early-life exposures?

Although the contribution of lifestyle and environment (non-genetic factors) to prostate carcinogenesis is indicated by international variation in prostate cancer occurrence and migration studies, no conclusive modifiable risk factors have yet been identified. One possible reason for this may be the dearth of epidemiological research on exposures experienced early in life, when the immature prostate may be more susceptible to carcinogenic exposures. In this Opinion article, we summarize the rationale for studying early-life exposures, describe the small body of early-life research and its associated challenges, and point to solutions for future research.

Country of origin, age at migration and risk of cutaneous melanoma: a migrant cohort study of 1,100,000 Israeli men

Cutaneous melanoma (CM) is a common cancer with increasing incidence in many parts of the world where light-skinned populations live. We conducted a large-scale nationally representative migrant cohort study to assess country of origin and age at migration as predictors of CM, controlling for possible confounders. Data on 1,086,569 Israeli Jewish males, who underwent a general health examination before compulsory military service at ages 16-19 between the years 1967-2005, were linked to Israel National Cancer Registry to obtain incident CM up to 2006. Cox proportional hazards was used to model time to event. Overall, 1562 incident cases were detected during 19.3 million person-years of follow-up. Origin was a strong independent predictor of CM. Incidence was higher for European (hazard ratio [HR] = 4.08, 95% confidence interval [CI]: 3.55-4.67) and Israeli origin (HR = 2.92, 95% CI: 2.25-3.79) compared to N. African/Asian origin, adjusted for year of birth, years of education, residential socio-economic position, rural residence and body surface area (or height). Among those of European origin, the adjusted risk was significantly lower for those who immigrated after the age of 10 years (HR = 0.58, 95% CI: 0.45-0.73) but not for younger ages (HR = 1.02, 95% CI 0.84-1.23) compared to Israeli born. The high rates of CM among men of European origin and the almost twofold lower risk among those immigrating after age 10 provide solid support for the deleterious role of childhood sun exposure as a risk factor for melanoma. These findings will serve in directing public health and research efforts.

Incidence of celiac disease among second-generation immigrants and adoptees from abroad in Sweden: evidence for ethnic differences in susceptibility

BACKGROUND AND AIMS

The incidence of celiac disease (CD) shows large, worldwide variation. However, whether its causes are environmental (gluten-containing diet) or genetic (specific haplotype) have not been established. The aim of the present study is to examine the incidence of CD among second-generation immigrants and adoptees from abroad to disentangle genetic/ethnic versus environmental influences (assuming that immigrants have similar gluten exposures to native Swedes, and thus differ from them only in terms of their genetic background).

METHODS

Second-generation immigrants and adoptees from abroad were identified in the MigMed 2 Database and were followed until diagnosis of CD, death, or the end of study. Standardized incidence ratios (SIRs) were calculated among these immigrants with native Swedes as the reference group.

RESULTS

A total of 1,050,569 children were defined as second-generation immigrants and the overall SIR of CD (SIR = 0.89, 95% confidence interval 0.84-0.94) was significantly lower than that of native Swedes. The incidence of CD among children with parents from Western, Eastern, and Northern European countries was similar to that in native Swedes, but was lower for those with parents from low-prevalence countries, especially Eastern and Southeast Asian countries. A total of 51,557 children born in foreign countries were adopted by Swedes. Adoptees from Eastern Asia had a significantly decreased SIR of CD.

CONCLUSIONS

The decreased incidence of CD in second-generation immigrants and some groups of adoptees from abroad strongly suggests that ethnic genetic heterogeneity may contribute to the worldwide variation in CD incidence.

Ethnic differences in incidence of type 1 diabetes among second-generation immigrants and adoptees from abroad

OBJECTIVE

The incidence of type 1 diabetes shows a large variation worldwide, but whether the causes are environmental or genetic has not been settled. We examine here the incidence of type 1 diabetes among second-generation immigrants and adoptees from abroad to disentangle genetic/ethnic vs. environmental influence, assuming adoptees from abroad have similar environmental exposures compared with the native Swedes, with the only difference in their genetic background.

