International lung cancer trends by histologic type: male:female differences diminishing and adenocarcinoma rates rising

Lung cancer rates have peaked among men in many areas of the world, but rates among women continue to rise. Most lung cancers are squamous cell carcinoma, small cell carcinoma, or adenocarcinoma; trends vary according to type. We compiled population-based morphology-specific incidence data from registries contributing to the International Agency for Research on Cancer (IARC) databases. Unspecified cancers and carcinomas were reallocated based on a registry, time period, sex and age group-specific basis. Where available, data from several registries within a country were pooled for analysis. Rates per 100,000 person-years for 1980-1982 to 1995-1997 were age-adjusted by the direct method using the world standard. Squamous cell carcinoma rates among males declined 30% or more in North America and some European countries while changing less dramatically in other areas; small cell carcinoma rates decreased less rapidly. Squamous and small cell carcinoma rates among females generally rose, with the increases especially pronounced in the Netherlands and Norway. In contrast, adenocarcinoma rates rose among males and females in virtually all areas, with the increases among males exceeding 50% in many areas of Europe; among females, rates also rose rapidly and more than doubled in Norway, Italy and France. Rates of all lung cancer types among women and adenocarcinoma among men continue to rise despite declining cigarette use in many Western countries and shifts to filtered/low-tar cigarettes. Renewed efforts toward cessation and prevention are mandatory to curb the prevalence of cigarette smoking and to reduce lung cancer rates eventually.

Tobacco associated mortality in Mumbai (Bombay) India. Results of the Bombay Cohort Study

BACKGROUND

Little is known about the excess mortality from forms of tobacco use other than cigarette smoking that are widely prevalent in India, such as bidi smoking and the various forms of smokeless tobacco use. We report on absolute and relative risks of mortality among various kinds of ever tobacco users vs never-users in the city of Mumbai, India.

METHODS

Using the Mumbai voters' list as the selection frame, 99 570 individuals aged > or = 35 years were interviewed at their homes during 1992-94. At active follow-up (during 1997-99) after 5.5 years, 97 244 (97.7%) were traced. Among these, 7531 deaths (4119 men, 3412 women) were recorded, of which 89% died within study area. It was possible to abstract cause of death information from the records of the municipal corporation for 5470 deaths. These were coded using ICD 10.

RESULTS

The adjusted relative risk was 1.37 (95% CI 1.23-1.53) for (men) cigarette smokers and 1.64 (95% CI 1.47-1.81) for bidi smokers, with a significant dose-response relationship for number of bidis or cigarettes smoked. Women were essentially smokeless tobacco users; the adjusted relative risk was 1.25 (95% CI 1.15-1.35). The risk of deaths from respiratory diseases (RR 2.12, 95% CI 1.57-2.87), tuberculosis (RR 2.30, 95% CI 1.68-3.15), and neoplasms (RR 2.60, 95% CI 1.78-3.80) were significantly high in male smokers than never tobacco users.

CONCLUSIONS

Bidi is no less hazardous than cigarette smoking, and smokeless tobacco use may also result in significantly increased mortality.

A prospective study of diet, lifestyle, and genetic factors and the risk of cancer in Khon Kaen Province, northeast Thailand: description of the cohort

Cohort studies are the preferred design in observational epidemiology, but few involving the general population have been performed in Asia, and most concern affluent urban populations. The Khon Kaen study has recruited about 25,000 subjects, aged mainly 35-64, from villages in the relatively underdeveloped north-east of Thailand. All subjects underwent simple physical examination, completed an interviewer-administered questionnaire (including sections on lifestyle, habits, and diet) and donated specimens of blood, which were processed and stored in a biological bank at -20 degrees C. Female subjects (about 16,500) were offered screening by Pap smear, and specimens of cells from the cervix were stored at -20 degrees C. This paper describes the methodology of the study, and the characteristics of the participants. Almost all subjects are peasant farmers, with low annual income and body mass, although 14.6% of women had a BMI in the obese range (>30 kg/m(2)). Smoking was common among men (78% regular smokers, most of whom used home-produced cigarettes), but rare among women. Fertility levels were relatively high, with a more than half the women having four or more live births. 23.4% of subjects were infected with the liver fluke Opisthorchis viverrini, known to be highly endemic in this region. Follow-up of the cohort is by record-linkage to the provincial cancer registry. By 2003, 762 cancer cases had occurred, the most common being cancers of the liver (363 cases) and cervix uteri (44 cases). The antecedents of these cancers are being investigated using a nested case-control approach. The cohort will yield increasing numbers of cancers for study in the next decade, giving important information on the relative importance of dietary and lifestyle factors in a rural population, undergoing gradual transition to a more westernised lifestyle.

Cancer survival in Kampala, Uganda

Epidemiological data on the occurrence of cancer in sub-Saharan Africa are sparse, and population-based cancer survival data are even more difficult to obtain due to various logistic difficulties. The population-based Cancer Registry of Kampala, Uganda, has followed up the vital status of all registered cancer patients with one of the 14 most common forms of cancer, who were diagnosed and registered between 1993 and 1997 in the study area. We report 5-year absolute and relative survival estimates of the Ugandan patients and compare them with those of black American patients diagnosed in the same years and included in the SEER Program of the United States. In general, the prognosis of cancer patients in Uganda was very poor. Differences in survival between the two patient populations were particularly dramatic for those cancer types for which early diagnosis and effective treatment is possible. For example, 5-year relative survival was as low as 8.3% for colorectal cancer and 17.7% for cervical cancer in Uganda, compared with 54.2 and 63.9%, respectively, for black American patients. The collection of good-quality follow-up data was possible in the African environment. The very poor prognosis of Ugandan patients is most likely explained by the lack of access to early diagnosis and treatment options in the country. On the policy level, the results underscore the importance of the consistent application of the national cancer control programme guidelines as outlined by the World Health Organization.

Global cancer statistics, 2002

Estimates of the worldwide incidence, mortality and prevalence of 26 cancers in the year 2002 are now available in the GLOBOCAN series of the International Agency for Research on Cancer. The results are presented here in summary form, including the geographic variation between 20 large "areas" of the world. Overall, there were 10.9 million new cases, 6.7 million deaths, and 24.6 million persons alive with cancer (within three years of diagnosis). The most commonly diagnosed cancers are lung (1.35 million), breast (1.15 million), and colorectal (1 million); the most common causes of cancer death are lung cancer (1.18 million deaths), stomach cancer (700,000 deaths), and liver cancer (598,000 deaths). The most prevalent cancer in the world is breast cancer (4.4 million survivors up to 5 years following diagnosis). There are striking variations in the risk of different cancers by geographic area. Most of the international variation is due to exposure to known or suspected risk factors related to lifestyle or environment, and provides a clear challenge to prevention.

Global cancer statistics, 2002

Estimates of the worldwide incidence, mortality and prevalence of 26 cancers in the year 2002 are now available in the GLOBOCAN series of the International Agency for Research on Cancer. The results are presented here in summary form, including the geographic variation between 20 large "areas" of the world. Overall, there were 10.9 million new cases, 6.7 million deaths, and 24.6 million persons alive with cancer (within three years of diagnosis). The most commonly diagnosed cancers are lung (1.35 million), breast (1.15 million), and colorectal (1 million); the most common causes of cancer death are lung cancer (1.18 million deaths), stomach cancer (700,000 deaths), and liver cancer (598,000 deaths). The most prevalent cancer in the world is breast cancer (4.4 million survivors up to 5 years following diagnosis). There are striking variations in the risk of different cancers by geographic area. Most of the international variation is due to exposure to known or suspected risk factors related to lifestyle or environment, and provides a clear challenge to prevention.

