Lung cancer risk among exsmokers

330 asbestos among such workers. By contrast, employees with small opacities (= 1K);IL0 classification) experienced a significantly raised risk of lung cancer (nine observed deaths v 2.1 expected), even though their exposures to asbestos were similar to the exposures of long term workers without opacities. In this population, excess risk of lung cancer was restricted to workers with x ray film evidence of asbestosis, a finding consistent with the view that asbestos is a lung carcinogen because of its tibrogenicity. Mortality from lung cancer among Sardinian patients with silicosis Carta P, Cocco PL, Casula D. Institure of Occupational Medicine, UniversilyofCagliari, CagliariSard nia. Br J IndMed 1991;48:122-9. The mortality of 724 subjects with silicosis, first diagnosed in 196470 in the Sardinia region of Italy, was followed up through to 31 December 1987. Smoking, occupational history, chest x ray films, and data on lung function were available from clinical records for each member of the cohort. The overall cohort accounted for 10956.5 person-years. The standardised mortality ratios (SMRs) for selected causes of death (International Classification of Diseases (ICD) eighth revision) were based on the age specific regional death rates for each calender year. An excess of deaths for all causes (SMR = 1.40) was found, mainly due to chronic obstructive lung disease, silicosis, and tuberculosis with an upward trend of the SMR with increasing severity of the International Labour Office (ILO) radiological categories. Twenty two subjects died from lung cancer (SMR = 1.29, 95% confidence interval (95% CI) = 0.8-2.0). The risk increased after a 10 and 15 year latency but the SMR never reached statistical significance. No correlation was found between lung cancer and severity of the radiological category, the type of silica (coal or metalliferous mines, quarries etc), or the degree of exposure to silica dust. A significant excess of deaths from lung cancer was found among heavy smokers (SMR = 4.11) and subjects with airflow obstruction (SMR = 2.83). A nested case-control study was planned to investigate whether the association between lung cancer and airway obstruction was due to confounding by smoking. No association was found with the IL0 categories of silicosis or the estimated cumulative exposure to silica. The risk estimate for lung cancer by airflow obstruction after adjusting by cigarette consumption was 2.86 for a mild impairment and 7.23 for a severe obstruction. The results do not show any clear association between exposure to silica, severity of silicosis, and mortality from lung cancer. Other environmental or individual factors may act as confounders in the association between silicosis and lung cancer. Among them, attention should be given to chronic airways obstruction as an independent risk factor for lung cancer in patients with silicosis. Lung cancer risk among exsmokers Sobue T. Suzuki T. Fujimoto I. Matsuda M. Doi 0. Mori T et al. Center forAdultDiseases, l-3-3 Nakamichi, Higashimzri-ku, Osaka537. Jpn J CancerRes 1991;82:273-9. Lung cancer risk among exsmokers according to years since cessation of smoking was assessed by means of a case-control study. The case series consisted of 1,052 lung cancer patients who were newly diagnosed and admitted to eight hospitals in Osaka in 1986-88. Smoking histories were compared with those of 1,111 controls admitted to the same hospitals during the same period without any diagnosis of smoking-related disease. The odds ratio of lung cancer for exsmokers compared tocurrent smokers was estimated tobe 0.90,0.50,0.51,0.59, 0.48 and 0.29, for l-4.5-9, 10-14, 15-19.20-24 and = 25 years after cessation of smoking, respectively. Risk reduction appeared to be greater for those who smoked less than the 1200 cigarette index, compared to those who smoked more. In classification according to histologic type, small cell and large cell carcinoma showed a rapid decrease compared to adenocarcinoma, while squamous cell carcinoma showedan intermediatepattern. Quantitative estimates for reduction of lung cancer risk among exsmokers can be used for projecting lung cancer incidence in the future, by assuming future trends of smoking prevalence, as well as for health education among individual smokers.