METHODS

Second-generation immigrants and adoptees from abroad were retrieved from the MIGMED2 database, and they were followed up until the diagnosis of type 1 diabetes, death, or the end of study. Standardized incidence ratios (SIRs) were calculated for type 1 diabetes among these immigrants compared with native Swedes.

RESULTS

A total of 1,050,569 children were defined as second-generation immigrants and the overall SIR of type 1 diabetes was significantly decreased. A decreased risk was observed for all countries of origin, with an exception for children with parents from Finland. A total of 51,557 children born in foreign countries were adopted by Swedes. Adoptees from Eastern Europe, Soviet countries, India, Pakistan, Afghanistan, East and Southeast Asia, Chile, and other Central and South American countries had a significantly decreased SIR.

CONCLUSIONS

The decreased incidence of type 1 diabetes observed in some second-generation immigrants and adoptees from abroad strongly suggests that ethnic genetic heterogeneity could play an important role on type 1 diabetes.

Combined effect of NAT2, MTR and MTHFR genotypes and tobacco on bladder cancer susceptibility in Tunisian population

BACKGROUND

Cigarette smoking is the predominant risk factor for bladder cancer. This risk may be modified by polymorphisms in carcinogens metabolism genes; including those involving the N-acetyl transferase 2 (NAT2) which have been correlated with decreased enzyme activities. Moreover, folate insufficiency can induces carcinogenesis by decreasing DNA methylation. Methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MTR) are enzymes that play central roles in the folate metabolic pathway. The MTHFR 677*T and MTR 2756*G variants are associated with decreased enzyme activity.

METHODS

In this work, we have conducted a case-control study in order to assess the combined effect of tobacco, slow NAT2 variants, MTHFR 677*T and MTR 2756*G alleles on bladder cancer development in North Tunisia.

RESULTS

For MTR A2756G, alleles and genotypic distributions differed significantly between cases and controls (p = 0.00009, OR = 3.27, CI 95% 1.76-6.12). While, in non-smokers patients the slow NAT2 did not appear to influence bladder cancer susceptibility; our results suggested that it might act with an additive contribution with tobacco as well as with that determined by MTR 2756 AG or 2756 GG genotypes (p = 0.0008). Identical cumulative effect was detected for slow NAT2 and MTHFR 677*T variant (p = 0.0003; OR = 36.6; CI 95% 3.4-935.3).

CONCLUSION

The strongest result obtained by this study was for an additive effect between smoking status, slow NAT2 variants, MTR 2756*G and MTHFR 677*T alleles, in affecting bladder cancer risk.

Mortality in first generation white immigrants in California, 1989-1999

OBJECTIVE

To identify mortality differentials in the first generation non-Hispanic White (NHW) immigrants in California for 1989 through 1999.

METHODS

First generation NHW immigrants (107,432) were identified in California Death Certificate files by place of birth outside the US and were grouped into Anglo-Saxon dominant, Northern, Western, Eastern, and Southern Europe, former USSR, Arabs and non-Arab Middle Eastern areas. US-born NHW (1,480,347) were used as standard to determine proportional mortality ratios (PMR) for major causes of death including: cancers, coronary heart disease, cerebrovascular accidents, chronic obstructive pulmonary disease (COPD), HIV/AIDS, accidents, diabetes, pneumonia, suicide, and homicide.

RESULTS

All immigrants had significantly higher PMR for suicide and with few exceptions for cardiovascular diseases. Lower PMR was recorded for COPD and homicide. No difference was noticed for pneumonia and accidents. Cancer deaths were generally higher in European immigrants.

CONCLUSIONS

Mortality patterns of NHW immigrants reflect the mixed impacts of acculturation, ethnic-specific characteristics, and psychological well being.

Ambient UV, personal sun exposure and risk of multiple primary melanomas

OBJECTIVE

Sun exposure is the main cause of melanoma in populations of European origin. No previous study has examined the effect of sun exposure on risk of multiple primary melanomas compared with people who have one melanoma.

METHODS

We identified and enrolled 2,023 people with a first primary melanoma (controls) and 1,125 with multiple primary melanomas (cases) in seven centers in four countries, recorded their residential history to assign ambient UV and interviewed them about their sun exposure.

