Cancer in the European population of Harare, Zimbabwe, 1990-1992

The data presented from the population-based cancer registry in Harare, Zimbabwe, represent the first information on the incidence of cancer in a population of European origin living in Southern Africa for over 30 years. Their cancer pattern is more or less typical of white populations of high socio-economic status living in Europe or North America, with elevated incidence rates of breast cancer, large-bowel cancer and, in women, lung cancer. However, there are also several unusual features, with extremely high incidence rates of skin cancers, including melanomas, and higher rates of liver and bladder cancer than normally seen in white populations.

Cancer in the African population of Harare, Zimbabwe, 1990-1992

The data presented from the population-based cancer registry in Harare, Zimbabwe, represent the first information on the incidence of cancer in Southern Africa for almost 20 years. In the African population in Zimbabwe there are several features in common with other countries in sub-Saharan Africa: high rates of liver, prostate and cervix cancer, low rates of large-bowel cancer and breast cancer. Also, as reported from southern and south-eastern Africa, there are relatively high incidence rates of cancers of the oesophagus, bladder and (in men) lung. The AIDS epidemic has given rise to a striking increase in incidence of Kaposi's sarcoma (now the commonest cancer of African men), but there is not much evidence for an increase in incidence of non-Hodgkin lymphomas nor, although rates are very high, of cervical cancer.

Occupational risk factors for lung cancer in Tianjin, China

Information about occupation and industry of cancer patients is routinely recorded in the Cancer Registry of Tianjin, People's Republic of China. Occupational risk factors of lung cancer for the period of 1981-1987 were assessed using other cancers as controls. For each occupation and industry, workers employed in it were considered exposed and were compared with all other workers. Elevated risks were found for a number of industries for both sexes, including, in particular, the textile, wood, metal, and construction industries. Results by occupation were similar to those by industry. Smoking scores were calculated for various occupations on the basis of a separate population survey in Tianjin. Smoking cannot explain the elevated odds ratios in males, while among females a strong correlation was observed between smoking scores and lung cancer odds ratios, suggesting a confounding effect.

Risk factors associated with oesophageal cancer in Bulawayo, Zimbabwe

This report presents information on risk factors for oesophageal cancer in Bulawayo, Zimbabwe. The data analysed were from the Cancer Registry of Bulawayo for the years 1963-77, when all registered patients were interviewed using a standard questionnaire. The age-standardised incidence rates in the urban population of Bulawayo in the first 10 year period were 58.6 per 100,000 in men and 8.1 in women. The distribution of risk factors was assessed in 881 oesophageal cancer cases (826 male, 55 female) and a control group comprising other non-tobacco- and non-alcohol-related cancer (5238) cases. There was a marked geographical gradient in risk in both sexes, which remained after adjustment for lifestyle variables. In men tobacco smoking was significantly associated with risk of oesophageal cancer, with the relative risk rising to 5.7 among smokers of 15 or more g day-1; this effect is independent of alcohol drinking. Among women who had ever smoked tobacco, the relative risk was 4.0 compared with those who had never smoked. Alcohol intake showed no independent effect on risk. Low socioeconomic status [odds ratio (OR) = 1.5; confidence interval (CI) = 1.0-2.1] and working as a miner (OR = 2.5; CI = 1.5-4.2) conferred increased risks in comparison with men of high socioeconomic status.

Cancer incidence in Thailand, 1988-1991

Results from three cancer registries (Chiang Mai, Khon Kaen, and Songkhla) in different regions of Thailand and from a cancer survey in the population of Bangkok during the years 1988-1991 are presented, together with an estimate of the incidence of cancer for the country as a whole. Overall, liver cancer is the most frequent malignancy, but there are large regional differences in incidence and in histological type, with very high rates of cholangiocarcinoma in the northeast (associated with endemic opisthorchiasis) but a more even distribution of hepatocellular carcinoma. Lung cancer is second in frequency, with the highest rates in northern Thailand, where the incidence in women (Age Standardized Rate, 37.4 per 100,000) is among the highest in the world. A link with tobacco smoking is suggested by similarly raised rates, especially in women, for cancers of the larynx and pancreas. Cervical cancer is the most common malignancy in women, with relatively little regional variation in risk, while the incidence of breast cancer is low. Other cancer sites showing moderately increased rates include the lip and oral cavity, particularly in females from the north and northeast, where the chewing of betel nut remains common among older generations, nasopharyngeal cancer, carcinoma of the esophagus in the southern region, and penile cancer, especially in the north and northeast. Previous studies which have investigated the etiological factors underlying these patterns are reviewed, and the implications for future research and for national cancer control policies are discussed.

Patterns of cigarette sales and lung cancer mortality in some central and eastern European countries, 1960-1989

BACKGROUND

Remarkable increases in lung cancer risk recently have been observed in the Central and Eastern European (CEE) area. This study examines the patterns of lung cancer mortality rates and cigarette sales in 1960-1989 in seven CEE countries with a total population of 97.5 million and 43,000 deaths from lung cancer in the last year under study.

METHODS

Trends in cigarette sales and mortality rates from lung cancer in seven CEE countries were compared for the years 1960-1989.

RESULTS

Among males, recent lung cancer death rates were the highest in Europe, and trends by country largely reflected the varied prevalence and duration of smoking in previous decades. For females, lung cancer mortality rates were much lower, although there were exponential rate increases. In the more recent birth cohorts, there were some declines in mortality rates among males, but not among females.