Global cancer statistics, 2002

Estimates of the worldwide incidence, mortality and prevalence of 26 cancers in the year 2002 are now available in the GLOBOCAN series of the International Agency for Research on Cancer. The results are presented here in summary form, including the geographic variation between 20 large "areas" of the world. Overall, there were 10.9 million new cases, 6.7 million deaths, and 24.6 million persons alive with cancer (within three years of diagnosis). The most commonly diagnosed cancers are lung (1.35 million), breast (1.15 million), and colorectal (1 million); the most common causes of cancer death are lung cancer (1.18 million deaths), stomach cancer (700,000 deaths), and liver cancer (598,000 deaths). The most prevalent cancer in the world is breast cancer (4.4 million survivors up to 5 years following diagnosis). There are striking variations in the risk of different cancers by geographic area. Most of the international variation is due to exposure to known or suspected risk factors related to lifestyle or environment, and provides a clear challenge to prevention.

Consistency of cytology diagnosis for cervical cancer between two laboratories

The principal approach to the prevention of cancer of the cervix uteri has been through screening programmes, using the cervical smear (Pap test) to detect precursor lesions. The sensitivity and specificity of Pap smears depend on the skill of the observer in recognizing and classifying a variety of cellular abnormalities. We have studied the reproducibility of cytological diagnosis, according the Bethesda classification, made by cytologists in Khon Kaen, north-east Thailand, and in Helsinki, Finland, on smears taken from rural women undergoing screening during 1994-2001. A total of 313 slides were reviewed. The prevalence of abnormalities was relatively high, since the series included smears judged abnormal in Khon Kaen or from women who developed cancer during follow-up, as well as a group whose smears were negative. In general, the reviewing cytologist in Finland evaluated more slides as abnormal than in the initial report. The level of agreement between the two observers was evaluated by calculating the coefficient of concordance (Kappa). The kappa score depended upon the degree of detail in the diagnosis; it was 0.43 for the presence or not of an epithelial abnormality (the General Categorization of the Bethesda system), and rather higher (0.5) for separating low grade from high grade (HSIL or worse) abnormalities or glandular lesions. Agreement was only fair (0.37) when the more detailed Bethesda categories (seven) were used. The reproducibility of cervical cytology evaluations is critical to the success of screening programmes, and in this programme in a moderate-high risk population of women in rural Thailand, we found that agreement between skilled observers, at the level of tests requiring diagnostic follow-up or not, was only moderate. The women in this study are being traced to evaluate the true sensitivity of screening in terms of the lesions found on histology, during a prolonged follow up of 4 or more years.

Global cancer statistics, 2002

Estimates of the worldwide incidence, mortality and prevalence of 26 cancers in the year 2002 are now available in the GLOBOCAN series of the International Agency for Research on Cancer. The results are presented here in summary form, including the geographic variation between 20 large "areas" of the world. Overall, there were 10.9 million new cases, 6.7 million deaths, and 24.6 million persons alive with cancer (within three years of diagnosis). The most commonly diagnosed cancers are lung (1.35 million), breast (1.15 million), and colorectal (1 million); the most common causes of cancer death are lung cancer (1.18 million deaths), stomach cancer (700,000 deaths), and liver cancer (598,000 deaths). The most prevalent cancer in the world is breast cancer (4.4 million survivors up to 5 years following diagnosis). There are striking variations in the risk of different cancers by geographic area. Most of the international variation is due to exposure to known or suspected risk factors related to lifestyle or environment, and provides a clear challenge to prevention.

Global cancer statistics, 2002

Estimates of the worldwide incidence, mortality and prevalence of 26 cancers in the year 2002 are now available in the GLOBOCAN series of the International Agency for Research on Cancer. The results are presented here in summary form, including the geographic variation between 20 large "areas" of the world. Overall, there were 10.9 million new cases, 6.7 million deaths, and 24.6 million persons alive with cancer (within three years of diagnosis). The most commonly diagnosed cancers are lung (1.35 million), breast (1.15 million), and colorectal (1 million); the most common causes of cancer death are lung cancer (1.18 million deaths), stomach cancer (700,000 deaths), and liver cancer (598,000 deaths). The most prevalent cancer in the world is breast cancer (4.4 million survivors up to 5 years following diagnosis). There are striking variations in the risk of different cancers by geographic area. Most of the international variation is due to exposure to known or suspected risk factors related to lifestyle or environment, and provides a clear challenge to prevention.

Trends in Cervical Squamous Cell Carcinoma Incidence in 13 European Countries: Changing Risk and the Effects of Screening

Despite there being sufficient evidence for the effectiveness of screening by cytology in preventing cancer of the cervix uteri, screening policies vary widely among European countries, and incidence is increasing in younger women. This study analyzes trends in squamous cell carcinoma (SCC) of the cervix uteri in 13 European countries to evaluate effectiveness of screening against a background of changing risk. Age-period-cohort models were fitted and period and cohort effects were estimated; these were considered as primarily indicative of screening interventions and changing etiology, respectively. A unique set of estimates was derived by fixing age slopes to one of several plausible age curves under the assumption that the relation between age and cervical cancer incidence is biologically determined. There were period-specific declines in cervical SCC in several countries, with the largest decreases seen in northern Europe. A pattern emerged across Europe of escalating risk in successive generations born after 1930. In the western European countries, a decrease followed by a stabilization of risk by cohort was accompanied by period-specific declines. In southern Europe, stable period, but increasing cohort trends, were observed. Substantial changes have occurred in cervical SCC incidence in Europe and well-organized screening programs have been highly effective in reducing the incidence of cervical SCC. Screening and changing sexual mores largely explain the changing period- and cohort-specific patterns, respectively. The increasing risk in recent cohorts is of obvious concern particularly in countries where no screening programs are in place. Further investigation of the effectiveness of opportunistic screening is warranted as is the observation of differing risk patterns in young cohorts in countries with relatively similar societal structures.

Sheep and goats: separating cervix and corpus uteri from imprecisely coded uterine cancer deaths, for studies of geographical and temporal variations in mortality

Analysing time trends in mortality from cancers of the cervix and corpus uteri using routine data sources (such as the World Health Organisation mortality database) involves two major problems: deaths certified as "uterus, unspecified site", and the presence of a combined category comprising unspecified and corpus uteri cancer deaths. To avoid misleading interpretations, the unspecified and the misclassified data must be incorporated into the analysis to produce rates that allow meaningful comparisons between populations and over time. Reallocation methods based on age- and time-specific distributions of cervix and corpus uteri cancer are applied to the unspecified deaths, while for those in the combined category, the age- and time-specific distributions of unspecified and corpus uteri cancer are considered. Adjustments of the general strategies for reallocation were developed to take into account the different quality of the data. Results from eight European countries with different degrees of coding precision are presented. The reallocation methods bring the cervix and corpus uteri mortality trends more in line with the trends for countries with more precise data while keeping the country-specific characteristics. In addition, the methods ensured the availability of time trends for corpus uteri cancer in women age 50 years and older, which were completely missing without reallocation. We propose generally applicable reallocation methods that allow valid time trend analysis of cervix and corpus uteri cancer mortality using datasets of varying precision. Our results show that any sensible analysis of time trends must involve procedures for correcting for unspecified and misclassified uterine cancer deaths. The modified data are available at .

Premalignant lesions of the esophagogastric mucosa

Premalignant esophagogastric (EG) lesions develop against a background of chronic inflammation, called a premalignant condition. For esophageal squamous cell cancer, causal factors include alcohol, tobacco, hot beverages, oral consumption of opioids, and probably infectious agents. For adenocarcinoma in the Barrett's esophagus (BE), gastroesophageal reflux disease (GERD) is the principal causal factor. At the EG junction, adenocarcinoma arises either from the esophagus or from the proximal stomach (cardia). In the distal stomach, chronic gastritis with atrophy is the premalignant condition related to Helicobacter pylori infection. A high intake of salt and low intake of antioxidants also play a role. The histopathology of EG premalignant lesions is now included in the groups low-grade and high-grade intraepithelial neoplasia (IEN) of the revised Vienna classification. Endoscopy is the gold standard for detection of the lesions at the preclinical stage and their appearance is described in subtypes of the type 0 of the Japanese classification, with a distinction between protruding and nonprotruding lesions. There is a priority for primary prevention of causal factors rather than for mass screening, which is justified only in Japan for the prevention of stomach cancer. The trend to early detection of premalignant lesions justifies the development of mini-invasive endoscopic procedures of treatment.