RESULTS

Risk of multiple primary melanomas increased significantly (P<0.05) to OR=2.10 for the highest exposure quarter of ambient UV irradiance at birth and 10 years of age, to OR=1.38 for lifetime recreational sun exposure, to OR=1.85 for beach and waterside activities, to OR=1.57 for vacations in a sunnier climate, to OR=1.50 for sunburns. Occupational sun exposure did not increase risk (OR=1.03 for highest exposure). Recreational exposure at any age increased risk and appeared to add to risk from ambient UV in early life.

CONCLUSIONS

People who have had a melanoma can expect to reduce their risk of a further melanoma by reducing recreational sun exposure whatever their age. The same is probably true for a person who has never had a melanoma.

Breast Cancer among Immigrants: A Systematic Review and New Research Directions

This paper highlights the relationship between migration and female breast cancer. A comprehensive review aimed at identifying risk and protective factors that cut across races and ethnicities was performed. A total of 79 studies (1971-2005) from 16 countries were reviewed. The findings are consistent with existing knowledge about the importance of potentially modifiable environmental and behavioral determinants of risk, acting both pre- and post-migration. While the acculturation-based risk transition model is strong, it is not always supported. As a new direction for migrant studies, we extrapolate the review findings to the experience of Eastern European (EE) immigrants. Health data on this population, typically characterized by low health motivation and passive receipt of preventive efforts, are largely unavailable. Based on relevant theory, empirical and qualitative studies, two breast cancer prevention models for the EE immigrant population are proposed and the need for future research using ethnically disaggregated data is discussed.

Multiple common naevi in Israeli adolescents

The most prominent known phenotypic risk factor for the development of melanoma is a large number of common melanocytic naevi. The aims of this study were to determine the prevalence of multiple common naevi in a group of 17-year-olds and to identify possible associated risk factors. The study subjects were approximately 40,000 female and 60,000 male 17-year-old Jewish Israelis presenting to army recruitment centres for compulsory military service during a 1-year period from January 2003 to December 2003. Data were gathered on whole-body naevi count, years of education, place of residence and place of birth of the recruit, his/her parents and paternal grandparents. The count of whole-body naevi was carried out by military physicians. The multiple naevi phenotype was defined by the presence of more than 50 naevi. The prevalence of the phenotype was highest amongst recruits of American origin and lowest amongst those of Asian and African origin (P < 0.0001). The prevalence differed in different population centres, the highest being in the coastal cities of Haifa and Tel Aviv. This pattern corresponded to the geographical distribution of melanoma in Israel. Amongst male conscripts, the phenotype was more common in the better educated group (> or =12 years) than in the poorer educated conscripts (< or = 11 years) (P = 0.051). When adjusted for the factors studied, a significant correlation was found between a high multiple common naevi count and American and European origin and residence in coastal cities, reflecting the complex interplay between endogenous and exogenous factors of melanoma.

Migration history, acculturation, and breast cancer risk in Hispanic women

BACKGROUND

Migrant studies have shown that breast cancer risk increases in women who move from countries with low incidence rates to countries with high rates. We examined the influence of migration history and acculturation on breast cancer risk in Hispanic women ages 35 to 79 years.

METHODS

In a population-based case-control study conducted in the San Francisco Bay Area, information on migration history, language usage, and other risk factors for breast cancer was collected through an in-person interview for 991 cases and 1,285 controls.

RESULTS

Breast cancer risk was 50% lower in foreign-born Hispanics than U.S.-born Hispanics. Risk increased with increasing duration of residence in the United States, decreasing age at migration, and increasing acculturation. Among long-term foreign-born residents, risk was lower among Hispanics who moved to the United States at age > or =20 years and those who spoke mostly Spanish. The difference in risk between third-generation or higher-generation Hispanics and recent migrants from rural areas was approximately 6-fold in postmenopausal women and 4-fold in premenopausal women. Adjustment for differences in the distribution of breast cancer risk factors greatly attenuated the associations with migration patterns in premenopausal women; reduced risks remained only in those who resided in the United States for <10 years or migrated at age > or =30 years. In postmenopausal women, a 25% to 30% lower risk remained among long-term residents and those who migrated to the United States before age 20 years.

CONCLUSIONS

These findings suggest the importance of yet unidentified protective factors among both recent premenopausal migrants and postmenopausal migrants.