CONCLUSIONS

The rising cigarette consumption through the 1960s, 1970s, and, in some countries, the 1980s is accompanied in most of the countries by rising lung cancer mortality rates for young adults. This increasing cigarette consumption will determine future trends in lung cancer, which will increase well beyond the turn of the century and will continue longer for females than for males. This outlook underlines the urgent need for comprehensive lung cancer prevention with the concerted control of smoking as a priority. The role of cofactors and their interaction with smoking deserve further exploration.

Cancer survival in Khon Kaen Province, Thailand

Thailand is one of the few developing countries for which population-based cancer survival data are available. Using clinical follow-up information and reply-paid postal enquiries, 10,333 residents of Khon Kaen province registered with cancer in the period 1985-1992 were followed-up to the end of 1993. The sites of the most common cancers in the province were liver (5-year relative survival rate 9.2%), cervix (60.1%), lung (15.4%), breast (48.1%) and large bowel (41.9%). Results for Khon Kaen were compared with age-standardized survival data for the US and Scotland. Survival was consistently higher for US whites compared to Khon Kaen residents for those cancers whose prognosis is associated with early diagnosis (breast, cervix and large bowel) or the availability of intensive therapy (leukaemia and lymphoma). The main implication of these results for cancer control in Thailand is that the interventions of greatest potential benefit are those designed to promote early detection. More than one-third of all cancers in Thailand are liver tumours: primary prevention through control of hepatitis-B infection and liver fluke infestation is the only effective strategy for their control.

Cancer mortality in Italian migrants and their offspring in Canada

Studies on the offspring of migrants provide important information on the contribution of environmental and genetic factors in the etiology of various cancers. The aim of the present study is to analyze the cancer risk in Italian-migrants (Canadian residents born in Italy) and their offspring compared with the host population. Odds ratios (OR) and 95 percent confidence intervals (CI) by site and birthplace categories (migrants, pure and mixed Italian-parentage Canadians) were calculated by means of a case-control study using the 'other cancer deaths' as controls and taking the host population as the reference category. The study shows that Italian migrants retain a significantly low risk for a series of cancers: colon (OR = 0.9 in males and 0.7 in females); lung (OR = 0.8 in males and 0.5 in females); and breast (OR = 0.9). For all of these sites, risks in the offspring of Italian migrants were not different from those of the host population, with some differences between the genders with respect to cancer of the colon. Stomach cancer presents a significantly high rate in migrants (OR = 1.9 in males and 2.4 in females), consistent with the population of Italy; in their offspring, risks are similar to those in the host population. The risk of cancer in the offspring of migrants is, for many sites, intermediate between the host population and the Canadian residents born in Italy. This finding possibly is related to the larger integration of the offspring than their parents in the cultural and social environment of the host population.

Spectrum of childhood cancers in Malawi 1985-1993

An analysis of seven hundred and ninety one children aged 0.2 to 14 years with confirmed malignant disease recorded by the Malawi National Cancer Registry over a period of 9 years is presented. Childhood cancer constituted 6.9% of all malignancies recorded during the study period. The top ten neoplasms in descending order of frequency were: non-Hodgkin's lymphoma 434 (54.9%), retinoblastoma 89 (11.3%), nephroblastoma 50 (6.3%), epithelial carcinoma 45 (5.7%), Hodgkin's disease 38 (4.8%), soft tissue sarcoma (excluding Kaposi): 34(4.3%), Kaposi's sarcoma 32 (4.0%), malignant tumours (not specified): 20 (2.5%), acute leukaemias 18(2.3%) and osteogenic sarcoma 16 (2.0%). Some differences noted in the pattern of neoplasms in this study from those of developed and developing African countries are discussed. The findings highlight the most common childhood malignancies in Malawi where intense research should be directed so that meaningful and cost effective therapeutic intervention programmes can be planned and developed.

At least one in seven cases of cancer is caused by smoking. Global estimates for 1985

Tobacco smoking is accepted as a major cause of cancers of the lung, larynx, oral cavity and pharynx, oesophagus, pancreas, kidney and bladder. The proportions of these cancers that are due to smoking were estimated for the year 1985 for 24 areas of the world. Fifteen percent--1.1 million new cases per year--of all cancer cases are attributed to cigarette smoking, 25% in men and 4% in women. In developed countries, the tobacco burden is estimated at 16% of all annual incident cases. In developing countries, the corresponding figure is 10%. In total, 85% of the 676,000 cases of lung cancer in men are attributable to tobacco smoking. The highest attributable fractions (AF: 90-93%) are estimated in areas where the habit of cigarette smoking in men has been longest established: North America, Europe, Australia/New Zealand and the former USSR. Among the other 6 cancer sites considered in this analysis, those with the largest fractions of tobacco-related cases are the larynx, mouth and pharynx (excluding nasopharynx) and oesophagus. In regions where males have smoked for several decades, 30 to 40% of all cancers in this sex are attributable to tobacco. Unless tobacco-control efforts in developing countries are strengthened, the massive rise in cigarette consumption over the last few decades will produce a comparable rise in cancer in these countries within the next 20 to 30 years.

