Radiol Oncol 1994; 28: 290-7. Epidemiological features of lung cancer in Slovenia Vera Pompe-Kirn, Maja Primic Zakelj, Neva Volk Institute of Oncology, Zaloska 2, Ljubljana, Slovenia Lung cancer is the most frequent cancer in the world with wide geographical variations in risk. In Europe its incidence trends in men are decreasing in the most affected countries such as Scotland and Finland, increasing moderately in Eastern Europe, and increasing steeply in Southern Europe. The incidence trends in women are increasing everywhere. Many risk factors have been identified, and the overwhelming role of tobacco smoking has been repeatedly demonstrated. According to the data of the Cancer Registry of Slovenia in the time period 1961-1990, the incidence of lung cancer in Slovenia was increasing. In the 80's the increase was moderate in men and steep in women. The cumulative rates in men were in the middle of those established for selected European states and regions while the rates in women were at the bottom. The results of the birth cohort analysis indicated a stabilisation of the rates in men and further increase of the rates in women. About 25 % of cases in both sexes were diagnosed in a localised stage. In men the percentage of the localised stage was increasing by age which was explained by a decreasing percentage of the more aggressive small cell carcinoma. More squamous cell carcinomas were registered in men, and more adenocarcinomas in women. The observed survival of lung cancer patients was around 7 % for men and 6 % far women, and has not changed since 1970. In 1989, 42 % of adult men and 24 % of adult women in Slovenia were smokers. In the period 1975-1994, the percentage of smokers was decreasing in men, and increasing in women. These results are a challenge for more efficient antismoking campaigns, especially among women. Key words: Jung neopJasm-epidemioJogy; SJovenia Introduction Lung cancer is now the most frequent cancer in the worJd. Pisani, Parkin and Ferlay estimated that in the year 1985 the worJd burden had been: 896000 new Jung cancer cases (677000 in men and 219 000 in women) and 785 000 Correspondence to: Professor Vera Pompe-Kirn, MD, PhD, Institute of Oncology, Zaloska 2, 61105 Ljubljana, Slovenia. Phone: + 3866113 24113. UDC: 611.24-006.6-036.2 deaths due to lung cancer (600000 in men, and 185000 in women).1 There are wide geographicaJ variations in the risk. In Europe alone the crude incidence rates are varying from 180-45/100000 in men, and from 55-5/100000 in women.2 In men the timetrends in incidence are different. They are decreasing in most affected countries such as Scotland, EngJand and FinJand, increasing mo-derateJy in Eastern Europe, and increasing steepJy in Southern Europe. In women the trends are increasing everywhere.3 Epidemiological features of lung cancer in Slovenia 291 Study of the epidemiology of lung cancer has been one of the most rewarding aspects of medical research in the past 40 years. It has been shown how a disease that has become the most common type of cancer throughout the world can be made to become relatively rare.4 Many risk factors have been identified: tobacco smoking, atmospheric pollution, occupational hazards, ionising radiation, some familial, genetic and other host factors as well as the protective role of diet rich in fruit and vegetable. The overwhelming role of tobacco smoking in the causation of lung cancer has been repeatedly demonstrated.4' 5 The aim of our study was to analyse lung cancer incidence in Slovenia in depth and to compare the obtained results with the available data on Slovenian smoking habits. Material and methods Lung cancer incidence and survival data were drawn from the data base of the Cancer Registry of Slovenia. This Registry was established in 1950 at the Institute of Oncology as a population-based cancer registry. Data from the period 1961-1990 were analysed. Data on smoking habits have been gathered regularly within the framework of" Slovenian public opinion survey on a random sample of 2093 adult men and women since 1975.6 These data were kindly supplied by the Faculty of Social Sciences. Standard methods in descriptive epidemiology were used.7 Crude incidence rate has been defined as the rate of total annual number of new cases per 100 000 popuJation in the relevant year. Comulative incidence rate is a speciaJ age-standardised rate. It is the sum over each year of age of the age-specific incidence rates taken from birth to age 74. It can be interpreted either as a directly age standardised rate with the same popuJation size in each age-group, or as an approximation