Loss-adjusted survival of cervix cancer in Khon Kaen, Northeast Thailand

For incident cancers of the cervix uteri (601 cases) registered in the population-based cancer registry of Khon Kaen province, Northeast Thailand, in 1985–1990 loss-adjusted survival probabilities were estimated by a logistic regression model with four prognostic factors (age at diagnosis, stage of disease, place of residence and treatment), and compared with observed survival, estimated by the actuarial method. All patients were followed up for a minimum of 5 years, using both passive and active methods. In all, 27.6% of patients were lost to follow-up within 5 years of the index date. The overall observed survival at 5 years was 56.8% and loss-adjusted survival was 54.7%. The difference between the loss-adjusted and observed survival at 5 years was small: 2.1% overall, varying between 0.8 and 3.5 percent units for any prognostic group. The assumption of independence of loss to follow-up and death in the calculation of survival by the actuarial method in this, and probably in other, population-based series, is reasonable and leads to no material bias in the estimates.

Estimation and projection of the national profile of cancer mortality in China: 1991-2005

There are no national-level data on cancer mortality in China since two surveys in 1973–1975 and 1990–1992 (a 10% sample), but ongoing surveillance systems, based on nonrandom selected populations, give an indication as to the trends for major cancers. Based on a log-linear regression model with Poisson errors, the annual rates of change for 10 cancers and all other cancers combined, by age, sex and urban/rural residence were estimated from the data of the surveillance system of the Center for Health Information and Statistics, covering about 10% of the national population. These rates of change were applied to the survey data of 1990–1992 to estimate national mortality in the year 2000, and to make projections for 2005. Mortality rates for all cancers combined, adjusted for age, are predicted to change little between 1991 and 2005 (−0.8% in men and +2.5% in women), but population growth and ageing will result in an increasing number of deaths, from 1.2 to 1.8 million. The largest predicted increases are for the numbers of female breast (+155.4%) and lung cancers (+112.1% in men, +153.5% in women). For these two sites, mortality rates will almost double. Cancer will make an increasing contribution to the burden of diseases in China in the 21st century. The marked increases in risk of cancers of the lung, female breast and large bowel indicate priorities for prevention and control. The increasing trends in young age groups for cancers of the cervix, lung and female breast suggest that their predicted increases may be underestimated, and that more attention should be paid to strategies for their prevention and control.

Estimation and projection of the national profile of cancer mortality in China: 1991-2005

There are no national-level data on cancer mortality in China since two surveys in 1973-1975 and 1990-1992 (a 10% sample), but ongoing surveillance systems, based on nonrandom selected populations, give an indication as to the trends for major cancers. Based on a log-linear regression model with Poisson errors, the annual rates of change for 10 cancers and all other cancers combined, by age, sex and urban/rural residence were estimated from the data of the surveillance system of the Center for Health Information and Statistics, covering about 10% of the national population. These rates of change were applied to the survey data of 1990-1992 to estimate national mortality in the year 2000, and to make projections for 2005. Mortality rates for all cancers combined, adjusted for age, are predicted to change little between 1991 and 2005 (-0.8% in men and +2.5% in women), but population growth and ageing will result in an increasing number of deaths, from 1.2 to 1.8 million. The largest predicted increases are for the numbers of female breast (+155.4%) and lung cancers (+112.1% in men, +153.5% in women). For these two sites, mortality rates will almost double. Cancer will make an increasing contribution to the burden of diseases in China in the 21st century. The marked increases in risk of cancers of the lung, female breast and large bowel indicate priorities for prevention and control. The increasing trends in young age groups for cancers of the cervix, lung and female breast suggest that their predicted increases may be underestimated, and that more attention should be paid to strategies for their prevention and control.

Prevalence of Opisthorchis viverrini infection and incidence of cholangiocarcinoma in Khon Kaen, Northeast Thailand

Liver cancer is the most common cancer in Khon Kaen, Northeast Thailand, because of the high incidence of cholangiocarcinoma (CHCA). Opisthorchis viverrini (OV), a liver fluke, is endemic in the area, and has been evaluated as a cause of CHCA by International Agency for Research on Cancer. Residents of 20 districts in the province were invited to attend a mobile screening programme between 1990 and 2001. Of 24 723 participants, 18 393 aged 35-69 years were tested for OV infection, by examining stools for the presence of eggs. Prevalence of infection in each district was estimated from the sample of the population who had been tested. The incidence of liver cancer in 1990-2001 was obtained for each district from the cancer registry. The average crude prevalence of OV infection in the sample subjects was 24.5%, ranging from 2.1% to 70.8% in different districts. Truncated age-standardized incidence of CHCA at ages >35 years varied threefold between districts, from 93.8 to 317.6 per 100,000 person-years. After adjustment for age group, sex and period of sampling, there was a positive association between prevalence of OV infection and incidence of CHCA at the population level. Associations between CHCA and active OV infection in individuals have become hard to demonstrate, because of effective anti-OV treatment. The relationship may, however, be clear in comparisons between populations, which, for infectious diseases, take into account the contextual effects of group exposure in determining individual outcome. The cancer registry is an appropriate tool for disease monitoring in small areas.

Human papillomaviruses and cancer in Uganda

In a case-control study in Uganda, we examined associations between different cancer sites or types in relation to antibodies against human papillomaviruses (HPV)-16, -18 and -45. For each cancer site or type, the control group comprised all other cancers excluding those known, or thought to be associated with HPV infection (cancers of the uterine cervix, penis and eye). Among controls the seroprevalence of antibodies was 11% (68/616) against HPV-16, 5% (29/605) against HPV-18 and 6% (35/605) against HPV-45. Antibodies against HPV-16 were significantly associated with only two cancers: uterine cervix [prevalence of antibodies 27% (51/191); odds ratio (OR) 2.0, 95% confidence interval (CI) 1.2-3.1, P=0.01] and penis [prevalence of antibodies 27% (4/15); OR 6.4, 95% CI 1.7-24.3, P=0.01]. For both cancers, the risk increased with increasing anti-HPV-16 antibody titre (Ptrend=0.01 for each). No cancer site or type was significantly associated with antibodies against HPV-18 and -45.

The comprehensive cancer monitoring programme in Europe

BACKGROUND

There continue to be major public health challenges arising from the increasing cancer burden in Europe. Drawing upon expertise from other European centres and networks, the Comprehensive Cancer Monitoring Programme in Europe project (CaMon) provides a central information resource of the cancer profile in European populations.

METHODS

The cancer indicators fundamental to disease monitoring in Europe are illustrated in terms of definitions and availability. Where necessary data are supplemented by estimates, in order to make available cancer data to individuals and institutions in all Member and Applicant countries of the European Union (EU). The relevant methodologies are discussed. Finally, a major ongoing project examining time trends of cancer incidence and mortality in 38 European countries is described.

RESULTS

In the European Union, there were approximately 1.6 million new cases of cancer according to the latest year available, and approximately, one million cancer deaths. About 2.6 million new cases of cancer, and 1.6 million deaths were estimated in Europe. Lung cancer is the most common cancer in Europe and together with cancers of the colon and rectum and female breast represent approximately 40% of new cases in Europe.

CONCLUSION

The statistics generated by the project on cancer incidence, mortality, survival and prevalence, together with time trends and projections will be regularly updated and made available to a European Commission, and to a Community-wide audience via the CaMon website and via other means of dissemination, such as peer-reviewed journals.

