Document jgQo0K3XgQx9EwvDrewNaab4Q

Analysis of Cancer Risk Related to Longitudinal Information on Smoking Habits Suminori Akiba Department of Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan Radiation Effects Research Foundation (RERF) has followed the RERF Life Span Study (LSS) cohort consisting of atomic bomb survivors and unexposed subjects for more than 40 years. The information on their lifestyles, including smoking habits, has been collected in the past 25 years through two mail surveys of the entire LSS cohort and three interview surveys of a subcohort for the biennial medical examination program. In the present study an attempt was made to consolidate the information on smoking habits obtained from the five serial surveys, and then a risk analysis was conducted to evaluate the effect of updating the smoking information on the smoking-related risk estimates for lung cancer. The estimates of smokingrelated risk became larger and estimates of dose-response became sharper by updating smoking information using all of the data obtained from the five serial surveys. Analyses were also conducted for cancer sites other than lung. The differences in risk estimates between the two approaches were not as evident for the other cancer sites as for lung. - Environ Health Perspect(Suppl 8):15-20 (1994) Key words: RERF Life Span Study, risk assessment, smoking, lung cancer Introduction In our previous studies, (1,2) we compared the smoking-related risk of lung cancer in the Six-Prefecture Cohort Study, the largescale Japanese cohort study conducted by Hirayama and his colleagues, with that in the British physicians' cohort study (3). We concluded that the relatively low lung cancer risk among cigarette smokers in the Japanese cohort can be explained, at least partially, by the cigarette shortage that lasted for about six years during and immediately after the Second World War. Another interesting difference between the two cohorts noted in our analysis was the strength of association between daily cigarette consumption and lung cancer risk: the dose-response relationship was sharper in the latter study than in the former. A possible explanation for the observed discrepancy was the difference in the fashion in which information was collected on smoking habits, which can change over time. In the Japanese study, the information was collected by a single survey conducted in 1965; therefore, we unavoidably had to ignore the possible changes of smoking habits over time. In the British study, serial surveys were conducted to update information on smoking habits. Since direct evaluation was not possible in the Six-Prefecture Cohort Study, we used the data obtained This paper was presented at the 4th Japan-US Biostatistics Conference on the Study of Human Cancer held 9-11 November 1992 in Tokyo, Japan. Address correspondence to Suminori Akiba, Department of Public Health, Kagoshima University School of Medicine, 8-35-1 Sakuragaoka, Kagoshima 890 Japan. from another large-scale cohort study in Japan, the Life Span Study (LSS) of atomic bomb survivors in Hiroshima and Nagasaki. This study covers the observation period, 1966 to 1981, in our analysis of the Six-Prefecture Cohort Study data. Radiation Effects Research Foundation (RERF) has followed the LSS cohort consisting of atomic bomb survivors and unexposed subjects for more than 40 years (4). Information has been collected on their lifestyles, including smoking habits, in the past 25 years through two mail surveys of the entire LSS cohort and three interview surveys of its subcohort for the biennial medical examination program (5). In the present study, information on smoking habits obtained from the five sources was consolidated. Then risk analysis of cancer of the lung and the other major sites was conducted to compare the smoking-related risk estimates obtained from two approaches; one with smoking information limited to that available from the first survey, and the other incorporating all of the available information. Subjects and Methods The LSS cohort of the RERF originally consisted of 100,000 atomic bomb survivors and nonexposed control subjects. It was expanded around 1968 and in 1985 by adding about 10,000 atomic bomb survivors to the non-Adult Health Survey (AHS) subpopulation of the LSS population each time. Persons already deceased also were included in the expansion of the cohort (5). The cohort now consists of about 120,000 subjects including 