Investigation of genetic polymorphisms and smoking in a bladder cancer case-control study in Argentina

We investigated the role of glutathione S-transferase (GST) enzymes (M1, T1), methylenetetrahydrofolate (MTHFR) 677 and 1298, and the NAD(P)H:quinone oxidoreductase (NQO1) polymorphisms in a population-based bladder cancer case-control study in Argentina. Buccal cell DNA was obtained from 106 cases and 109 controls. The strongest evidence was for an interaction between NQO1 genotype and smoking. For ever smoking vs. never smoking the odds ratio was 8.6 (95% confidence interval (CI) 2.7-27), in the CC genotype, and 1.3 (95% CI 0.5-3.5) in the CT and TT genotypes combined. Also, elevated bladder cancer risks associated with GSTM1 and GSTT1 null genotypes were found in smokers. Having both null polymorphisms conferred the highest risks. The MTHFR 677 CT and TT polymorphisms appeared protective against bladder cancer.

Active smoking, household passive smoking, and breast cancer: evidence from the California Teachers Study

BACKGROUND

There is great interest in whether exposure to tobacco smoke, a substance containing human carcinogens, may contribute to a woman's risk of developing breast cancer. To date, literature addressing this question has been mixed, and the question has seldom been examined in large prospective study designs.

METHODS

In a 1995 baseline survey, 116 544 members of the California Teachers Study (CTS) cohort, with no previous breast cancer diagnosis and living in the state at initial contact, reported their smoking status. From entry into the cohort through 2000, 2005 study participants were newly diagnosed with invasive breast cancer. We estimated hazard ratios (HRs) for breast cancer associated with several active smoking and household passive smoking variables using Cox proportional hazards models.

RESULTS

Irrespective of whether we included passive smokers in the reference category, the incidence of breast cancer among current smokers was higher than that among never smokers (HR = 1.32, 95% confidence interval [CI] = 1.10 to 1.57 relative to all never smokers; HR = 1.25, 95% CI = 1.02 to 1.53 relative to only those never smokers who were unexposed to household passive smoking). Among active smokers, breast cancer risks were statistically significantly increased, compared with all never smokers, among women who started smoking at a younger age, who began smoking at least 5 years before their first full-term pregnancy, or who had longer duration or greater intensity of smoking. Current smoking was associated with increased breast cancer risk relative to all nonsmokers in women without a family history of breast cancer but not among women with such a family history. Breast cancer risks among never smokers reporting household passive smoking exposure were not greater than those among never smokers reporting no such exposure.

CONCLUSION

Our study provides evidence that active smoking may play a role in breast cancer etiology and suggests that further research into the connection is warranted, especially with respect to genetic susceptibilities.

Intakes of fish and marine fatty acids and the risks of cancers of the breast and prostate and of other hormone-related cancers: a review of the epidemiologic evidence

Marine fatty acids, particularly the long-chain eicosapentaenoic and docosahexaenoic acids, have been consistently shown to inhibit the proliferation of breast and prostate cancer cell lines in vitro and to reduce the risk and progression of these tumors in animal experiments. However, whether a high consumption of marine fatty acids can reduce the risk of these cancers or other hormone-dependent cancers in human populations is unclear. Focusing primarily on the results of cohort and case-control studies, we reviewed the current epidemiologic literature on the intake of fish and marine fatty acids in relation to the major hormone-dependent cancers. Despite the many epidemiologic studies that have been published, the evidence from those studies remains unclear. Most of the studies did not show an association between fish consumption or marine fatty acid intake and the risk of hormone-related cancers. Future epidemiologic studies will probably benefit from the assessment of specific fatty acids in the diet, including eicosapentaenoic and docosahexaenoic acids, and of the ratio of these to n-6 fatty acids, dietary constituents that have not been examined individually very often.