Cancer incidence and mortality in Portugal

In this paper, we present estimates of national cancer incidence in Portugal in 1996-1998, predictions for the year 2000, and interpret the recent cancer mortality trends in light of observations from epidemiological research and risk factor patterns. In Portugal, national mortality data from vital statistics are available from 1960, while cancer registration has been mandatory since 1988, when three regional cancer registries covering the mainland of the Portuguese Republic were set up. Up until now, however, none of these registries has been able to produce data with an acceptable completeness of registration--hence this study. Mortality data from Portugal for 1996-1998 and incidence data for 1990-1995 from Vila Nova de Gaia (RVNG) (the most complete of the Portuguese cancer registries), 14 Italian registries and nine Spanish registries were assembled to produce the best possible estimates of numbers of incident cases for each age group and gender. A total of 19,880 new cancer cases are estimated to have been diagnosed among men in the year 2000, and nearly 17,000 new cancer cases in women. The most common cancer among Portuguese men in 2000 is cancer of the colorectum (3173 new cases), followed by cancers of the prostate (2973), lung (2611), stomach (2206) and urinary bladder (1360). In women, breast cancer is the most common cancer (4358) followed by cancers of the colorectum (2541), stomach (1494) and corpus uteri (1083). The overall age-standardised cancer mortality rate for men in Portugal increased steeply (1.4% annually) during the period 1988-1998, with prostate cancer (3.6% annually), colon and rectum (3.3%) and lung (2.4%) mostly contributing. Among women, the overall cancer mortality rate was stable (a non-significant decrease of approximately 0.2% per year). These remarkable results, particularly in males, demonstrate the need for a comprehensive national programme against cancer. Since the increasing epidemic of lung cancer (in men), as well as other tobacco-related cancers, is observed in Portugal, the important component of such a programme should be a nationwide tobacco control programme. Improving accessibility to highly effective diagnostic and treatment procedures for cancer in general and colorectal and prostatic cancers in particular should be a priority in the fight against cancer.

Going up or coming down? The changing phases of the lung cancer epidemic from 1967 to 1999 in the 15 European Union countries

Lung cancer, the most common cause of cancer death in the European Union (EU), continues to have an enormous impact on the health experience of the men and women living in the constituent countries. Information on the course of the lung cancer epidemic is essential in order to formulate an effective cancer control policy. This paper examines recent trends in lung cancer mortality rates in men and women in each of the 15 countries, comparing cross-sectional rates of death in younger (aged 30-64 years) and older populations (aged 65 years or over), and the age, period of death, and birth cohort influences in the younger age group. The latter analysis establishes the importance of year of birth, related to modifications in the tobacco habit among recently born generations. The stage of evolution of the lung cancer epidemic varies markedly by sex and country in terms of the direction, magnitude, and phase of development of national trends. In males, there is some consistency in the direction of the trends between EU countries, declines are apparent in most countries, at least in younger men, with rates in older men either reaching a plateau, or also falling. In younger persons, a decreasing risk of lung cancer death reflects changes in successive birth cohorts, due to modifications in the smoking habit from generation to generation, although these developments are in very different phases across countries. Portugal is the exception to the male trends; there are increases in mortality in both age groups, with little sign of a slowing down by birth cohort. In women, there are unambiguous upsurges in rates seen in younger and older women in almost all EU countries in recent decades, and little sign that the epidemic has or will soon reach a peak. The exceptions are the United Kingdom (UK) and Ireland, where lung cancer death rates are now declining in younger women and stabilising in older women, reflecting a declining risk in women born since about 1950. It is too early to say whether the observed plateau or decline in rates in women born very recently in several countries is real or random. To ascertain whether recent trends in lung cancer mortality will continue, trends in cigarette consumption should also be evaluated. Where data are available by country, the proportion of adult male smokers has, by and large, fallen steadily in the last five decades. In women, recent smoking trends are downwards in Belgium, Denmark, Sweden and the Netherlands, although in Austria and Spain, large increases in smoking prevalence amongst adults are emerging. Unambiguous public health messages must be effectively conveyed to the inhabitants of the EU if the lung cancer epidemic is to be controlled. It is imperative that anti-tobacco strategies urgently target women living in the EU, in order to halt their rapidly increasing risk of lung cancer, and prevent unnecessary, premature deaths among future generations of women.

Interim results from a cluster randomized controlled oral cancer screening trial in Kerala, India

A cluster randomized controlled oral cancer screening trial is on-going in the Trivandrum district, India, to evaluate the efficacy of screening in reducing oral cancer mortality. Subjects, aged 35 years and above, in 13 clusters in the Trivandrum district, India, were randomized to the intervention (screening) group (7 clusters, 78969 subjects) to receive three rounds of screening by oral visual inspection by trained health workers at 3-year intervals or to a control group (6 clusters, 74739 subjects). Two rounds of screening were completed between 1995 and 2002 during which 69896 (88.5%) subjects were screened at least once, and 59.7% of the 4408 screen-positive subjects were further investigated. In the intervention group, 344404 person-years were accrued and 329326 person-years were in the control group. In the intervention group, 149 incident oral cancer cases and 65 deaths from oral cancer were observed, and 106 incident cases and 62 deaths from oral cancer were observed in the control group. The programme sensitivity for detection of oral precancerous lesions and cancer was 81.5% and the programme specificity was 84.8%; the programme positive predictive value was 39.6%. In the intervention group 37.6% of the cases were in stages I-II, as opposed to 18.9% in the control group. The 3 year survival rate was 57.5% in the intervention and 38.8% in the control group (P<0.05). The age standardized oral cancer mortality rates were 21.2/100000 person-years in the intervention and 21.3/100000 in the control group. After completing two rounds of screening, oral cancer mortality rates were similar in both study groups.

Infection with Kaposi's sarcoma-associated herpesvirus (KSHV) and human immunodeficiency virus (HIV) in relation to the risk and clinical presentation of Kaposi's sarcoma in Uganda

A case-control study from Uganda found that the risk of Kaposi's sarcoma increased with increasing titre of antibodies against Kaposi's sarcoma-associated herpesvirus (KSHV) latent nuclear antigens, independently of HIV infection. Clinically, widespread Kaposi's sarcoma was more frequent among patients with HIV infection than in those without, but was not related to anti-KSHV antibody titres.

Breast cancer incidence and mortality trends in 16 European countries

Trends in the incidence of and mortality from breast cancer result from a variety of influences including screening programmes, such as those introduced in several European countries in the late 1980s. Incidence and mortality rates for 16 European countries are analysed. Incidence increased in all countries. The estimated annual percent change (EAPC) varied from 0.8 to 2.8% in prescreening years in 6 'screened' countries and from 1.2 to 3.0% in 10 'non-screened' countries. Screening related temporary increases were visible. Earlier mortality trends were maintained in the most recent decade in Estonia (EAPC +1.8%) and Sweden (-1.2%). In other countries, previously increasing trends changed. Trends flattened in Finland, Denmark, France, Italy and Norway (EAPC 0.0 to -0.3%), while they declined in England and Wales (-3.1%), Scotland (-2.0%), and The Netherlands (-1.0%), all of which have national screening programmes, and in Slovakia (-1.1%), Spain (-0.7%), and Switzerland (-1.1%). In some countries with screening programmes, declines in mortality started before screening was introduced, and declines also occurred in non-screened age groups and in some countries without national screening programmes. This suggests that the major determinants of the observed trends vary among the countries and may include earlier detection through screening in countries where this has been introduced, but also improvements in therapy, in countries with or without screening.