27,000 nonexposed controls, i.e., Not In City (NIC) subjects. The information on smoking was obtained from the five sources listed in Table 1. A subject in the AHS subcohort could have come under study in three interview surveys and two mail surveys at the maximum. In this study, however, the data obtained from the 1965 mail survey for male AHS subjects were not used if they responded to the 1964 to 1968 interview survey. Information on cancer incidence and mortality follow-up were obtained from the RERF tumor registry and mortality database. Details of these data are given elsewhere (4,6). The tumor classification used in this study is given in Appendix Table 1. Individual radiation doses from exposure to atomic bombing were estimated using the latest version of the DS86 (7). Shielded kerma was used in all analyses reported in this article. Statistical Methods Poisson regression models were used to fit loglinear relative risk (RR) and linear excess RR models. Maximum likelihood parameter estimates, 95% confidence intervals, and likelihood ratio tests for nested models were obtained using the AMFIT regression program (8). The confidence intervals presented in this article were calculated by likelihood methods using large-sample approximations unless otherwise specified (9). Using DATAB computer program (8), the person-years and the number of cancer cases were aggregated and stratified by city, sex, population group (AHS sample or not), atomic bomb exposure (NIC or 0-, 0.01-, 1.0+ Gy, and dose unknown), 10- Environmental Health Perspectives 15 S. AKIBA Table 1. Sources of smoking information. Survey Period Subjects Smoking status' Daily cigarette consumption Age started smoking Age stopped smoking Interview Survey 1 Survey 2 Survey 3 Mail Survey 1-1 Survey 1-2 Survey 2-1 Survey 2-2 1963-1964 1964-1968 1968-1970 1965 1969 1979 1980 AHS participants AHS participants AHS participants LSS men, aged 4069 in 1965 All LSS women, except AHS All LSS men, except NIC All LSS women, except NIC + +b + +b +b + + + + + CategorizedC + + + + - + + + + + +d + + AHS, Adult Health Survey; LSS Life Span Study; NIC, not in city. "Never smoked, stopped smoking, or currently smoking. bAlthough current status of smoking was not asked, it can be estimated since questions on daily cigarette consumption dCalculated from year since the cessation of smoking. for current and ex-smokers were asked. CCategorized according to 1-4, 5-9, 10-14, 15-19, and 20+ g/day. year intervals of year of birth (before 1884, 1885-1894,...,1935 or later) and 5-year intervals of attained age (less than 39, 40-44, 80 or older), as well as smokingrelated variables. The log-linear RR model used in our analysis was as follows: Rij= Rioexp(PjGj), [1] where i is the stratum in the cross- classification of city, sex, population group, atomic bomb exposure status, year of birth, and attained age; and j is the category of exposure variable, e.g., number of cigarettes smoked per day. R;, is the cancer incidence rate for nonsmokers and G.. is the dummy variable for the exposure group j. Also used in the analysis was the linear excess RR model of the form Rij-= Ri-o(I +jDij) ' [2] where Di., for example, is the stratumspecific average daily consumption of ciga- rettes. Results After consolidation of information on smoking, there were 15,304 AHS subjects and 46,201 nonAHS LSS subjects for whom there were smoking data. For 42% of the subjects, information on smoking habits had been obtained at more than one 35,911 0 QKI U 0 E z -_ 5,175 4,168 ~~~8% 7# 667 2 345 Number of surveys for an individual Figure 1. Number of smoking habit surveys. time point (Figure 1). All the surveys except the 1979 to 1980 mail survey were conducted during the period of 1963 to 1970. A total of 19,284 subjects responded to one of the surveys conducted in 1963 to 1970 and to the 1979 to 1980 mail surveys. Although the format of questions on cigarette smoking habits differed between the surveys, they were so constructed that the current smoking habits could be cate- gorized into three groups: never smoked, stopped smoking, and currently smoking. An exception was the 1963 to 1964 interview survey where ex-smokers could not be distinguished from those who had never smoked. In addition, in this survey it was hard to distinguish between cigarette smokers and smokers of other tobaccos. Those who answered as nonsmokers in the 1963 to 1964 survey, to which about 15% of the subjects analyzed