Cancer risks in Nordic immigrants and their offspring in Sweden

Numerous migrant studies on cancer have been carried out, but little data are available on cancer incidence upon inter-European migration. We used the nationwide Swedish Family-Cancer Database to analyse cancer risk among Nordic immigrants and their offspring in Sweden. The parental population had entered Sweden in their 20s and they had become parents in Sweden. Finns were the largest immigrant group including approximately 183,000 parents and 278,000 offspring. We calculated the standardised incidence ratios (SIRs) and 90 or 95% confidence intervals (CIs) for 26 cancer sites using native Swedes as a reference. Cancers in the first generation immigrants followed the rates in the countries of origin, reaching high SIRs for tobacco-related, cervical and testicular cancer among Danes and for stomach cancer among Finns. Only a few cancers, such as cervical cancer was increased in the second generation. At many sites, particularly among the Finns, protection was observed in the first generation. At three sites, breast, ovary and urinary bladder, where plausible evidence for protection was found even among offspring, this was not reinforced among the offspring of compatriot parents, which is inconsistent with heritable effects. Protection against melanoma was strongest among the offspring of compatriots, but the contribution of cultural factors cannot be excluded. As the parents immigrated to Sweden in their 20s, their cancer pattern, including habits and life style, appeared to be set before that age because the differences to Swedes persisted even in cancers that predominate in old age. Immigrant populations would appear to be attractive subjects to study etiological factors of cancer at sites where causes remain poorly understood, such as testicular cancer.

Cancer risks in first-generation immigrants to Sweden

We used the nationwide Swedish Family-Cancer Database to analyse cancer risks in 613,000 adult immigrants to Sweden. All the immigrants had become parents in Sweden and their median age at immigration was 24 years for men and 22 years for women. We calculated standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for 18 cancer sites using native Swedes as a reference. Data were also available from compatriot marriages. All cancer was decreased by 5% and 8% for immigrant men and women, respectively. However, most of the male increase was due to lung cancer for which male immigrants showed a 41% excess. Among individual cancer sites and immigrant countries, 110 comparisons were significant, 62 showing protection and 48 an increased risk. Most of the differences between the rates in immigrants and Swedes could be ascribed to the variation of cancer incidence in the indigenous populations. Some high immigrant SIRs were 5.05 (n = 6, 95% CI 1.82-11.06) for stomach cancer in Rumanian women and 2.41 (41, 1.73-3.27) for lung cancer in Dutch men. At some sites, such as testis, prostate, skin (melanoma), kidney, cervix and nervous system, the SIRs for immigrants were decreased; in some groups of immigrants SIRs were about 0.20. The highest rates for testicular cancer were noted for Danes and Chileans. Women from Yugoslavia and Turkey had an excess of thyroid tumours. All immigrant groups showed breast, endometrial and ovarian cancers at or below the Swedish level but the differences were no more than 2-fold.

Cancer risks in second-generation immigrants to Sweden

We used the nationwide Swedish Family-Cancer Database to analyze cancer risks in Sweden-born descendants of immigrants from European and North American countries. Our study included close to 600,000 0-66-year-old descendants of an immigrant father or mother. We calculated standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for 17 cancer sites using native Swedes as a reference. All cancer was marginally below the Swedish incidence in offspring of immigrant origin. Decreased SIRs were observed for breast cancer among Norwegian descendants, melanoma among descendants of Hungarian fathers and ovarian and bladder cancer among descendents of Finnish mothers, all consistent with the difference in cancer incidence between Swedes and the indigenous populations. Cervical cancer was increased in daughters of Danish men, whereas thyroid cancer and non-Hodgkin's lymphoma were in excess in offspring of parents of Yugoslav and Asian descent. Even these results agreed with the high incidence rates in parents compared to Swedes, except that for non-Hodgkin's lymphoma other explanations are needed; these may be related to immune malfunction. Comparison of the results between the first- and the second-generation immigrants suggest that the first 2 decades of life are important in setting the pattern for cancer development in subsequent life. Birth in Sweden sets the Swedish pattern for cancer incidence, irrespective of the nationality of descent, while entering Sweden in the 20s is already too late to influence the environmentally imprinted program for the cancer destiny.