Survival of cervix cancer patients in Kampala, Uganda: 1995-1997

The survival experience of 261 patients with cancer of the cervix registered by the Kampala population-based cancer registry, Uganda, in 1995-1997, is described. Vital status of the subjects was established by active methods including a search of hospital records and house visits. Of the 261 cases, 82 (31.4%) were dead and 105 (40.2%) were alive at the closing date of 31 December 1999; the remaining 74 cases (28.4%) were lost during the follow-up period. Overall observed and relative survival at 3 years was 52.4 and 59.9%, respectively. Of these cases, one-quarter (63) had been treated in the radiotherapy department. These cases had better survival (82.6%) than nontreated patients (78.5%) after 1 year of follow-up, but there was no difference at 3 years. HIV status was not significantly related to prognosis. Stage is an important determinant of survival: cases with distant metastasis had a risk of death some three times that of patients with localised disease. Early detection and prompt treatment should improve overall survival from cervix cancer, in the African context.

Reduction of Death Certificate Only (DCO) Registrations by Active Follow Back

Death certificates are an important source of information for cancer registries that help to improve completeness of case finding. In many countries where routine mortality data are considered of poor quality, this source is often regarded as being of little value. We evaluated the contribution of death certificates to the total number of registrations in the years 1993-1997, in the Manila Cancer Registry (MCR). We compared the "standard" practice of retrieving clinical information if the death certificate was completed in a hospital, with active search of additional information from the deceased's relatives when the death was certified at home.The standard procedure allowed us to reduce the proportion of cases registered from a death certificate by 5%. The improvement varied significantly among the most common sites with a reduction of 10% for lymphomas to less than 1% for cancers of the cervix.The proportion of liver cancers registered from a death certificate only (DCO), originally 47%, was reduced to 29% by contacting relatives of the deceased patients. In countries with limited investment in information systems, death certificates, even when recognised as being of poor quality, are an important source of information for cancer registries.

Human papillomavirus infection among women in South and North Vietnam

The incidence rate of invasive cervical carcinoma (ICC) is 4-fold higher in Ho Chi Minh City, in the South of Vietnam, than in Hanoi, in the North. Thus, we explored the prevalence of and the risk factors for human papillomavirus (HPV) infection in these 2 areas. A population-based random sample of married women aged 15-69 years were interviewed and had a gynaecological examination in the urban district of Ho Chi Minh City and in a peri-urban district in Hanoi. HPV DNA detection was performed using a GP5+/6+ primer-mediated PCR enzyme immunoassay. A total of 922 women from Ho Chi Minh and 994 from Hanoi, for whom a Pap smear and HPV-status were available, were evaluated. HPV DNA was detected among 10.9% of women in Ho Chi Minh City and 2.0% in Hanoi (age standardized prevalence, world standard population: 10.6% and 2.3%, respectively). In the 2 areas combined, 30 different HPV types were found, the most common being HPV 16 (in 14 single and 18 multiple infections), followed by HPV 58, 18 and 56. A peak of HPV DNA detection in women younger than age 25 was found in Ho Chi Minh City (22.3%) but not in Hanoi. Major risk factors for HPV DNA detection were indicators of sexual habits, most notably the presence of HSV-2 antibodies, nulliparity and the current use of oral contraceptives. Women in Hanoi showed the lowest HPV prevalence ever reported so far, suggesting that HPV has not spread widely in this population. As expected, HPV prevalence in a population seemed to be closely correlated with ICC incidence rates.

Early detection of cervical cancer with visual inspection methods: a summary of completed and on-going studies in India

India is a high-risk country for cervical cancer which accounts a quarter (126,000 new cases, 71,000 deaths around 2,000) of the world burden. The age-standardized incidence rates range from 16-55 per 100,000 women in different regions with particularly high rates in rural areas. Control of cervical cancer by early detection and treatment is a priority of the National Cancer Control Programme of India. There are no organized cytology screening programmes in the country. The technical and financial constraints to organize cytology screening have encouraged the evaluation of visual inspection approaches as potential alternatives to cervical cytology in India. Four types of visual detection approaches for cervical neoplasia are investigated in India: a) naked eye inspection without acetic acid application, widely known as 'downstaging'; b) naked eye inspection after application of 3-5% acetic acid (VIA); c) VIA using magnification devices (VIAM); d) visual inspection after the application of Lugol's iodine (VILI). Downstaging has been shown to be poorly sensitive and specific to detect cervical neoplasia and is no longer considered as a suitable screening test for cervical cancer. VIA, VIAM and VILI are currently being investigated in multicentre cross-sectional studies (without verification bias), in which cytology and HPV testing are also simultaneously evaluated, and the results of these investigations will be available in 2003. These studies will provide valuable information on the average, comparative test performances in detecting high-grade cervical cancer precursors and cancer. Results from pooled analysis of data from two completed studies indicated an approximate sensitivity of 93.4% and specificity of 85.1% for VIA to detect CIN 2 or worse lesions; the corresponding figures for cytology were 72.1% and 91.6%. The efficacy of VIA in reducing incidence of an mortality from cervical cancer and its cost-effectiveness is currently being investigated in two cluster randomized controlled intervention trials in India. One of these studies is a 4-arm trial addressing the comparative efficacy of VIA, cytology and primary screening with HPV DNA testing. This trial will provide valuable information on comparative detection rates of CIN 2-3 lesions by the middle of 2003. The expected outcomes from the Indian studies will contribute valuable information for guiding the development of public health policies on cervical cancer prevention in countries with different levels of socio-economic and health services development and open up new avenues of research. This paper is available too at: http//www.insp.mx/salud/index.html.

The epidemiology of conjunctival squamous cell carcinoma in Uganda

As part of a larger investigation of cancer in Uganda, we conducted a case-control study of conjunctival squamous cell carcinoma in adults presenting at hospitals in Kampala. Participants were interviewed about social and lifestyle factors and had blood tested for antibodies to HIV, KSHV and HPV-16, -18 and -45. The odds of each factor among 60 people with conjunctival cancer was compared to that among 1214 controls with other cancer sites or types, using odds ratios, estimated with unconditional logistic regression. Conjunctival cancer was associated with HIV infection (OR 10.1, 95% confidence intervals [CI] 5.2-19.4; P<0.001), and was less common in those with a higher personal income (OR=0.4, 95% CI 0.3-0.7; P<0.001)[corrected]. The risk of conjunctival cancer increased with increasing time spent in cultivation and therefore in direct sunlight (chi2 trend=3.9, P=0.05), but decreased with decreasing age at leaving home (chi2 trend=3.9, P=0.05), perhaps reflecting less exposure to sunlight consequent to working in towns, although both results were of borderline statistical significance. To reduce confounding, sexual and reproductive variables were examined among HIV seropositive individuals only. Cases were more likely than controls to report that they had given or received gifts for sex (OR 3.5, 95% CI 1.2-10.4; P=0.03), but this may have been a chance finding as no other sexual or reproductive variable was associated with conjunctival cancer, including the number of self-reported lifetime sexual partners (P=0.4). The seroprevalence of antibodies against HPV-18 and -45 was too low to make reliable conclusions. The presence of anti-HPV-16 antibodies was not significantly associated with squamous cell carcinoma of the conjunctiva (OR 1.5, 95% CI 0.5-4.3; P=0.5) and nor were anti-KSHV antibodies (OR 0.9, 95% CI 0.4-2.1; P=0.8). The 10-fold increased risk of conjunctival cancer in HIV infected individuals is similar to results from other studies. The role of other oncogenic viral infections is unclear.