Bladder cancer: epidemiology and risk factors in Bulawayo, Zimbabwe

The incidence of bladder cancer, and the importance of some selected risk factors in its etiology, were estimated from the data collected in the cancer registry of Bulawayo, Zimbabwe, during the period 1963-77. Cancer cases were interviewed with a standard questionnaire, and more than 70 percent of these were complete. Incidence rates in the urban population of Bulawayo in the first 10-year period were relatively high, with age standardized rates of 17.9 per 100,000 in men and 9.5 in women. Risk-factor distribution was compared in 680 bladder cancer cases (494 males, 186 females) and a control group comprising other cases with non-tobacco-related cancers (8,201). Seventy-one percent of bladder cancer cases were squamous cell carcinomas. The presence of schistosomiasis, evaluated from past history of bilharzia or hematuria, was associated with a significantly increased risk of bladder cancer in both genders (odds ratio [OR] = 3.9 for men, 5.7 for women), a result reflected in the differing risk by province of residence, which correlated with the prevalence of infection among cancer cases. The proportion of bladder cancer attributable to schistosomiasis was estimated to be 28 percent. Social status, as reflected by education level, also influenced risk (ORs for literate cf illiterate males = 0.6), but tobacco smoking in men had no effect on the risk of squamous cell tumors. For transitional cell carcinomas or adenocarcinomas, there was a nonsignificant increased risk of 2.0 in the highest smoking categories (15 g of tobacco per day), compared with non smokers.

Cancer patterns and risk factors in the African population of southwestern Zimbabwe, 1963-1977

The incidence of cancer and the importance of some selected risk factors in its etiology were estimated from the data collected in the cancer registry of Bulawayo, Zimbabwe, during the period 1963-1977. Cancer cases were interviewed with a standard questionnaire, and more than 71% of these were complete. In men, the most frequent cancer sites were liver, esophagus, and lung, while in women, cervical cancer was the dominant malignant tumor, followed by cancers of the liver, breast, and bladder. Risk factors of cancer cases were estimated by case-control analysis in which other cancers (excluding tobacco-related cancers in men and hormone-related cancers in women) were considered as controls. In men, tobacco smoking was associated with increased risk of lung cancer (odds ratio OR2, 5.2) and esophagus cancer (OR, 5.6) in the highest consumption category (15 g of tobacco per day) compared to nonsmokers. Copper (OR, 1.5), gold (OR, 1.5), and nickel (OR, 2.6) miners had an increased risk of lung cancer, but no increase was found among asbestos miners (OR, 0.7). There was no independent effect of alcohol consumption on the risk of esophagus cancer. The presence of schistosomiasis was associated with a significantly increased risk of bladder cancer (OR, 3.9). The risk of invasive cervical cancer increased with number of children--the estimated odds ratio was 1.8 in women with six or more births--but no consistent association was found for first intercourse. In postmenopausal women, the risk of breast cancer increased with age at first pregnancy (but not in the highly fertile) and decreased with high parity, if age at first pregnancy was 19 or more.

Cancer mortality among Chinese and South-East Asian migrants in France

The cancer risk in migrants from China and South-east Asia (Vietnam, Laos and Cambodia) resident in France has been compared to that observed in the local-born population, using mortality data from the period 1979-1985 and population data from the 1982 French census. Risks were adjusted for important confounding factors such as social standing and area of residence. Compared to local-born, South-east Asian migrants of one sex or both sexes combined have higher risks of cancer of the nasopharynx, stomach, liver, gallbladder, lung (in females only), and cervix. On the other hand, South-east Asian migrants have lower risks of cancer of the oral cavity, other pharynx, colon, rectum, larynx, lung (among males only), bladder, nervous system, breast and prostate. Within this group, the risks are quite similar for Vietnamese, Laotians and Cambodians. Results for Chinese-born migrants are quite similar, for most sites, to those found among South-east Asian migrants, although, because of smaller numbers, few of the estimates are statistically significant. These results are consistent with other studies on Chinese migrants around the world, and with the 3 other previous studies on Vietnamese migrants, in England and Wales, Los Angeles and Australia.

Case-control study of gastric cancer screening in Venezuela

A screening programme for early gastric cancer was introduced in the state of Tachira, Venezuela, in 1980. Screening was performed by photofluorography, using two mobile units. The efficacy of this programme in reducing mortality from stomach cancer was evaluated by means of a case-control study. Cases were 241 individuals who died from stomach cancer in the period 1985-89. Ten live controls per case were drawn from the electoral rolls, matched by sex, age and residence. Exposure to the screening examination of cases and controls was assessed through individual linkage with the programme's centralised database. After the exclusion of examinations occurring within the 6 months preceding the case's diagnosis, the odds ratio (OR) of dying from stomach cancer for those screened was 1.26 (CI 0.83-1.91) and the OR in females was lower than in males: 0.77 (CI 0.33-1.78) and 1.52 (CI 0.94-2.47) respectively. Odds ratios associated with years since last test and number of tests did not differ significantly from 1. These results show the inefficacy of the programme in reducing mortality from gastric cancer in the area. In an attempt to determine whether this result was due to selection bias, an analysis restricted to subjects who had been screened at least once was performed. When examinations occurring after an index date at various intervals before the case's diagnosis were excluded, the screening test appeared to protect from death, although confidence intervals of the odds ratios are large, for example OR = 0.47 (CI 0.24-0.98) when excluding tests within 1 month.

A comparative study of carcinoma of the breast in an African population

In a retrospective study of female breast cancer recorded by the Tanzania Cancer Registry, a total of 1028 cases were notified between 1974 to 1987. This represented 8.1% of all female cancers. Of these, 8.0% were below thirty years of age. The peak prevalence was found in the 35 to 44 year old age group. Both the peak prevalence and the high proportion of patients under thirty years suggest that the majority of breast cancer in Tanzania and also in other sub-Saharan African countries are younger than in the populations of North America and Europe. An attempt is made to determine whether this difference is real or is a statistical aberration based on population epidemiology or culture. Mastectomy, the treatment that is usually offered has severe psychological trauma to these young patients. Therefore, early detection of the disease with a breast conservation procedure is advocated.