Cancer risks in childhood and adolescence among the offspring of immigrants to Sweden

We used the nation-wide Swedish Family-Cancer Database to analyse the risk of nervous system tumours, leukaemia and non-Hodgkin's lymphoma in age groups 0-4 and 0-19 years among Swedish-born offspring of immigrants. The study included 850 000 individuals with an immigrant background, including European, Asian and American parents. We calculated standardised incidence ratios for the above three malignancies using Swedish offspring as a reference. Subjects were grouped by region or by selected countries of parental origin. No group differed significantly from Swedes in the occurrence of nervous system neoplasm or leukaemia. Offspring of Yugoslav fathers (SIR 2.27) and Turkish parents were at increased risk of non-Hodgkin's lymphoma. The highest risk was noted for non-Hodgkin's lymphoma among young offspring (0-4 years) of two Turkish parents (6.87). The currently available limited data on rates for childhood non-Hodgkin's lymphoma in these countries do not explain the risk in the offspring of immigrants. Yugoslavs and Turks are recent immigrant groups to Sweden, and their offspring have been subject to much population mixing, perhaps leading to recurring infections and immunological stimulation, which may contribute to their excess of lymphomas.

Cancer mortality in migrants from the British Isles and continental Europe to New South Wales, Australia, 1975-1995

Routinely collected data for New South Wales were used to analyse cancer mortality in migrants from the British Isles, southern Europe and eastern Europe according to duration of residence in Australia. A case-control approach compared deaths from cancer at one site with deaths from all other cancers, adjusting for age, sex and calendar period. Compared with the Australia-born, migrants had a significantly lower risk of dying from cancers of the mouth/pharynx and prostate (migrants from each region), colon/rectum (from the British Isles and southern Europe) and lung (female southern European migrants), evident from the time of migration and maintained for 30 years after migration. Whereas a deficit of deaths from colorectal cancer remained in migrants from southern Europe, a clear gradient of increasing risk with duration of stay in Australia was apparent. A similar trend was seen with respect to kidney cancer in southern European migrants. Persistent excess risks of death from stomach cancer were seen in all migrant groups, from lung cancer in British migrants and from liver cancer in southern and eastern European migrants. Although the risk of death from breast cancer increased significantly with duration in Australia in southern European migrants, the increase was not monotonic, as the relative risk in the first 10 years after migration was almost the same as that after more than 30 years. The pattern of risk for cancers of the prostate and mouth/pharynx suggests some protective role for inheritance or maintained cultural factors.

Cancer mortality in East and Southeast Asian migrants to New South Wales, Australia, 1975-1995

Routinely collected data for New South Wales were used to analyse cancer mortality in migrants born in East or Southeast Asia according to duration of residence in Australia. A case-control approach compared deaths from cancer at particular sites with deaths from all other cancers, adjusting for age, sex and calendar period. Compared with the Australian-born, these Asian migrants had a 30-fold higher risk of dying from nasopharyngeal cancer in the first 2 decades of residence, falling to ninefold after 30 years, and for deaths from liver cancer, a 12-fold risk in the first 2 decades, falling to threefold after 30 years. The initial lower risk from colorectal, breast or prostate cancers later converged towards the Australian-born level, the change being apparent in the third decade after migration. The relative risk of dying from lung cancer among these Asian migrants was above unity for each category of duration of stay for women, but at or below unity for men, with no trend in risk over time. An environmental or lifestyle influence for nasopharyngeal and liver cancers is suggested as well as for cancers of colon/rectum, breast and prostate.

Cancer epidemiology in migrant populations

Migrant studies have taken advantage of the wide geographical variation in cancer risk. Cancer rates in migrants, obtained from routinely collected incidence or mortality statistics, are compared with those in the host country and in the country of origin; the rate of change with time since migration (or age at migration) and in subsequent generations is assessed; and the results are interpreted in the light of differences in socio-economic status and the degree of cultural assimilation. Rapid changes in cancer risk following migration imply that life-style or environmental factors are of overriding importance in aetiology. The susceptibility of fair-skinned races to ultraviolet (UV)-associated skin cancers is an example of racial differences based on inherited factors, but the long-term excess or deficit of other cancers in migrants has not yet been attributed definitively to genetic rather than persisting life-style factors. Are there racial differences in metabolism, DNA repair mechanisms or altered expression of oncogenes or tumour suppressor genes? Several genetic polymorphisms affecting the metabolism of known occupational carcinogens or hormonal factors do vary by race. While classical epidemiology has shown that the environment predominates in determining cancer incidence, molecular epidemiology has identified several examples of genetically determined differences between races.