Estimates of cancer incidence and mortality in Europe in 1995

Cancer incidence and mortality estimates for 1995 are presented for the 38 countries in the four United Nations-defined areas of Europe, using World Health Organization mortality data and published estimates of incidence from national cancer registries. Additional estimation was required where national incidence data was not available, and the method involved incorporating the high quality incidence and mortality data available from the expanding number of population-based cancer registries in Europe. There were an estimated 2.6 million new cases of cancer in Europe in 1995, representing over one-quarter of the world burden of cancer. The corresponding number of deaths from cancer was approximately 1.6 million. After adjusting for differing population age structures, overall incidence rates in men were highest in the Western European countries (420.9 per 100,000), with only Austria having a rate under 400. Eastern European men had the second highest rates of cancer (414.2), with extremely high rates being observed in Hungary (566.6) and in the Czech Republic (480.5). The lowest male all-cancer rate by area was observed in the Northern European countries, with fairly low rates seen in Sweden (356.6) and the UK (377.8). In contrast to men, the highest rates in women were observed in Northern Europe (315.9) and were particularly high in Denmark (396.2) and the other Nordic countries excepting Finland. The rates of cancer in Eastern European women were lower than in the other three areas, although as with men, female rates were very high in Hungary (357.2) and in the Czech Republic (333.6). There was greater disparity in the mortality rates within Europe--generally, rates were highest in Eastern European countries, notably in Hungary, reflecting a combination of poorer cancer survival rates and a higher incidence of the more lethal neoplasms, notably cancer of the lung. Lung cancer, with an estimated 377,000 cases, was the most common cancer in Europe in 1995. Rates were particularly high in much of Eastern Europe reflecting current and past tobacco smoking habits of many of its inhabitants. Together with cancers of colon and rectum (334,000), and female breast (321,000), the three cancers represented approximately 40% of new cases in Europe. In men, the most common primary sites were lung (22% of all cancer cases), colon and rectum (12%) and prostate (11%), and in females, breast (26%), colon and rectum (14%) and stomach (7%). The number of deaths is determined by survival, as well as incidence; by far the most common cause of death was lung cancer (330,000)--about one-fifth of the total number of cancer deaths in Europe in 1995. Deaths from cancers of the colon and rectum (189,000) ranked second, followed by deaths from stomach cancer (152,000), which due to poorer survival ranked higher than breast cancer (124,000). Lung cancer was the most common cause of death from cancer in men (29%). Breast cancer was the leading cause of death in females (17%). Cancer registries are a unique source of information on cancer incidence and survival, and are used here with national mortality to demonstrate the very substantial burden of cancer in Europe, and the scope for prevention. Despite some provisos about data quality, the general patterns which emerge in Europe verify the role of past exposures and interventions, and more importantly, firmly establish the need for cancer control measures which target specific populations. In particular, there is a clear urgency to combat the ongoing tobacco epidemic, now prevalent in much of Europe, particularly in the Eastern countries.

Global cancer statistics in the year 2000

Estimation of the burden of cancer in terms of incidence, mortality, and prevalence is a first step to appreciating appropriate control measures in a global context. The latest results of such an exercise, based on the most recent available international data, show that there were 10 million new cases, 6 million deaths, and 22 million people living with cancer in 2000. The most common cancers in terms of new cases were lung (1.2 million), breast (1.05 million), colorectal (945,000), stomach (876,000), and liver (564,000). The profile varies greatly in different populations, and the evidence suggests that this variation is mainly a consequence of different lifestyle and environmental factors, which should be amenable to preventive interventions. World population growth and ageing imply a progressive increase in the cancer burden--15 million new cases and 10 million new deaths are expected in 2020, even if current rates remain unchanged.

Population-based survival from colorectal cancer in Mumbai, (Bombay) India

Survival estimates of patients registered by population-based cancer registries reflect the average prognosis from a given cancer as they are based on unselected patients with a wide range of natural histories and treatment patterns. In this paper, we report the survival experience of colorectal cancer patients in Mumbai (Bombay), India. Follow-up information on 1642 colorectal cancer patients registered by the Bombay Population-based Cancer Registry for the period 1987-1991 was obtained by matching with death certificates from the Bombay vital statistics registration system, postal/telephone enquiries, home visits and scrutiny of medical records. Cumulative observed and relative survival proportions were calculated by Hakulinen's method. For comparison of results with other populations, age-standardised relative survival (ASRS) was calculated by directly standardising age-specific relative survival to the specific age distributions of the world standard cancer patient population in 1985. The log-rank test was used to identify the potential prognostic variables which were introduced step-wise into a Cox regression model to identify the independent predictors of survival. The 5-year relative survival was 36.6% for colon and 42.2% for rectal cancer. Age, site of cancer and clinical stage of disease emerged as independent predictors of survival. Age-specific 5-year relative survival declined with advancing age. Survival at 5 years was 61.2% for localised colon cancer; 31.9% for regional and 9.0% for distant metastatic disease. These were 65.7, 25.6 and 4.3%, respectively for rectal cancers. Comparison of the results with other populations revealed significant variations, which seem to be related to differences in detection and treatment. The prognosis from colorectal cancer in Mumbai and developing countries, may be further improved through early detection linked with treatment.

Cancer incidence in Blantyre, Malawi 1994-1998

In this paper, we report the first results from the population-based cancer registry for Blantyre district, Malawi, for the period 1994-1998. In this 5-year period, 1245 cases were recorded in males (an estimated age-standardized incidence of 92.0 per 100,000) and 1003 in females (an age standardised rate (ASR) of 88.8 per 105). The overall percentage of cases with histological verification was just 41.8%, indicating that case-finding outside the laboratory had been quite successful; nevertheless the rather low rates suggest possible underdiagnosis of cancer, as well as cases missed. As in other reports from the region, the contemporary pattern is dominated by Kaposi's sarcoma (KS) (55.2% cancers in men, 28% in women), the effect of the evolving epidemic of AIDS. The incidence of cervix cancer in women is high (ASR 26.2 per 105), and there are moderately high rates of oesophageal cancer (ASR 15.4 per 105 in men, 9.3 per 105 in women). In childhood, the cancer profile is dominated by Burkitt's lymphoma, which accounts for 42.4% of cancers; KS is now the second most frequent cancer of childhood.

Cancer in the Gambia: 1988-97

We describe the incidence of cancer in The Gambia over a 10-year period using data collected through the Gambian National Cancer Registry. Major problems involved with cancer registration in a developing country, specifically in Africa are discussed. The data accumulated show a low overall rate of cancer incidence compared to more developed parts of the world. The overall age standardized incidence rates (ASR) were 61.0 and 55.7 per 100 000 for males and females, respectively. In males, liver cancer was most frequent, comprising 58% of cases (ASR 35.7) followed by non-Hodgkin lymphoma, 5.4% (ASR 2.4), lung 4.0%, (ASR 2.8) and prostate 3.3% (ASR 2.5) cancers. The most frequent cancers in females were cervix uteri 34.0% (ASR 18.9), liver 19.4% (ASR 11.2), breast 9.2% (ASR 5.5) and ovary 3.2% (ASR 1.6). The data indicate that cancers of the liver and cervix are the most prevalent cancers, and are likely to be due to infectious agents. It is hoped that immunization of children under 1 year against hepatitis B will drastically reduce the incidence of liver cancer in The Gambia.

Completeness in an African cancer registry

OBJECTIVE

A high level of completeness of case-finding is essential if data from cancer registries are to be useful for comparative studies. A large case series, collected independently of the cancer registry case-finding mechanisms, as part of a study of the influence of HIV infection on cancer risk, was used to evaluate the completeness of the registry in Kampala, Uganda, for the years 1994-1996.

RESULTS

For adults aged 15 or more, the completeness of registration of diagnosed cancer cases was 89.6% (95% CI 87.0-91.7) overall. It varied with age (better ascertainment of younger cases, aged under 30) and cancer site (with Kaposi sarcoma cases significantly better identified), and cases with a histology report were more likely to be registered than those without (though the difference was not significant). Completeness declined with time, as in most registries, which continue to identify "late" cases some time after the initial diagnosis.

CONCLUSION

This is the first objective measurement of completeness of cancer registration in Africa, and it gives reassurance that published incidence rates are reasonablyaccurate (provided that there is not an insistence on the very latest results).