Cancer in developing countries

Cancer is a major cause of mortality in developing countries, accounting for 13 percent of the annual deaths in adults. As the population increases and ages, the number of new cases of cancer is expected to increase dramatically. This article presents epidemiologic information on the principal cancers in developing countries and outlines the increasing challenge for the control of cancer in developing countries.

Cancer mortality among Polish migrants to Australia

This paper investigates the risk of cancer in Polish migrants to Australia, and compares the results with earlier studies, as well as with results of studies of Polish migrants in other countries. Poisson regression models were used to estimate the risk of death in Polish migrants, relative to the Australia-born, as well as the relative risk of cancer in Poland compared to the Australia-born. In migrant males, a significantly lower risk was found for oral cavity and pharynx, larynx, melanoma, prostate and Hodgkin's disease, while a significantly elevated risk was found for stomach, liver, pancreas, kidney and thyroid gland. In migrant females, a risk significantly lower than in Australian-born individuals was found for oral cavity, colon, melanoma, breast and non-Hodgkin's lymphoma. Relative risk significantly higher than in Australia-born was detected for stomach, gall bladder, pancreas, cervix uteri, nervous system and thyroid gland. For some of these cancers, the risk in migrants approximates to that of the Australia-born with increasing duration of stay. Thus, there are progressive increases in risk for colon cancer in males, and breast cancer and melanoma in females, and decreases in risk for stomach and bladder cancers in males, and uterine cancers in females.

Overview on small cell lung cancer in the world: industrialized countries, Third World, eastern Europe

Lung cancer cases were abstracted from cancer registries in 20 countries to study the distribution of small cell lung cancer around 1985. The international patterns of small cell lung cancer resemble those of squamous cell tumours, and of lung cancer as a whole. Cigarette smoking and occupational risk factors are more strongly associated with squamous and small cell lung cancers than with adenocarcinoma. Inspection of sex differences and time trends in incidence show some differences which may relate to a higher risk for small cell lung cancer in female smokers than in males, and a less rapid decline in risk on smoking cessation.

International variations in the incidence of childhood soft-tissue sarcomas

In the study of international childhood cancer incidence coordinated by the International Agency for Research on cancer, soft-tissue sarcomas comprised between 4 and 8% of all cancers between 0 and 14 years of age. Among predominantly white populations, the age-standardised annual incidence rate (ASR) for all soft-tissue sarcomas was between 5 and 9 per million. The most common histological subtypes were rhabdomyosarcoma (ASR 4-7 per million) and fibrosarcoma, including other malignant fibromatous tumours (ASR 1-2 per million). In the United States the incidence of rhabdomyosarcoma for black girls was only half that for white girls, while the rates for boys were similar in the two ethnic groups; fibrosarcoma had a higher incidence among black people than white people for both sexes. Throughout most of Asia, soft-tissue sarcomas almost invariably had a total ASR below 6 per million, rhabdomyosarcoma and fibrosarcoma again being the most common histological types. In Africa, incidence rates could not generally be calculated, but there were substantial numbers of registrations for rhabdomyosarcoma and fibrosarcoma. The majority of cases of Kaposi's sarcoma were in African children, and in eastern and southern Africa where Kaposi's sarcoma is endemic among adult men it comprised 25-50% of soft-tissue sarcomas and 2-10% of all childhood cancers; the sex ratio (M/F) was 2.2:1, in contrast to the overwhelming male predominance among adults. Variations between ethnic groups in the incidence of rhabdomyosarcoma and fibrosarcoma, together with their occurrence in a number of heritable syndromes, suggest that genetic predisposition is important in their aetiology. There was little evidence for an environmental aetiology in rhabdomyosarcoma and fibrosarcoma but an infectious agent may be responsible for childhood Kaposi's sarcoma.

Estimates of the worldwide mortality from eighteen major cancers in 1985. Implications for prevention and projections of future burden

This report presents worldwide estimates of annual mortality from all cancers and for 18 specific cancer sites around 1985. Crude and age-standardized mortality rates and numbers of deaths were computed for 24 geographical areas. Of the estimated 5 million deaths from cancer (excluding non-melanoma skin cancer), 56% occurred in developing countries. The most frequent neoplasm is lung cancer, accounting for 22% of cancer deaths in men. Among women breast cancer is the leading malignancy, accounting for 16% and 11% of all cancer deaths in developed and developing countries, respectively. In developing countries, cancer of the cervix uteri ranks first, breast cancer second. The second most frequent cause of death from cancer in both sexes is cancer of the stomach, followed by liver cancer in men and by colon/rectum cancer in women. Cancers of the colon/rectum and prostate maintain a high rank in men living in developed countries, while cancers of the lung, ovary and pancreas occupy similar ranks among women. In developing countries, cancers of the oesophagus and mouth/pharynx follow those previously mentioned in both sexes. If the estimated rates continue to prevail, increases in the numbers of deaths of 20.4% in developed and 18.1% in developing countries are expected by the year 2000, simply as a consequence of demographic trends towards ageing and population growth. Our results provide an indication of the potential impact of preventive practices. It is estimated that 20% of all cancer deaths (1 million) could be prevented by eliminating tobacco smoking. Mortality from cancers of the liver and uterine cervix, both major problems in developing countries, could be substantially reduced by immunization against hepatitis B virus infection and early detection through Pap smears, respectively.