Studies of cancer in migrants: rationale and methodology

Migrant populations comprise substantial numbers of individuals who have undergone a change in their environment, sociocultural and physical. The corresponding changes in risk for different cancers have, therefore, been widely used to infer the relative importance of environmental factors versus inherited predisposition in cancer aetiology. The uncontrolled experiment of migration also provides an indication of the possible effects of certain preventive interventions at the population level--especially with respect to diet. In the past, there has been a surprising lack of attention to analytical methods for migrant data, and we review the epidemiological methods available to best bring out the relevant differences in risk. The major sources of bias which confuse interpretation are also described. Migrant studies are classified into four groups, in a hierarchy corresponding to the amount of information which they can provide, and examples of each type are provided.

Cervical cancer: incidence and survival in migrants within Spain

STUDY OBJECTIVE

This study examined the incidence of cervical cancer and survival rates according to migrant experience of women from different regions of Spain to Girona, Catalonia (Spain).

DESIGN

Using data from the population based cancer registry of Girona for the period 1980-89, crude and age adjusted incidence rates were calculated for local-born and first generation migrants from other Spanish regions. The age standardised rate ratio (SRR) was calculated and Cox's regression model was used to adjust survival according to migrant status for age and stage at diagnosis.

MAIN RESULTS

The incidence of cervical cancer was significantly higher in first generation Spanish migrants compared with locally born women (SRR: 2.02; 95% CI 1.40:2.92). The stage at diagnosis was more advanced among migrants. Survival probability was significantly associated with stage at diagnosis, but age and region of birth were not.

CONCLUSIONS

Migrants from the southern Spanish regions show a twofold excess in the incidence of cervical cancer compared with the Girona-born female population. Cases of cervical cancer in migrants are diagnosed at a more advanced stage and as a consequence have a poorer prognosis.

Variability of neoplastic parameters in colon tumours, and its significance in diagnostic practice

We have reviewed the value of individual variability in the reaction of tissues to treatment with carcinogens, and the manifestation of this variability in different morphological (histological, morphometric, and ultrastructural), histochemical and immunohistochemical parameters generated in tumorous tissues. Moreover, we also reviewed data in the literature on individual variability in the manifestation of some biochemical and immunochemical markers which are accumulated in the serum of tumour-bearing patients and which are characteristic for the different phases of tumourigenesis. The high variability of different tumorous parameters suggests that none can be utilized alone as a conclusive marker of neoplasia and that only their combined use can give objective information. We also reviewed the impact of this variability in the evaluation of various pathological methods to detect different stages of neoplastic transformation in the colon. It has been concluded that none of the present approaches can be absolutely conclusive and without false results, and that objective information regarding early cancerous changes may be obtained only by use of combined analyses utilizing several laboratory methods. The diagnostic procedures should be based on the complex utilization of all appropriate methods using the quantitative interpretation of the obtained data. Multivariate analysis of many parameters should be very effective for the prediction of therapeutic results.

Cancer incidence in Estonian migrants to Sweden

Cancer incidence in Estonians who took refuge in Sweden in 1944-1945 has been compared with that in the total Swedish population and that among Estonians in Estonia in 1974-1985 using data from the Swedish and the Estonian countrywide population-based cancer registries. The vast majority of the Estonian immigrants studied had been living in Sweden for 30 years when the follow-up with respect to cancer incidence started in this investigation. In spite of the long residence in Sweden, differences in cancer incidence could be observed between these immigrants and the total Swedish population. The age-standardized incidence of stomach cancer was higher in the Estonian migrants than in the total Swedish population (SIR = 1.6 and 2.1 for males and females, respectively). Breast cancer incidence was lower in the migrant women (SIR = 0.75) and lung cancer incidence higher in migrant men (SIR = 1.5). An increased incidence of colorectal cancer was also found for both sexes in the migrant population (SIR = 1.4 for both males and females). A comparison between Estonians in Estonia and the total Swedish population revealed that the cancer incidence for the Estonians was lower than expected at age 70 and over. Male lung cancer and stomach cancer showed a higher incidence in the Estonian population than in the Swedish and in the migrant populations. The migrant population showed an intermediate incidence relative to Estonians in Estonia and the entire Swedish population. The colon-cancer risk in Estonian migrants to Sweden was higher than the risk for Estonians in Estonia and for the Swedish population. This contrasts with most findings in the present and other studies on intermediate risks of migrants compared to the risks in the country of origin and in the new country of residence.