to the cumulative risk. Staging was based on the international cancer registries regulation. According to this reguJa-tion, ali investigation methods including surgery are considered in stage determination of soJid tumours. In the case that patient was not treated previously, the autopsy report is considered as weJI. The lung cancer cases were coded as JocaJised when tumour was confined to the same site of the Jung and no nodes or distant metastasis were present. Results Lung cancer incidence and survival In SJovenia the incidence of Jung cancer was increasing in both sexes (Figure 1). In men the increase was steep in the sixties and seventies, and moderate in the eighties, whiJe in women the increase was steeper in the eighties than before. Year Figure 1. Crudc annual Jung canccr incidcncc ratcs by scx, Slovcnia 1961-90. 292 Pompe-Kirn V et al. 20 100 fbC) fb'l, ^ fb'o fbb "^"qj "qj N \ ( men women nil i Mill i mil iii i i i i i i i i o>» fb fb c^ c^0 "J V'l, d^ fb" fbfb Year Figure 2. Percentage of clclerly population by sex. Slovenia 1971-90. Year Figure 3. Cumulative annual lung cancer incidence rates by sex, Slovenia 1961-90. f \ i In this long time period the population tree of Slovenia changed.8 The percentage of the elderly population was growing till 1982 to be temporarily stabilised in the eighties (Figure 2). We have to take this changing age distribution into account and look at the age standardized cumulative rates, at the risk of getting lung cancer till the age of 75 years (Figure 3). In men a steeper increase in the risk to get lung cancer in the sixties and at the beginning of seventies, and in women a steady increase in the eighties was confirmed. These cumulative rates in men place Slovenia in the middle of the rank order of selected European states and regions (Figure 4). In Slovenia the risk of getting lung cancer in a man till the age of 75 years was almost 8/100, in comparison to the Netherlands and Lower Silesia in Poland where it was about 11/100, and with Norway and Sweden where the rates were the lowest 3-4/100. With the cumulative rates in women (0.9/100), Slovenia was placed at the bottom, very close to different regions of Germany (Figure 5). In Slovenia itself, the cumulative rates varied. In men high rates were found in industrial and mining settlements, while in women they were found in the capital region of Slovenia. 9 In the commune of Idrija stable high rates were found in both sexes. To predict properly further trends of lung cancer in Slovenia a detailed analysis on trends in the incidence of specific age-groups by time periods (Figure 6a, b) and by birth cohorts was needed (Figure 7a, b). In men the peak of the rates plotted by time periods shifted to the left and a stabilisation in the eighties was observed. Epidemiological features of lung cancer in Slovenia 293 NL, Eindhoven PL, Lower Silesia UK, Scotland CZ, Boh.& Moravia Italy, Trieste Slovakia D, Saarland Finland H, Szabolcs UK, South Thames D, former GDR CH, Geneva Slovenia Denmark Belarus S, Tarragona Norway Sweden 0 10 20 30 Figure 4. Cumulative average annual lung cancer incidcncc rates in men, Europe 1983-87. _ zi::zizi::ziiij 40 In women the peak remained in the oldest age groups and the curve was higher in each subsequent time period. We tried to explain such a different behaviour by sex with a birth cohort analysis. In the birth cohort analysis (Figure 7) we presented the same data in a different way. The rates were plotted by birth cohorts, by the year of birth of newly diagnosed lung cancer patients. There was a clear cohort effect in both sexes. An encouraging one in men with lower rates in younger generations, bom around 1931 and later, and a warning one in women, with higher rates in younger generations in all age groups. In the period 1981-90 in Slovenia about 25 % of patients of both sexes were diagnosed in the localised stage (Figures 8 and 9). The stage distribution differed by age however. In men only, a growing percentage of the localised stage in the elderly was obvious. To explain this observation, we analysed the histologic types of lung cancer in Slovenia by age in men and women (Figure 10a, b). The distribution differed by sex. More adenocarcinomas were registered in women, and more squamous cell carcinomas in men, while approximately the same percentage of carcinomas were nonspeci-fied or microscopically non verified. The percentage of small cell carcinoma decreased by age in both sexes. Population survival of lung cancer patients in Slovenia did not change in the period 19701989. The observed five year survival rate of patients aged 0-74 years was around 7 % for men and around 6 % for women. Smoking habits In 1989, 42 % of adult men and 24 % of adult women in Slovenia were smokers. With these data Slovenia was placed in the middle of the EC countries. In men the highest percentage 294 Pompe-Kirn V et al. UK, Scotland Denmark UK, South Thames CH, Geneva 1, Trieste PL, Lower Silesia Norway Sweden CZ, Boh.