Cancer in the population of Hanoi, Vietnam, 1988-1990

The first results from the population-based cancer registry for the city of Hanoi, in northern Vietnam, are presented. In men, incidence rates are moderate-low with the most common cancers being lung, stomach and liver. Cancer of the penis, reportedly very common in early case series from Vietnam, is now rarely seen. In women, incidence rates are low with the most common cancer, breast cancer, having a recorded incidence similar to that in China. Cervix cancer incidence is very low, which contrasts strongly with hospital series from the south of Vietnam, and of 30 years earlier in Hanoi. The incidence of choriocarcinoma is high, and that of nasopharynx cancer (in both sexes) moderately so; both findings are typical of southeast Asian populations. The incidence rates are coherent with the results from recent studies of Vietnamese migrants in the USA and UK.

Cholangiocarcinoma: epidemiology, mechanisms of carcinogenesis and prevention

Cholangiocarcinoma is a relatively rare cancer; worldwide it accounts for an estimated 15% of liver cancers. In most areas, the etiology is rather obscure, and identified risk factors such as hepatolithiasis, inflammatory bowel disease, and exposure to Thorotrast can account for only a small proportion of cases. In certain areas of southeast and eastern Asia, however, incidence rates are very high, and here there is a strong association with infection with the liver flukes Clonorchis sinensis and Opisthorchis viverrini. The mechanisms of carcinogenesis in O. viverrini infection have been the subject of considerable research; it seems that the presence of parasites induces DNA damage and mutations as a consequence of the formation of carcinogens/free radicals and of cellular proliferation of the intrahepatic bile duct epithelium. Preventive strategies in areas endemic for liver flukes appear straightforward, but breaking the cycle of infection has proved difficult in practice.

Estimates of the worldwide incidence of eighteen major cancers in 1985

The annual incidence rates (crude and age-standardized) and numbers of new cases of 18 different cancers have been estimated for the year 1985 in 24 areas of the world. The total number of new cancer cases (excluding non-melanoma skin cancer) was 7.6 million, 52% of which occur in developing countries. The most common cancer in the world today is lung cancer, accounting for 17.6% of cancers of men worldwide, and 22% of cancers in men in the developed countries. Stomach cancer is now second in frequency (it was slightly more common than lung cancer in 1980) and breast cancer--by far the most important cancer of women (19.1% of the total)--is third. There are very large differences in the relative importance of the different cancers by world area. The major cancers of developed countries (other than the 3 already named) are cancers of the colon-rectum and prostate, and, in developing countries, cancers of the cervix uteri, mouth and pharynx, liver and oesophagus. The implications of these patterns for cancer control, and specifically prevention, are discussed. Tobacco smoking and chewing are almost certainly the major preventable causes of cancer today.

Cancer in Kampala, Uganda, in 1989-91: changes in incidence in the era of AIDS

Re-establishment of the cancer registry in Kyadondo County, Uganda, has allowed estimation of incidence rates for the period September 1989 to December 1991. The results are compared with earlier data from the same area, and from other African cancer registries. The most striking feature is the emergence of Kaposi's sarcoma as the leading cancer in males (almost half of all registered cases) and the second most frequent (17.9%) in females. This parallels the evolution of the epidemic of AIDS. There were also marked increases in the incidence of both oesophageal and prostatic carcinoma, while the incidence of cancer of the penis and the urinary bladder declined, possibly as a result of improved standards of hygiene. In females, the incidence of cancer of the cervix has more than doubled since the 1950s, and is now among the highest recorded in the African continent.

International variations in the incidence of childhood bone tumours

Bone cancers comprise about 5% of childhood neoplasms. Osteosarcoma, the most common sub-type, shows a somewhat irregular geographic pattern of incidence, with low rates in some Asian (Indian, Japanese, Chinese) and Latin American populations. Incidence is similar in the sexes and rises steeply with age, accompanied by an increasing proportion of tumours localized in the long bones of the legs. Rates in the USA are higher in blacks than in whites, as a result of a higher incidence at ages 10 to 14 and of tumours of the leg bones. The descriptive epidemiology is consistent with early observations linking risk to the amount of bone growth. Ewing's sarcoma is rare in black populations (USA and Africa) and in eastern Asia. Compared with osteosarcoma, a lower percentage of tumours is localized to the long bones, and incidence rises less steeply with age and is accompanied by an increasing proportion of pelvic tumours. Chondrosarcoma is a rare cancer in children (less than 5% of bone cancers), with an age distribution similar to that of osteosarcoma and a sub-site distribution resembling that of Ewing's sarcoma. Little is known of the aetiology of these tumours; there is clearly a strong genetic predisposition in Ewing's sarcoma but, although the proportion of osteosarcoma cases of genetic origin seems to be small, environmental determinants so far suspected can account for only a small fraction of the total cases.

Education and mortality from cancer in São Paulo, Brazil

This study investigated social class differentials in cancer mortality in São Paulo county, Brazil, for the period 1978 to 1982. A measure of socioeconomic status based on education was used, and cancer risk by level of education was estimated by a case-control approach in which other cancers were considered as controls. For most cancers, the socioeconomic differences in risk were similar to those found in western Europe and North America. For lung cancer, however, the highest risk was observed in men and women with the most education. Other cancers related to tobacco--cancer of the larynx, pharynx, and esophagus--showed a negative association with education. The differences between social classes in consumption habits of alcohol and maté and the use of black tobacco are probably responsible for these contrasting patterns. For breast and cervix uteri cancer the social class patterns were similar to those found in developed countries--a positive relationship for breast and a negative one for cervix uteri cancer. The magnitude of the differences observed between social classes for these cancers was frequently greater in South America than in the United States or western Europe.