in this article responded, were considered never to have smoked, since smoking cessation was not common in Japan at that time. As shown in Table 2, there are nine possible combinations in the smoking habit variables taken from any two subsequent surveys. Since the combinations of E->N and S->N are not possible if the answers were correct, they were replaced with E-E and S-*E, respectively. These conflicting combinations, however, were infrequent. When serial information on smoking is to be used in risk analysis, analysts are forced to face a problem that sometimes is ignored when the risk is to be analyzed in example 1. period 1 period 2 t Survey 1 t Survey 2 example 2. period 1 period 3 t Survey 3 end of follow-up period 2 Survey 1 Survey 2 Figure 2. Study design. terms of smoking information obtained at a single time point. The question is the length of the period to be allowed between the time when data on smoking habits were obtained and the beginning of the subsequent observation period (Figure 2). A three-year lag time was allowed in our risk analysis: the smoking habits in one survey were related to the observation period start- ing three years after the survey and ending three years after the next survey or at the end of follow-up, December 31, 1987. Table 3 compares the results obtained from two data sets, one with the informa- tion on smoking from the first survey, the other with all the information available. Although the total numbers of subjects are the same between the two surveys, the latter tended to include smaller numbers of those who had never smoked or who were cur- rent smokers and a larger number of ex- smokers, due to the data correction made after consolidating multiple data sets. The relative risk of lung cancer among the cur- rent smokers and ex-smokers identified by a single survey was slightly lower than the risk level identified from the analysis using all the available information. Table 4 shows the relative risk estimates for lung cancer according to daily cigarette consumption. The number of subjects who Table 2. Combination of the results from two surveys. Male, % Female, % N->N N-eE N-4S E-A E-4E E-4S S-A S-+E S--*S Total % 14.6 3.1 1.7 0.6 5.2 1.2 0.9 11.6 61.1 100.0 83.5 0.9 2.3 0.3 0.4 0.3 0.9 1.4 10.0 100.0 N, those who have never smoked; E, ex-smokers; S, current smokers. 16 Environmental Health Perspectives ANALYSIS OF CANCER RISK Table 3. Comparison of lung cancer risk associated with smoking between the two approaches in the use of smoking information Data source Smoking habits Never Ex-smoker Current smoker Male Number of cancer cases First survey only All surveys Person years First survey only All surveys Crude rate (10- ) First survey only All surveys Relative risk (95%CI) First survey only All surveys Female Number of cancer cases First survey only All surveys Person years First survey only All surveys Crude rate (10- ) First survey only All surveys Relative risk (95%CI) First survey only All surveys 24 18 41,560 35,833 58 50 1.Oa 1.Oa 123 116 366,493 359,850 34 32 1.Oa 1.Oa 35 48 25,755 36,303 136 132 2.3 (1.4-3.9) 2.5 (1.5-4.3) 4 9 8,740 13,942 46 65 1.0 (0.3-2.4) 1.4 (0.7-2.6) 352 345 176,200 171,379 200 201 4.2 (2.8-?)" 5.1 (3.3-?)" 72 74 49,794 51,237 145 144 3.6 (2.6-4.8) 3.9 (2.9-5.3) b95%a Reference category for relative risk estimation. bound could not be obtained. Table 4. Lung cancer risk according to daily cigarette consumption-a comparison of the two approaches in the use of smoking information Data source No. cigarettes smoked per da8 1-14 15-24 25+ Male Number of cancer cases First survey All surveys Person years First survey All surveys Relative risk' (95%CI) First survey only All surveys Femaled Femaler No.cancercases First survey AlPsurveys Person years First survey All surveys Relative risk (95%C) First survey All surveys 116 104 67,643 59,893 3.0 (2.0-4.8) 3.5 (2.2-6.0) 54 54 40,228 38,968 3.2 (2.3-4.4) 3.6 (2.6-5.0) 200 178 86,890 82,289 5.3 (3.5-?)c 6.1 (3.9-?)c 17 17 8,274 10,284 6.8 (3.9-1 1.2) 5.8 (3.3-9.5) 36 63 21,066 28,351 5.6 (3.3-9.6) 9.1 (5.4-15.9) "Ex-smokers were excluded from the analysis. bThe reference category is that consisting of those who had never smoked, shown in Table 2. c95% bound could not be obtained. dIn females, daily cigarette consumption category of 15-24 nd 25+ were combined. had never smoked, who constituted the reference category, are not presented in this table but they were used in the analysis. The