Basic biology Association between restriction fragment length polymorphism of the human cytochrome P45OIIEl gene and susceptibility to lung cancer Uematsu F, Kikuchi H, Motomiya M, Abe T, Sagami 1, Ohmachi T et al. Department ofcancerche~therapy andprevention, The Research Instilafe for TuLxrcalosis and Cancer. Tohoku University. 4-1 Seiryomachi, Aoba-ku. Sendai 980. Jpn J Cancer Res 1991;82:254-6. Cytochrome P45OIIEl (P450IIEl) is involved in metabolic activation of carcinogenic nitrosamines, aniline and benzene. We detected a restriction fragment length polymorphism of the human P450IIEl gene with the restriction endonuclease DraI. The population was thus divided into three genotypes, namely, heterozygotes (CD) and two forms of homozygotes (CC and DD). The distribution of these genotypes among lung cancer patients differed from that among controls with statistical significance of Pc0.05(ch&7.01 with 2 degrees of freedom). This result strongly suggests that host susceptibility to lung cancer is associated with the DraI polymorphism of the P4SOIIEl gene. Oliioclonal T lymphocytes infiltrating human lung cancer tissues YoshinoI,YanoT,Yoshikai Y,MurataM,Sugimachi K, KimuraGet al. Departmenr of Virology, Medical Institute ofBioregulafion, Kyushu Universiry, Maidashi 3-1-I. Higashi-ku, Fukuoka 812. Int J Cancer 1991:47:654-S. To clarify the nature of tumor-infiltrating lymphocytes (TILs), we investigated the possible clonality of the T cells in TILs freshly isolated from human primary lung cancer tissues by assessing the rearrangement pattern of the T-cell receptor VCR) gene 8 locus using Southern blotting. First, in phenotypic analysis, TILs represented differentpopulations among corresponding peripheral blood lymphocytes (PBLs) with an increased proportion of CD20+ (B) cells as well as a decreased proportion of CD16* (natural killer) cells, and a variable CD4/CDS ratio. Considering the central role of T cells in immune responses, we analyzed TCR 8 gene rearrangement patterns in TILs and corresponding PBLs from 12 patients. In 10 of the 12 cases, TILs showed one or more TCR gene rearrangement bands with a predominance of the C(O)2 gene, in which 2 types of common rearranged band were observed among the cases with different clinical profiles in terms of histological types and disease stage, with bands at about 9.5 kb in 7 and at 11.5 kb in 8 patients. On the other hand, predominant rearranged bands were hardly detected in corresponding PBLs except in 2 cases. From these results, we conclude thatTILs in lung cancer tissues frequently contain oligcclonal T-cell populations, which were probably sensitized by relatively common antigens at the tumor sites. Characterization and purification of an immunosuppressive factor produced by a small cell lung cancer cell line Ikeda T, Masuno T, Ogura T, Watanabe M, Shirasaka T, Hara H et al. Third Departtnenf of Internal Medicine, Osaka Universiry Medical SchooLI-I-50Fukushima,Fukushima-ku,Osaka553. Jpn JCancerRes 1991:82:332-8. The present study was undertaken to determine whether small cell lung cancer (SCLC) cell lines produce immunosuppressive factors and, if they do, to characterize the factors. The supematants of SCLC cell lines, H69 and N857, inhibited not only the blastogenic response of human peripheral blood lymphocytes (PBL) to phymhemagglutinin or concanavalinA,butalsothecytotoxicactivityoflymphokine-activated killercells. Neither was inhibited by supematants from non-SCLC cell lines PC9, QG56, and A549. The immunosuppressive activity of H69 suparnatant was stable upon heating to 56°C for 60 min, but labile when heated to 70°C for IO min. The activity was abolished after dialysis at pH 2.0 or pH 11.0, but not at pH 4.5 or pH 9.0. Digestion with trypsin or proteinase eliminated the immunosuppressive activity, whereas treatment with neuraminidase, mixed glycosidase,DNase or RNase had no effect, suggesting that the immunosuppressive activity in H69 supematant is due to a protein factor. This H69-derived immunosup-