Childhood leukaemia following the Chernobyl accident: the European Childhood Leukaemia-Lymphoma Incidence Study (ECLIS)

The objective of the European Childhood Leukaemia-Lymphoma Incidence Study (ECLIS) is to investigate trends in incidence rates of childhood leukaemia and lymphoma in Europe, in relation to the exposure to radiation which resulted from the accident at the Chernobyl nuclear power plant in April 1986. In this first report, the incidence of leukaemia in children aged 0-14 is presented from cancer registries in 20 European countries for the period 1980-1988. Risk of leukaemia in 1987-1988 (8-32 months post-accident) relative to that before 1986, is compared with estimated average dose of radiation received by the population in 30 geographic areas. The observed changes in incidence do not relate to exposure. The period of follow-up is so far rather brief, and the study is planned to continue for at least 10 years.

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.

International variations in the incidence of neuroblastoma

The International Agency for Research on Cancer has coordinated a worldwide study of childhood cancer incidence, with data from over 50 countries. We present here the results for neuroblastoma. In predominantly white Caucasian populations the age-standardized rate was 7-12 per million, and 6-10% of all childhood cancers were neuroblastomas. Rates were highest in the first year of life (25-50 per million, 30% of total neuroblastoma incidence), and decreased with age to 15-20 per million (50% of the total) at age 1-4, 2-4 per million (15%) at 5-9 and 1-1.5 per million (5%) at 10-14. In the United States, black children had an incidence of 8.5 per million compared with 11.5 among Whites; Blacks tended to be older than Whites at diagnosis. The highest rate in Africa was in Bulawayo, Zimbabwe (8.0 per million) and the lowest in West Nile, Uganda, with no cases registered. Incidence in Israel was similar to that in many white populations, with Jews having a particularly high rate. In other parts of West Asia neuroblastoma had a low relative frequency, suggesting that incidence is low. Rates were also low throughout much of southern and eastern Asia, including India and China. Incidence in Japan was somewhat higher, though less than in Western countries, with the deficit most pronounced in the first year of life; these data relate to the period before mass screening of infants for neuroblastoma in the regions concerned. Incidence was generally higher in regions and among ethnic groups enjoying a higher standard of living, though previous studies within single countries had suggested that neuroblastoma is more common among less affluent groups. Blacks in Africa and the United States may have a weaker genetic predisposition to neuroblastoma, but some of the deficit in many developing countries is likely to be due to under-diagnosis.

The natural history of lung cancer estimated from the results of a randomized trial of screening

The results from a randomized controlled trial of screening for lung cancer in Czechoslovakia have been used to estimate parameters of the natural history, using a model to simulate the disease process and the effects of screening. The results suggest that the period before clinical presentation during which lesions can be detected by screening is very short (seven to eight months). This implies that to detect three-quarters of all lung cancers by screening, two examinations per year are necessary, and that such a program would advance diagnosis by six months if there were complete participation. The results of the trial itself suggest that the benefit, in terms of a reduction in mortality from lung cancer, is likely to be very small.

Cancer in migrants to Argentina

Mortality rates from different cancers in migrants to Argentina from 11 individual countries and 6 groups of countries were compared with those in the Argentina-born population and in their countries of origin. Almost all countries of origin had higher mortality rates from gastric cancer than Argentina, but the risk declines in migrants, and for European migrants becomes similar to that of the Argentina-born. In contrast, mortality from oesophageal cancer is significantly lower in European countries than in Argentina. For cancer of the colon and breast, most countries have lower mortality rates than the Argentina-born, the exceptions being Uruguay and Germany, and migrants demonstrate a convergence of risk towards that of Argentina-born. These results suggest that migrants to Argentina undergo changes in some environmental exposure, probably dietary, which give rise to substantial alterations in cancer risk within their lifespan.

The role of infection by Opisthorchis viverrini, hepatitis B virus, and aflatoxin exposure in the etiology of liver cancer in Thailand. A correlation study

The incidence of the two principle types of liver cancer (hepatocellular carcinoma and cholangiocarcinoma) in five different areas of Thailand was compared with the prevalence of exposure to the main risk factors in samples of the population. Cholangiocarcinoma showed striking variations in incidence, which correlated closely with markers of exposure to the liver fluke, Opisthorchis viverrini. However, there was little geographic variation in incidence of hepatocellular carcinoma or in prevalence of the major risk factors (chronic carriage of hepatitis B virus and exposure to aflatoxin), and apparently there was little relationship between them.

Ethnicity and cancer risk in São Paulo, Brazil

Data from the São Paulo Cancer Registry (Brazil) for the period 1969-1974 are used to investigate ethnic differentials in cancer risk. Risks for specific cancers were estimated for mulattos and blacks relative to whites, using a case-control approach with other cancers as controls. For both sexes, blacks and mulattos are at higher risk than whites for cancer of the esophagus, stomach, and liver and for myeloma; for prostate cancer in males; and for gall bladder, pancreas, and cervix uteri cancers in females. Blacks and mulattos are at lower risk than whites for cancer of the colon, lung, larynx (males only), bladder, bone, testis, breast, and corpus uteri and for melanoma and leukemia. Except for lung and colon cancers, for which life-style habits are the main risk factors, these ethnic differences are similar to those observed in the United States.