Lung cancer screening: improved survival but no reduction in deaths--the role of "overdiagnosis"

BACKGROUND

Randomized controlled trials (RCTs) of lung cancer screening consistently show an excess number of cancer cases and longer survival in screened groups, but no difference in mortality between screened and control populations.

METHODS

The current study reviewed the various types of biases that confuse comparisons based on intermediate endpoints such as stage distribution and survival and the reasons for basing evaluations in RCTs of screening for early cancers on mortality from a specific cancer.

RESULTS

Four RCTs all showed improved stage of disease and survival in screened subjects, but there was no difference in mortality between screened and unscreened populations. The possible explanations for the higher incidence are chance (failed randomization) or "overdiagnosis" (detection of cases by screening that otherwise would never have surfaced). Analysis of the trial results confirmed that chance alone was a very unlikely explanation. Evidence suggests that some overdiagnosis of lung cancer is likely in screened subjects. This is a consistent observation in all other programs of screening for early cancers (breast, prostate, and neuroblastoma).

CONCLUSIONS

Overdiagnosis of cancer cases resulting from the screening process itself will give rise to excess cases of disease, and may, at least in part, explain the observations in the randomized trials.

Incidence in Izmir in 1993-1994: first results from Izmir Cancer Registry

A population-based cancer registry, covering the province of Izmir (population 2.7 million, 1993-1994) in Western Turkey was established in 1992. Results for 1993-1994 are presented. Overall cancer incidence was higher in males than in females (age-standardised rates 157.5 and 94.0 per 100000, respectively), as in previous non-population-based series. The principal cancers in males were tobacco-related - lung (age-standardised incidence rate (ASR) 61.6), bladder (ASR 11.0) and larynx (ASR 10.6), consistent with the high prevalence of smoking, and use of traditional high-tar tobaccos. Skin cancers were also relatively common (ASR 11.5 for cancers excluding melanoma). Gastrointestinal cancers were relatively rare. In women, breast cancer was by far the most common malignancy (ASR 24.4); cervical cancer was relatively rare (ASR 5.4). There is probably an underestimate of incidence, due to an inability to use data from certain sources (e.g. death certificates), resulting in a rather high proportion of histologically verified cases (93.7% overall). Nevertheless, the overall profile is an accurate reflection of incidence in this region of Turkey and provides much of the information required for planning strategies to control cancer.

Non-Hodgkin lymphoma in Uganda: a case-control study

BACKGROUND

Lymphomas are a relatively common complication of AIDS in western countries, but little is known of the impact of the AIDS epidemic in Africa on the risk of these tumours.

OBJECTIVE

To investigate the types of non-Hodgkin lymphoma (NHL) occurring in Kampala, Uganda, their association with Epstein-Barr virus (EBV), and how their risk is modified by HIV and other variables.

METHODS

A case-control study comparing NHL cases with age/sex-matched controls. Lymphoma cases included 50 histologically diagnosed adults (31 with validation and phenotyping) and 132 histologically diagnosed children (61 with validation and phenotyping). Controls were adults with cancers unrelated to HIV and children with non-infectious diseases.

RESULTS

Most (90%) childhood lymphomas were EBV-positive Burkitt's lymphoma (BL), with no association with HIV. Adult lymphoma cases were mainly BL (mostly EBV positive) or diffuse B cell lymphomas (71%). Only a weak association was found with HIV infection; a more precise estimate was obtained with the total series (OR 2.2, 95% CI 0.9-5.1) than validated/phenotyped cases (OR 2.1, 95% CI 0.3-6.7). Higher socioeconomic status adults, who travelled away from home, or had a history of sexually transmitted diseases, appeared to have a moderately increased risk of lymphoma.

CONCLUSION

Childhood lymphomas were predominantly endemic BL, the risk of which was not modified by HIV. In adults, the risk associated with HIV was much lower in Uganda than in western countries, possibly because of the poor survival of immunosuppressed HIV-positive individuals. Future studies will require careful attention to subtyping of lymphomas, to investigate the possible differences between them.

Lung cancer screening: improved survival but no reduction in deaths--the role of "overdiagnosis"

BACKGROUND

Randomized controlled trials (RCTs) of lung cancer screening consistently show an excess number of cancer cases and longer survival in screened groups, but no difference in mortality between screened and control populations.

METHODS

The current study reviewed the various types of biases that confuse comparisons based on intermediate endpoints such as stage distribution and survival and the reasons for basing evaluations in RCTs of screening for early cancers on mortality from a specific cancer.

RESULTS

Four RCTs all showed improved stage of disease and survival in screened subjects, but there was no difference in mortality between screened and unscreened populations. The possible explanations for the higher incidence are chance (failed randomization) or "overdiagnosis" (detection of cases by screening that otherwise would never have surfaced). Analysis of the trial results confirmed that chance alone was a very unlikely explanation. Evidence suggests that some overdiagnosis of lung cancer is likely in screened subjects. This is a consistent observation in all other programs of screening for early cancers (breast, prostate, and neuroblastoma).

CONCLUSIONS

Overdiagnosis of cancer cases resulting from the screening process itself will give rise to excess cases of disease, and may, at least in part, explain the observations in the randomized trials.

Czech Study on Lung Cancer Screening: post-trial follow-up of lung cancer deaths up to year 15 since enrollment

BACKGROUND

The study was launched in the mid-1970s to explore the capability of screening by chest X-ray and sputum cytology to be used as an effective component of the lung cancer control program in the Czech Republic, a Central European country with a high and increasing occurrence of lung cancer in men at that time. A complementary objective of this report is to ascertain whether the cumulative numbers of lung cancer deaths would equalize in the two randomized groups during a prolonged follow-up period.

METHODS

Six thousand three hundred sixty-four males who were heavy cigarette smokers, aged 40-64 years, were enrolled during a general health survey in 6 districts of the Czech Republic. At initial X-ray and sputum examination, 19 prevalent lung carcinoma cases were diagnosed. After stratified randomization, the remaining subjects entered a 3-year study: the intervention group (3171 participants) was subjected to semiannual chest X-rays and sputum investigation whereas the controls (3174 participants) had 1 examination only by chest X-rays and sputum investigation, 3 years after entry. During a further 3-year follow-up, a chest X-ray was taken at the end of Years 4, 5, and 6 for both the intervention and control groups. Subjects in both groups who were suspected to have lung carcinoma or other disease on the basis of screening results or symptoms were subjected to appropriate diagnostic studies and treatment. Data on all causes of death in Years 1-6 and on deaths from the lung cancer in Years 7-15 of participants in the intervention and control groups were compared.

RESULTS

The incidence rate of lung carcinoma from the intervention group was significantly higher than from the controls in the initial 3-year study period (P < 0.05), but not for the initial 6-year period (P = 0.06). Lung carcinoma cases detected by screening were identified at an earlier stage, were more often resectable, and had a significantly better survival than interval cases diagnosed mainly because of symptoms. There was no significant difference in the lung cancer mortality rate between the 2 groups in the initial 3-year study period or during follow-up prolonged up to Year 15 since enrollment.

CONCLUSIONS

The study gave no evidence that screening for lung cancer by chest X-ray is beneficial in terms of reducing mortality. Based on the results of this study, there is no justification to recommend semiannual screening as a component of a comprehensive lung cancer control program.