numbers of females who smoked 15-24 cigarettes per day and those who smoked 25 or more cigarettes per day were combined since the latter category had only a small number of subjects. The relative risk increased markedly among males smoking 25 or more cigarettes per day, as measured by the updated smoking information. No evident change was noted in the analysis of the data for females. In addition to lung cancer, analyses were conducted for the other major cancer sites (Table 5). Although differences were noted for cancers of some sites, the 95% confidence intervals for the estimates for those sites were also large. The estimates given here were not affected greatly by changing the lag time for risk analysis from 0 to 5 years. Discussion The results obtained in this study showed that the estimates for lung cancer risk can be increased by updating smoking information using the data from a series of surveys. The proportion of male smokers in Japan started to decrease in the mid-1960s, when more than 80% of males were smokers, and the trend is still unabated (10). According to a recent survey (11), 60% of male respondents were smokers. On the other hand, the proportion of female smokers has remained at 10 to 15% over the last three decades, for which statistics have been available (10). In such a situa- tion, not a small number of the male smokers identified at the beginning of the follow-up period are expected to have stopped smoking during the follow-up period. Therefore, the risk estimates for male smokers was thought to be underestimated if information on smoking habits was obtained by a single survey in the mid1960s, and that cohort subsequently was followed. The same is true for the relative risk estimates for males who were heavy smokers, since the amount smoked per day is thought to have decreased over time based on two observations: the amount of cigarettes smoked was smaller for older birth cohorts, and it decreased with age in the same birth cohort (RERF, unpublished data). The effect of updating information on smoking can be affected by the lag time during which the effects of changes in smoking habits on cancer risk become noticeable. That period can be different for different cancer sites. The effect on lung cancer of cessation of smoking is reported Volume 102, Supplement 8, November 1994 17 S. AKIBA Table 5. Smoking habits and cancer risk in various cancer sites. Cancer site Number of cases Male Female Ex-smoker First survey Relative risk and 95% Cla,b for Current smoker All surveys First survey Allsurveys All cancer 2817 Pharynx 42 Esophagus 83 Stomach 966 Colon 172 Rectum 122 Liver 271 Gallbladder 63 Pancreas 76 Nasal cavity 19 Larynx 41 Lung 411 Skin (excl. melanoma) 39 Breast 5 Uterus, NOS - Cervix uteri - Corpus uteri - Ovary - Prostate 113 Bladder 112 Kidney 28 Ureter 15 Brain 14 Thyroid 15 Lymphoma 63 Multiple Myeloma 21 Leukemia 43 2435 27 20 547 152 96 120 98 74 7 5 199 57 340 19 195 57 71 - 33 18 8 10 74 55 31 25 1.1 1.0-1.3 0.4 0.1-1.4 2.1 0.8-5.0 1.3 1.1-1.6 0.9 0.5-1.4 1.0 0.6-1.8 1.4 0.9-2.1 0.9 0.4-1.8 0.9 0.4-1.9 2.9 0.4-15.8 13.6 1.8 1.2-2.6 1.5 0.6-3.3 1.0 0.4-2.0 2.2 0.1-11.8 0.8 0.2-2.1 0.8 0.04-3.6 0.7 0.04-3.3 0.7 0.3-1.4 1.2 0.5-2.5 0.5 0.1-1.9 0.6 0.03-3.7 0.8 0.1-3.5 00.6 0.2-1.6 0.6 0.1-2.0 0.8 0.3-2.2 1.2 1.1-1.4 0.4 0.1-1.2 2.8 1.3-6.3 1.3 1.1-1.6 0.9 0.6-1.4 1.3 0.8-2.0 1.6 1.1-2.3 0.9 0.5-1.7 0.8 0.4-1.6 2.9 0.5>100 1.9 1.3-2.6 1.1 0.5-2.2 1.2 0.7-1.9 1.6 0.1-8.3 1.5 0.7-2.8 1.0 0.2-3.3 0.8 0.1-2.7 0.8 0.5-1.6 1.4 0.7-2.8 0.9 0.3-2.6 1.4 0.3-5.5 0.8 0.2-3.1 0.8 0.2-2.2 1.2 0.5-2.4 0.8 0.3-2.2 0.9 0.4-2.0 1.5 1.4-1.7 1.2 0.63.1 1.7- 1.4 1.2-1.6 1.1 0.8-1.4 1.0 0.7-1.4 1.8 1.4-2.4 1.4 0.9-2.1 1.2 0.8-1.9 4.5 1.432.1 6.13.7 2.9-4.7 1.2 0.7-2.0 1.1 0.8-1.5 2.1 0.6-6.1 1.7 1.2-2.4 1.0 0.4-2.0 1.0 0.5-1.9 0.9 0.6-1.5 2.2 1.4-3.6 1.0 0.4- 1.7 0.50.6 0.21.1 0.6-2.0 1.4 0.9-2.3 1.0 0.5-2.1 0.9 0.5-1.7 1.6 1.5-1.7 1.1 0.63.3 1.71.4 1.2-1.7 1.2 0.9-1.6 1.0 0.7-1.4 1.8 1.4-2.5 1.5 1.0-2.2 1.2 0.8-1.9 4.0 1.2>100 4.1 3.3-5.3 1.2 0.7-2.0 1.1 0.8-1.5 2.0 0.6-5.8 1.6 1.1-2.3 0.8 0.3-1.7 1.3 0.6-2.3 1.0 0.7-1.7 2.6 1.6-4.5 1.1 0.5-2.5 1.3 0.40.5 0.2-1.5 1.0 0.5-1.7 1.6 0.9-2.6 1.0 0.4-2.0 0.7 0.4-1.4 "When 95% confidence bound could not be obtained, the corresponding column was left blank. b Relative risk and 95% confidence interval with reference category being the group of never smokers. The cancer sites with fewer than 15 cases were excluded from this table. Those