Cancer risks related to electricity production

The International Agency for Research on Cancer has previously evaluated the cancer risks associated with fossil fuel-based industrial processes such as coal gastification and coke production, substances and mixtures such as coal tars, coal tar pitch and mineral oils, and a number of substances emitted from fossil-fuelled plants such as benzo[a]pyrene and other polycyclic aromatic hydrocarbons, arsenic, beryllium, cadmium, chromium, nickel, lead and formaldehyde. Based on these evaluations and other evidence from the literature, the carcinogenic risks to the general population and occupational groups from the fossil fuel cycle, the nuclear fuel cycle and renewable cycles are reviewed. Cancer risks from waste disposal, accidents and misuses, and electricity distribution are also considered. No cycle appears to be totally free from cancer risk, but the quantification of the effects of such exposures (in particular of those involving potential exposure to large amounts of carcinogens, such as coal, oil and nuclear) requires the application of methods which are subject to considerable margins of error. Uncertainties due to inadequate data and unconfirmed assumptions are discussed. Cancer risks related to the operation of renewable energy sources are negligible, although there may be some risks from construction of such installations. The elements of knowledge at our disposal do not encourage any attempt toward a quantitative comparative risk assessment. However, even in the absence of an accurate quantification of risk, qualitative indication of carcinogenic hazards should lead to preventive measures.

Cancer incidence in Western Samoa

This report presents the first data on cancer incidence in Western Samoa, which has one of the largest Polynesian communities in the world. Incidence estimates are based on a systematic retrospective survey of cancer cases identified in the laboratory of pathology, and from hospital records, for the period January 1980 to June 1988. The overall incidence rates are low in both sexes (age-standardized incidence rates are 93.7 for males and 95.7 per 100,000 for females). Although cases may have been missed, it seems likely that incidence rates among Samoans are substantially lower than those recorded in Polynesian populations elsewhere. It is notable that cancers related to tobacco are responsible for less than 17% of all cancers in males, compared to more than 30% in other Polynesians. Stomach cancer remains the most common cancer in males. In females, breast and cervix are equally common and make up almost 40% of all cancers. Liver cancer occurs more commonly in males, and the rates are slightly lower than those of other Polynesians. The high incidence of thyroid cancer seen in some Pacific Island populations is not seen among Samoans.

Liver cancer in Thailand. II. A case-control study of hepatocellular carcinoma

Potential risk factors for hepatocellular carcinoma were investigated in a case-control study among inhabitants of north east Thailand. Sixty-five cases from 3 hospitals, with matched controls, were included. Infection with hepatitis-B virus was the major risk factor-chronic carriers of HB surface antigen had an estimated relative risk of 15.2. Infection with hepatitis-C virus appeared to be rare. No increase in risk was found with recent aflatoxin intake, as estimated by consumption of possibly contaminated foods, or by measuring aflatoxin-albumin adducts in serum. Regular use of alcohol (2 or more glasses of spirits per week) was associated with a non-significant elevation in risk (o.r. = 3.4, 95% c.i. 0.8-14.6), but the number of regular drinkers in the population was small. The meaning of an apparent protection conferred by certain food items is uncertain, but a possible role of betel nut in the aetiology deserves further investigation.

Liver cancer in Thailand. I. A case-control study of cholangiocarcinoma

Potential risk factors for cholangiocarcinoma were investigated in a case-control study among inhabitants of north-east Thailand, which included 103 cases from 3 hospitals, with age- and sex-matched controls. A clear association with past or present infection with Opisthorchis viverrini, as indicated by raised serum antibodies, was found (o.r. 5.0), and at least two-thirds of cases can be attributed to this cause. The results suggest that males may be at higher risk than females. There was no association with hepatitis B infection, with aflatoxin intake as estimated from albumin adducts in serum or with any particular dietary patterns. Alcohol consumption was very low in the population, and the risk associated with regular drinking was non-significant. Regular users of betel nut-predominantly female-had a high risk (o.r. 6.4), a possible mechanism being through their increased exposure to nitrosamines.

Geographical patterns of cancer mortality in Argentina

Mortality rates in 1980, for the major cancer sites, are presented for Argentina as a whole, and for the 22 provinces, the capital city, and the southern territories. In comparison with other countries, national mortality rates are high for oesophageal cancer and cancer of the larynx, and moderately elevated for cancers of the lung, colon, breast, and bladder in males. The rates of tobacco-related cancers (lung, bladder and larynx) were much higher in males than females, and in males showed similar geographical patterns. In females, breast cancer rates by province showed a positive correlation with those for cancer of the colon, and a negative correlation with cervical cancer. There were marked geographical variations, quite different in the two sexes, in the mortality from oesophageal cancer. It is suggested that, although some of these variations within Argentina may be related to ethnic differences and patterns of migration from neighbouring countries, for the majority the explanations must lie in different exposures to environmental of lifestyle factors, such as diet.

International variations in the incidence of childhood renal tumours

The International Agency for Research on Cancer has coordinated a worldwide study of childhood cancer incidence, with data from over 50 countries. We present here the results on renal tumours. Wilms' tumour was the most common malignant kidney tumour in all regions. It is sometimes considered to be an 'index cancer of childhood' but it is clear from the present study that there is at least a threefold difference in incidence between the age-standardised annual rates of over 10 per million in the Black populations in the United States and Nigeria and those of around three per million in several East Asian populations. In White Caucasian populations, Wilms' tumour had an annual incidence of 6-9 per million, accounting for 5-7% of all childhood cancer. It was almost everywhere equally common in boys and girls, but the sex ratio in East Asia was M/F = 1.4:1. Age distributions were similar among White Caucasian and Black populations, with the peak incidence in the second year of life. In East Asia, however, 25-40% of the total incidence occurred in infants aged under 1 year, compared with around 15% in many Western series. Other studies have shown that, in the United States, Wilms' tumour has a lower incidence among Asian children than among Whites or Blacks and tends to occur at a younger age. The variation in patterns of incidence of Wilms' tumour along ethnic rather than geographical lines suggests that genetic predisposition is important in its aetiology. Renal carcinoma in childhood is rare throughout the world, with little sign of international variation. It accounted for a higher proportion of childhood renal tumours in East Asia but this was attributable to the lower incidence of Wilms' tumour in that region.