Alcohol drinking, body mass index and the risk of oral leukoplakia in an Indian population

Although tobacco habits have been associated with the risk of oral leukoplakia, alcohol drinking and body mass index (BMI) as risk factors have not been well established. The purpose of this study is to evaluate the independent effects of drinking, BMI, tobacco chewing and smoking on the risk of oral leukoplakia. A case-control study was conducted, with data from an ongoing randomized oral cancer screening trial in Kerala, India. Trained health workers conducted interviews and performed oral visual inspections to identify oral premalignant lesions such as leukoplakia. The logistic regression model in SAS was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). A total of 927 leukoplakia cases and 47,773 controls were included in the analysis. Ever alcohol drinking was a significant risk factor for oral leukoplakia among nonsmokers (OR=2.1, 95%CI=1.3, 3.4) and non-chewers (OR=1.8, 95%CI=1. 3, 2.5) after adjusting for age, sex, education, BMI and tobacco habits. The association with alcohol drinking was stronger among women (OR=3.9, 95%CI=1.5, 10.4) than men (OR=1.5, 95%CI=1.3, 1.9). An inverse dose-response relationship was observed between BMI and the risk of oral leukoplakia (p for trend=0.0075). Tobacco chewing was a stronger risk factor for women (OR=37.7, 95%CI=24.2, 58.7) than for men (OR=3.4, 95%CI=2.8, 4.1). Smoking was a slightly stronger risk factor for men (OR=3.3, 95%CI=2.5, 4.3) than for women (OR=2.0, 95%CI=1.5, 2.9). In conclusion, alcohol drinking was found to be an independent risk factor while BMI might be inversely associated with the risk of oral leukoplakia in an Indian population.

Cancer incidence in Abidjan, Ivory Coast: first results from the cancer registry, 1995-1997

BACKGROUND

There are few data concerning cancer incidence rates in contemporary West Africa. The first data from the cancer registry of Abidjan, the capital of Ivory Coast, for the period 1995-1997 are reported in the current study.

METHODS

The cancer registry attempts to record data on all new cases of cancer diagnosed in the city of Abidjan, including cases without histologic confirmation of diagnosis.

RESULTS

Two thousand eight hundred fifteen new cancer cases were registered in 3 years, corresponding to age-standardized (world population) incidence rates of 83.7 per 100,000 in men and 98. 6 per 100,000 in women. As reported elsewhere in West Africa, the principal cancers in men were liver cancer (15%) and prostate cancer (15.8%), with modest rates of non-Hodgkin lymphoma (10.5%) and gastric cancer (4.5%). In women, breast cancer was the most frequent tumor (25.7%), followed by cervical cancer (24.0%) and non-Hodgkin lymphoma (7.3%). In contrast to other registry data from West Africa, Kaposi sarcoma occurs with moderate frequency (7.7% of cases reported in men and 2.1% in women). In the pediatric age group, relatively high incidence rates were found for Burkitt lymphoma.

CONCLUSIONS

Although there most likely is some underascertainment of cases, so that the actual incidence rates may be underestimated, the cancer profile should be a fair reflection of the true situation. In addition to tumors that are well known to be common in sub-Saharan Africa, such as cancers of the liver and cervix, this urban population shows some features of "Westernization" of cancer patterns, in particular the relatively high rates of breast cancer and prostate cancer. The effects of the acquired immunodeficiency syndrome epidemic are reflected in the moderate rates of Kaposi sarcoma reported.

Survival from head and neck cancer in Mumbai (Bombay), India

BACKGROUND

Head and neck cancers, among the 10 most frequent cancers in the world, are common in regions with a high prevalence of tobacco and alcohol habits. They account for one-fourth of male and one-tenth of female cancers in India. The authors report and discuss the survival from these cancers in Mumbai (Bombay), India.

METHODS

Follow-up information on 6311 head and neck cancer patients registered in the Bombay Population-Based Cancer Registry for the period 1987-1991 was obtained by a variety of methods, including matching with death certificates from the Bombay vital statistics registration system, postal/telephone enquiries, home visits, and scrutiny of medical records. The survival for each case was determined as the duration between the date of incidence and the date of death or date of loss to follow-up or the closing date of the study (December 31, 1996). Cumulative observed and relative survival were calculated by the Hakulinen method. For comparison of results with other populations, age-standardized relative survival (ASRS) was calculated by directly standardizing age specific relative survival to the specific age distributions of the estimated global incidence of major cancers in 1985. The log rank test was used in univariate analysis to identify the potentially important prognostic variables. The variables showing statistical significance in univariate analysis were introduced stepwise into a Cox regression model to identify the independent predictors of survival.

RESULTS

The 5-year relative survival rates were 74.5% for the lip, 42.7% for the anterior tongue, 25.5% for the posterior tongue, 45.1% for the mouth, 29.7% for the oropharynx, 38.7% for the nasopharynx, 29.1% for the hypopharynx, and 41.2% for the larynx. Age, marital status, religion, and site and clinical extent of disease emerged as independent predictors of survival. Age specific 5-year relative survival declined with advancing age. Single patients had a 20% excess risk of death compared with married patients. Those with cancers of the lip, mouth, nasopharynx, and larynx had a better prognosis than those with cancer at other sites. Those with regional spread of disease experienced a threefold increased risk of death, and those with distant metastasis experienced a sixfold excess risk. Less than one-fourth of cancers were localized in the organ of origin at diagnosis; 5-year survival for localized cancers ranged from 52.9% to 80.2% depending on the subsite.

CONCLUSIONS

There were significant variations in survival from cancer at individual sites within the head and neck region. Comparison with other populations revealed variations that seemed to be related to differences in detection and treatment. Tobacco and alcohol control measures and early detection linked with treatment are important measures to reduce mortality from head and neck cancer.

Incidence of childhood cancer in Ho Chi Minh City, Vietnam, 1995-97

Incidence rates of childhood cancer for the city of Ho Chi Minh are presented for the first time. For the 3-year period 1995-97, a total of 302 cancer cases were registered in children under 15 years of age, with a male to female ratio of 1.1. The overall crude rate was 78.8 and the age-standardised incidence rate was 88.4 per million person-years, which was low in comparison with other countries in eastern Asia and with the predominantly white population of Australia. Leukaemia (principally acute lymphocytic), brain tumours and lymphomas were the most common childhood neoplasms, which is consistent with the pattern observed in other registries of the region. The rate of retinoblastoma was higher than in the other regional registries. On the other hand, no cases of hepatocellular carcinoma were registered.

Chewing tobacco, alcohol, and the risk of erythroplakia

Although chewing tobacco, smoking, and alcohol drinking have been suggested as risk factors for oral cancer, no study has examined the relationship between those factors and the risk of erythroplakia, an uncommon but severe oral premalignant lesion. In this study, we have analyzed the effects of chewing tobacco, smoking, alcohol drinking, body mass index, and vegetable, fruit, and vitamin/iron intake on the risk of erythroplakia and explored potential interactions between those factors in an Indian population. A case-control study including 100 erythroplakia cases and 47,773 controls was conducted, as part of an on-going randomized oral cancer screening trial in Kerala, India. The analysis was based on the data from the baseline screening for the intervention group, where the diagnostic information was available. The information on epidemiological risk factors was collected with interviews conducted by trained health workers. The erythroplakia cases were identified by health workers with oral visual inspections, and then confirmed by dentists and oncologists who made the final diagnosis. The odds ratios (OR) and their 95% confidence intervals (CIs) were calculated by the logistic regression model using SAS software. The adjusted OR for erythroplakia was 19.8 (95% CI, 9.8-40.0) for individuals who had ever chewed tobacco, after controlling for age, sex, education, body mass index, smoking, and drinking. The adjusted OR for ever-alcohol-drinkers was 3.0 (95% CI, 1.6-5.7) after controlling for age, sex, education, body mass index, chewing tobacco, and smoking. For ever-smokers, the adjusted OR was 1.6 (95% CI, 0.9-2.9). A more than additive interaction on the risk of erythroplakia was suggested between tobacco chewing and low vegetable intake, whereas a more than multiplicative interaction was indicated between alcohol drinking and low vegetable intake, and between drinking and low fruit intake. We concluded that tobacco chewing and alcohol drinking are strong risk factors for erythroplakia in the Indian population. Because the CIs of interaction terms were wide and overlapping with those of the main effects, only potential interactions are suggested.