cancer sites are other digestive organs (15), other respiratory organs (11), bones (7), soft tissue (11), cutaneous melanoma (3), other female genital organs (11), testis and other male genital organs (6), other urinary organs (9), eye (1), pituitary, pineal gland and other endocrine organs (6), and unknown sites (100). to become apparent within about 5 years (12). In our analysis, we assumed the lag time to be three years, as Doll and Peto (3) did in their analysis of British physicians' data. The results presented in this artcle were not strongly affected by changing the lag time from 0 to 5 years. As is often pointed out, the relative risk of lung cancer in terms of daily cigarette consumption is much lower than that reported in the US and in Western European countries. At the Japan-US biostatistics seminar in 1989, we reported the results of a reanalysis of the Six-Prefecture Cohort Study data that confirmed the notion (1). In that reanalysis of cancer risk during the period 1966 to 1981, we also noted that the risk associated with smoking increased markedly in the mid-1970s in all the birth-year groups. The observation could not be explained by the increase in the cumulative amount of cigarettes smoked with aging of the cohort since the risk was more strongly affected by calendar time than attained age. The risk appeared to increase around the mid-1970s in all the birth cohorts. A subsequent analysis of the Six-Prefecture Cohort data by Mizuno et al. (2) showed that the low lung cancer risk in Japan can be explained by the cigarette shortage, which lasted for about 6 years during and immediately after the Second World War. They reported that lung cancer mortality among males smoking 20 cigarettes per day in the Six-Prefecture Cohort can be expressed in the equation: 1.9 x 10-1' x (duration of cigarette smok- ing in years - 5.8 years) (4,5). This was quite similar to the result obtained from the British physicians' data (3), where the lung cancer incidence among male physicians who smoked 20 cigarettes per day was 1.8 x 10-10 x (duration of cigarette smoking in years) (4,5). The results obtained for heavier smokers and lighter smokers were, however, not as good as for those smoking around 20 cigarettes per day: after adjustment for the cigarette shortage, the lung cancer mortality became lower for heavy smokers and higher for light smokers when compared with the British data. One possibility for this discrepancy is the difference in the way the smoking information was collected: in the Japanese cohort, the information was obtained at the beginning of the follow-up period, while in the British cohort, serial surveys were conducted and the information was updated. Since direct evaluation was impossible in the Six-Prefecture Cohort, we examined this problem using the data obtained in the LSS cohort of the RERF. As shown in this article, the relative risk in the heavy smokers was increased, based on our updating of the smoking information, while that in the light and medium smokers changed only slightly. This suggested the possibility that the risks for male heavy smokers in the Six Prefecture Cohort would become more similar to the risks for the British cohort if the smoking information were appropriately updated. The smoking-related risks for various cancer sites obtained in this study were similar to those reported in our previous report using the mortality follow-up data obtained from the Six-Prefecture Cohort study in Japan (1). In the present study, however, the association of cancers of the pharynx and pancreas with smoking habits could not be confirmed. Cancers of the 18 Environmental Health Perspectives ANALYSIS OF CANCER RISK skin, uterine corpus, ovary, kidney, ureter, and thyroid, as well as malignant lymphoma, multiple myeloma, and leukemia -all of which were newly analyzed in this study- did not show any significant association with smoking. A marginally significant result in the statistical test was found in the association of smoking with lymphomas, most of which were nonHodgkin's lymphoma. This result is inter- esting since non-Hodgkin's lymphoma was recently reported to be related to smoking by a study of 17,633 US white male insurance policy holders (13). Further investigations on this observation are certainly warranted. In this study, subjects with smoking information from multiple surveys comprised less than half of the entire population. The exclusion of those with a single