Cancer in migrants to Uruguay

Mortality rates from different cancers in the principal groups of migrants to Uruguay are compared with those in their countries of origin (Argentina, Brazil, Italy and Spain) and in the Uruguay-born population. Oesophageal cancer is very common in Uruguay and European-born populations, initially at low risk, appear to acquire rather higher rates after migration. For most migrants, the mortality from cancers of the breast, colon-rectum, corpus uteri and prostate is closer to the moderately elevated rates of Uruguay than those in their countries of origin. The results suggest that migrants to Uruguay undergo changes in some important environmental exposures, probably dietary, which give rise to substantial alterations in cancer risk within their lifespan.

International variations in the incidence of childhood lymphomas

The International Agency for Research on Cancer has coordinated a worldwide study of childhood cancer incidence, with data provided by contributors from over 50 countries. We present here the results on lymphomas from this study and other sources. Hodgkin's disease had a relatively high incidence in North Africa and West Asia and a low incidence throughout East Asia. In populations of predominantly European origin, the highest rates tended to be in warmer countries of lower latitude. In industrialised Western countries, the incidence increased steeply with age and was low in childhood compared with that in young adults whereas elsewhere the increase in incidence between childhood and adults aged 20-34 was much less marked. The age-distribution of Hodgkin's disease in childhood appears to be related to levels of socio-economic development but the total incidence seems to be determined more by ethnic and environmental factors. The highest incidence of Burkitt's lymphoma occurred in tropical Africa and Papua New Guinea. Elsewhere, Burkitt's lymphoma was rare, though the incidence was higher in Spain, North Africa and the Middle East than in other areas. In most Western countries, a third of all non-Hodgkin lymphomas may be Burkitt's. There was no consistent pattern in the incidence of other non-Hodgkin lymphomas except for a tendency towards higher rates around the Mediterranean and in some Latin American registries.

Log-linear models for cancer risk among migrants

Epidemiological studies of migrants have played an important role in separating the environmental and genetic components of cancer aetiology. The statistical analyses of these studies have typically involved calculating age- and sex-adjusted rates by country of birth. We describe methods which permit the effect of duration of residence in the host country to be estimated after adjusting for other temporal effects such as age, and period or cohort. The methods, which are based on log-linear modelling, can also be applied in a case-control manner if appropriate denominator populations are unavailable. Examples are given in which the more traditional methods of analysis may have yielded misleading results.

Cancer in Mali, 1987-1988

Results from the population cancer registry in Bamako, Mali, for the years 1987 and 1988, are presented. The age-standardized incidence for all cancers is high compared with rates reported elsewhere in West Africa (119.6 per 10(5) in males and 88.3 per 10(5) in females), but the leading cancers in each sex are the same (liver cancer in males, cervix cancer in females). The incidence of stomach cancer is the highest recorded in Africa, while rates for lung cancer, although low, exceed those in earlier series from registries in the region.

Cancer in Jewish migrants to Israel

Data on the incidence of 15 cancers in the Jewish population of Israel from the period 1961-1981 have been studied with emphasis on the risk of disease in relation to birthplace, calendar time, and duration of residence in Israel. The results show wide variations in incidence by birthplace, from less than 2-fold for pancreatic cancer to a 40-fold difference for oesophageal cancer in females; the reasons for these are often little understood. The potential importance of environmental agents in aetiology for different migrant groups is discussed in relation to the size and rapidity of changes in risk related to the duration of residence in Israel.

Lack of benefit from semi-annual screening for cancer of the lung: follow-up report of a randomized controlled trial on a population of high-risk males in Czechoslovakia

Cigarette-smoking males (6,364), aged 40-64, were randomized into an intervention group which received 6-monthly screening by chest X-ray and sputum cytology, and a control group which received no asymptomatic investigation. After 3 years, both groups entered a follow-up period during which they received annual chest X-rays. Lung cancer cases detected by screening were identified at an earlier stage, more often resectable, and had a significantly better survival than "interval" cases diagnosed mainly because of symptoms. Comparison of the 2 groups showed a higher incidence of lung cancer in the intervention group, despite the follow-up period when both groups received annual examinations. There was no significant difference in mortality between the 2 groups.

Cancers of the breast, endometrium and ovary: geographic correlations

Patterns of incidence of breast, endometrial and ovarian cancer show strong similarities in both international and inter-regional comparisons, similarities readily confirmed by the calculation of coefficients of correlation. Migrant studies suggest that environmental factors are more important than genetic differences between populations. Correlation studies have shown that dietary factors can explain much of the international variation, and most suspicion has fallen on dietary fat. Differences in fertility between populations also correlate with the variations in incidence. For breast cancer, the latter may be an important determinant of variation within countries in the pre-menopausal age group, with dietary differences accounting for variations in post-menopausal rates internationally. There is scope for improving upon earlier studies, and for investigating the relative contributions of diet and fertility to the geographic patterns of endometrial and ovarian cancers.