Increased risk of nasopharyngeal carcinoma among males of French origin born in Maghreb (north Africa)

A study on the incidence of nasopharyngeal carcinoma (NPC) has been performed in the Provence-Alpes-Côte d'Azur (PACA) region, South of France, where Maghrebian migrants represent 10% of the population. During the years 1986-1990, 76 cases of NPC were diagnosed, of which 44 were French by birth, 25 were Maghrebian migrants and 7 were other migrants. We found that 36% of the French patients were either born in endemic areas or had lived there for more than 15 years. Standardized annual incidence rates of NPC among Maghrebian migrants remained close to those observed in North Africa, while, standardized annual incidence rates for French by birth in the PACA region were similar to those observed in cancer registries in other regions of France and countries of low incidence. However, for males of French origin born in Maghrebian countries, the incidence of NPC (all cases being of undifferentiated type) was 5.7 times higher than that of males of French origin born in France (p = 0.00001). These results favor a critical role of environmental factors in the risk of NPC.

Cancer risks among European migrants in São Paulo, Brazil

Using both mortality and incidence data, cancer risk in Italian, Spanish and Portuguese migrants to São Paulo were compared with those in the Brazil-born population, and with those in their countries of origin. Italian and Spanish migrants show changes in cancer risks which are rather similar to those observed in migrants of the same origin in other parts of South America: they increase their rates of oropharyngeal, oesophageal, cervical and breast cancers and they decrease their rates of lung cancers. However, for cancer of the oesophagus, the changes are greater in São Paulo, where migrants acquire rates similar to those of the natives. For colon cancer, rates in Italian migrants decrease in the low risk area of São Paulo and increase in the high risk area of Argentina. Changes in Portuguese migrants are less evident: their rates of colorectal cancer remain high, and, as found for Japanese migrants in São Paulo, they also retain their higher risks of stomach cancer.

Breast cancer in Denmark. Incidence, risk factors, and characteristics of survival

In Denmark, incidence of female breast cancer remained constant from 1943 to around 1960, whereafter a steady increase has occurred, the level today being about 50% higher than in 1960. No equivalent rise has been observed for breast cancer mortality. Influence of hormonal and dietary factors on breast cancer risk and survival was evaluated in a combined population-based case-control and follow-up study, including 2,445 women, aged less than 70 years, diagnosed with breast cancer in Denmark between 1 March 1983 and 31 August 1984, identified from the files of the nation-wide clinical trial of the Danish Breast Cancer Co-operative Group (DBCG) and the Danish Cancer Registry. The control group was an age-stratified random sample of the general female population, selected from the Central Population Register. Data on risk factors were collected by self-administered questionnaires. Clinical and pathological tumour characteristics derived from DBCG. The case-control analysis confirmed an overall increased risk of breast cancer associated with urban residence, high social status, nulliparity, early age at menarche, late age at natural menopause, hormonal replacement therapy, high dietary fat intake, and high alcohol consumption in a subgroup. It failed to detect an association with age at first childbirth, oral contraceptives, smoking, intake of vegetables, tea, coffee, and sweeteners. Survival was determined by tumour size, skin invasion, number of positive lymph nodes, and grade. There was no relation between survival and reproductive or hormonal factors, dietary variables, alcohol consumption, or smoking. However, a complex relationship may exist between survival and body mass index.

Insulin-cancer relationships: possible dietary implication

Insulin is a major anabolic hormone in mammals and its involvement in malignancies is well documented. An attempt is made to classify experimental and human cancers into four groups, according to the way the tumors are affected by, or interact with, insulin. Such an approach provides a better understanding of the dietary effects on tumorigenesis. Since human cancers are of the insulin-producing/secreting or insulin-dependent types, it is suggested that screening of individuals for blood insulin level and reducing the insulin status by dietary means may lead to a decreased risk of cancer. Anti-insulin drugs may be useful as supplements to therapeutic treatment.