response would, however, introduce a bias in risk analysis since nonresponse could be related to the health condition of the sub- jects. The health conditions related to cancer can cause changes in smoking habits. It is unlikely, however, that the correlation affected the results substantially in this study since the incidence data were used and cancer risk analysis was conducted after excluding the first three years of the observation interval corresponding to each survey (Figure 2). Appendix Table Al. Tumor classification. Cancer sites Topography Pharynx (incl. buccal cavity) Esophagus Stomach Colon Rectum Liver Gallbladder (incl. biliary) Pancreas Other gastrointestinal Nasal cavity (incl. ear, sinuses) Larynx Lung (incl. trachea, bronchus) Other respiratory organs Bones (incl. joints) Soft tissues Melanomas Other skin Breast Cervix uteri Corpus uteri Uterus, NOS Ovary Other female genital organs Prostate Testis Other male genital organs Urinary bladder Kidney Ureter (incl. renal pelvis) Other urinary organs Eye Brain (incl. nervous system)a Thyroid Pituitary and pineal glanda Other endocrine organs Lymphomas (incl. ATL) Multiple myeloma Leukemias 1400-1499 1500-1509 1510-1519 1530-1539 1540 1550 1551,1560 1570-1579 152_,158_,159 1600-1609 1610-1619 1620,1622-1629 163_,1642-1659 1700-1709 1641,1710-1719 1730-1739 1730-1739 1740-1759 1800-1809 1820-1828 1799 1830 1819,1832 1859 1860-1869 1871-1879 1880-1889 1890 1891,1892 1893-1899 190 191 _192_ 1939 1943,1944 1640,1940 Any Any Any ' Including in situ carcinomas and benign tumors. ICD-0 Codes Morphology Excl. 959--994_ Excl. 959--994_ Excl. 959_--994_ Excl. 959--994_ Excl. 959_--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959_--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959_--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959_ - 994_ Incl. 8720 - 8790 Excl. 8720 - 8790 (959 - 963, 970_) Excl. 959--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959_--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959_--994_ Excl. 959_--994_ Excl. 959--994_ Excl. 959--994_ Excl. 959_--994_ Excl. 959--994_ Excl. 959_--994_ Excl. 959_- 994 Excl. 959_- 994_ Incl. 959 - 976_ Incl. 973_ Excl. 971--973_ Incl. 9800_--994_ REFERENCES 1. Akiba S, Hirayama T. Cigarette smoking and cancer mortality risk in Japanese men and women-results from reanalysis of the Six-Prefecture Cohort study data. Environ Health Perspect 87:9-26 (1990). 2. Mizuno S, Akiba S, Hirayama T. Lung cancer comparison among male smokers between the "Six-prefecture Cohort" in Japan and the British Physicians' cohort. Jpn J Cancer Res 80:1165-1170 (1989). 3. Doll R, Peto R. Cigarette smoking and bronchial carcinoma: dose and time relationships among regular smokers and lifelong non-smokers. J Epidemiol Commun Health 32:303-313 (1978). 4. Shimizu Y, Kato H, Schull WJ. Studies of the mortality of Abomb survivors. Report 9. Mortality, 1950-1985: Part 2. Cancer mortality based on the recently revised doses (DS86). Radiat Res 121:120-141 (1990). 5. Kato H. Data resources for Life Span Study. Atomic bomb survivor data: utilization and analysis. Proceedings of a SIMS Conference Alta Utah, 1983 Philadelphia:SIAM, 1984. 6. Thompson D, Mabuchi K, Ron E, Soda M, Tokunaga M, Ochikubo S, Sugimoto S, Ikeda T, Terasaki M, Izumi S, Preston D. Solid tumor incidence in A-bomb survivors, 1958-87. RERF Technical Report 5-92 (1992). 7. Fujita S. Versions of DS86. RERF Update 1:3 (1989). 8. Preston DL, Lubin JH, Pierce DA. In: Epicure User's Guide. Seattle:Hirosoft International, 1991. 9. Cox DR, Hinckley DV. Theoretical Statistics. London: Capman and Hall, 1974. 10. Tominaga S. Smoking and cancer patterns and trends in Japan. In: Tobacco: A Major International Health Hazard (Zaridze DG, Peto R, eds). IARC Scientific Publications No. 74, Lyon:International Agency for Cancer Research, 1986; 103-1 13. 11. Japan Tobacco. National survey of proportion of smokers, 1990: a summary of results, 1990. 12. Office of Smoking and Health, US Department of Health and Human Services. The health consequence of smoking: cancer, a report of the Surgeon General Washington:US Government Printing Office, 1982. 13. Linet MS, Mclaughlin JK, Hsing AW, Wacholder S, Chien HTC, Schuman LM, Bjelke E, Blot WJ. Is cigarette smoking a risk factor for non-Hodgkin's lymphoma or multiple myeloma-results from the Lutheran Brotherhood Cohort Study. Leuk Research 16:6-7 (1992). 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