& Morav. H, SzaboI cs Slovakia Finland NL, Eindhoven D, Saarland D, former GDR Slo venia Belarus S, Tarragona 0 10 20 30 40 Figure 5. Cumulative average annual lung cancer incidence rates in womcn, Europe 1983-87. of smokers was seen in the age group 31-40 years while in women it was in the age group 26-30 years. The percentage of ex-smokers was higher in men in all age groups after the age of 25. Smoking habits differed by education. The highest percentages were seen in men with elementary and professional education, and they were highest in women with professional and middle education. In the time-period 19751994, the percentage of smokers ainong men was decreasing whereas among women it was increasing (Figure 11). The decrease in men was observed in all age groups after the age of 26, while the increase in women was observed till the age of 61. Smoking habits differed by communes of Slovenia. In 1989, more smokers were found in industrial and mining settlements.9 Unfortunately, an analysis by sex was not performed. Discussion and conclusion In the time period 1961-1990 the incidence of lung cancer in Slovenia was increasing. In the eighties the increase was moderate in men and steep in women. The cumulative rates in men were in the middle of those established for selected European states and regions, while the rates in women were at the bottom. The results of the birth cohort analysis indicate a stabilisation of the rates in men and further increase of the rates in women in the near future. About 25 % of cases in both sexes were diagnosed in the localised stage. In men, the stage distribution differed by age, however. The localised stage was increasing with age. With age also the percentage of more aggressive small cell carcinoma was decreasing. A similar observation was reported by Teeter and cowor-kers in 1990.10 Epidemiological features of lung cancer in Slovenia 295 1,000 1,000 100 O o q o o <0 a: Age Figure 6a. Age-specific Jung cancer incidence rates in men by time periods, Slovenia 1961-90. Age Figure 6b. Age-specific lung canccr incidence rates in women by time periods, Slovenia 1961-90. More squamous cell carcinomas were registered in men, and more adenocarcinomas in women. Such results were expected according to other reports in the literature.11 The observed survival of lung cancer patients was around 7 % for men and 6 % for women, and has not changed since 1970. This statement is a challenge not only for clinicians in their search for additional pieces to the unresolved puzzle of a more efficient treatment, but first of all for health educators and general practitioners in their attempt to develop more efficient antismoking campaigns, especially among women. According to the described smoking habits in 1989 in Slovenia, (42 % of adult men and 24 % of adult women were smokers), and the fact that by eliminating tobacco smoking, the worldwide potential to reduce the incidence of lung cancer would reach 80-90 % for men and 60-80% for women,i2 a lot of work still waits to be done in the future. 296 Pompe-Kirn V et al. 1,000 100 o o o o o 10 75-79 70-74 65-69 60-64' 55-59 40;44 100 00 ir (V (V oí» ^ oí o5 ,05 ,05 ,05 ,05 ,05 ,05 ,05 ,05 ,05 ,05 ,05 Year of birth Figure 7b. Agc-spccific lung canccr incidence rates in women by birth cohots, Slovenia 1961-90. 35-44 ÍSÉ11 fag»_________ 45-49 fUST^ 60-64 65-69 70-74 75-79 »ifipSl 1MB 80 + 0% 25% 50% N = 1136 N= 888 N = 809 N = 648 N=316 75% 100% N = 208 N = 365 N = 787 45-49 50-54 II N = 1238 55-59 60-64 65-69 E 70-74 75-79 tí"? 80+ N = 59 N = 54 N = 104 N = 144 N = 175 N = 163 N = 155 N=151 N = 110 0% 25% 50% 75% 100% ra a: 111 localised ■ regional H remote O unknown il localised ■ regional IÜ remote □ unknown Figure 8. Stage distribution of lung cancer in men by age, Slovenia 1981-90. Figure 9. Stage distribution of lung cancer in women by age, Slovenia 1983-90. Epidemiological features of lung cancer in Slovenia 297 256 601 1036 985 710 604 533 263 ;illcell [] aden Figure 10a. Histologic types of lung cancer in men by age Slovenia 1983-90. Figure by age 10b. Histologic types of lung cancer in women , Slovenia 1983-90. llf men Reference 1. Pisani P, Parkin DM, Ferlay J. 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