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Background. Lung cancer is the most common cause of cancer death in the United States, and its incidence has been rising for at least 50 years. Shifts in histologic type and differences in sex and race distribution have accompanied the increased incidence of lung malignancies. Methods. Population-based data regarding lung cancer reported to the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program for the 15-year period 1973-1987 were analyzed. Results. Results indicate that from 1973-1977 to 1983-1987, the age-adjusted rates of lung cancer increased by 30%, with the gain markedly greater in women (70%) than in men (17%). The largest percentage increases in age-adjusted rates were observed for small cell carcinoma and adenocarcinoma (approximately 60% each), with a more modest change for squamous cell carcinoma (+14%). For squamous cell carcinoma, the age-adjusted rates increased substantially for black (65%) and white (70%) women and only slightly for black men (10%), whereas it decreased slightly in recent years for white men. Conclusions. In recent years, adenocarcinoma has replaced squamous cell carcinoma as the most frequent histologic subtype for all sexes and races combined. These shifts in histologic types by sex and race may be related to differences in exposure to tobacco products, dietary factors, environmental or occupational carcinogens, and host characteristics. Increased use of transbronchial and needle biopsy may have also influenced these trends to some extent. Over the study period, 5-year relative survival rate did not change appreciably for lung cancer, suggesting that therapeutic advances have had little effect.

Background. Recent epidemiologic studies have suggested changing patterns of lung cancer incidence by histologic type. The observed time trends have been attributed to a change in the rate of cigarette smoking, changes in exposure to new environmental carcinogens, and changes in the criteria for the histopathologic diagnosis of lung cancer. The current study was designed to examine the incidence patterns of lung cancer by histologic type in Connecticut and to use this information to project the future trend of the disease in this population. Methods. This study was based on all the lung cancer cases reported to the Connecticut Tumor Registry between 1960 and 1989. On the basis of this data set, crude and age-adjusted incidence rates of lung cancer were calculated by histologic type for each sex. The age-specific incidence rates are presented by calendar year and cohort year of birth. A regression model was used to identify birth cohort, period, and age as determinants of the observed time trends. Results. For the overall age-adjusted incidence rates, squamous cell carcinoma and small cell carcinoma have stabilized in men, whereas they are still increasing in women. The incidence of adenocarcinoma has been increasing in both men and women, but there has been a much sharper incidence among females since the mid-1970s. An examination of age-specific incidence rates by birth cohort and the results from age-period-cohort modeling indicate that incidences of all three major histologic types of lung cancer in the recent birth cohorts either have started decreasing (squamous cell carcinoma) or shown a clear reduction in the rate of increase (adenocarcinoma and small cell carcinoma). This study, however, did not indicate an increase of bronchoalveolar lung carcinoma, which was reported by other clinically based studies. Conclusion. While the overall age-adjusted incidence rates showed different incidence patterns for different histologic types of lung cancer, a decreasing or stabilized rate for all three major histologic types of lung cancer was observed in recent birth cohorts in both males and females. The observed incidence pattern is consistent with smoking trends over time including changes in smoking prevalence and the consumption of low tar and filter cigarettes. It is expected that if the current trend in tobacco smoking continues and if there are no major changes in other risk factors for lung cancer, a forthcoming stabilization or decrease in the rate of lung cancer incidence for all major histologic types (including adenocarcinoma) in both sexes in Connecticut could be anticipated.

Cigarette smoking habits have changed in the United States over the past few decades. Many people have quit smoking, and many others are smoking cigarettes with lower amounts of tar. A survey of 505 cases of lung cancer suggests that the types of cancers being diagnosed are changing as well, and most likely reflect the changes in smoking habits. Cigarette smoking has been found to be associated with an increased risk of bronchogenic cancer. These cancers arise in the bronchi, the airways which carry air from the trachea into the lung tissue itself. Cancers arising in lung tissues outside the bronchi do not appear to be associated with smoking. Of the cancers occurring prior to 1978, 69.3 percent were of the type thought to be related to smoking. In contrast, 57.3 percent of the cancers occurring between 1986 and 1989 were of the same types. Conversely, peripheral cancers occurring outside the bronchi rose from 30.7 to 42.0 percent of the total lung cancer cases during this same interval. Of the various types of lung cancer, the greatest proportional increase was in the bronchoalveolar type, which rose from 9.3 to 20.3 percent of the total lung cancer cases. Bronchoalveolar cancer is apparently unrelated to smoking. In the present series of patients, 35.4 percent of the peripheral cancers involved scar tissue. This scar tissue may have resulted from tuberculosis or from damage resulting from the obstruction of a blood vessel. Lung cancers are classified on the basis of the structure visible under the microscope, as well as on their site of origin in the lungs; the squamous cell and oat cell carcinomas are both less likely to be seen with the decrease in smoking. Adenocarcinomas as well as some other types are likely to constitute a greater fraction of the cases of lung cancer in the future. (Consumer Summary produced by Reliance Medical Information, Inc.)

Lung cancer accounts for nearly six percent of all deaths in the United States. By far the most important risk factor is cigarette smoking, which not only contributes to the development of lung cancer, but tends to obscure the earliest symptoms, so that by the time the patient seeks medical care, the disease is already incurable. Clinical evidence suggests that the detection of early lung cancer in its asymptomatic stages would provide better chances for survival. However, it does not automatically follow that screening for lung cancer will lead to improved survival. For example, it must be demonstrated that the screening program will detect a significant proportion of cancers in the earliest stages. Furthermore, a screening program must be economical, and the cost and distress associated with false positive results must be minimized. Several major trials have been conducted to determine if regular screening for lung cancer using chest X-rays and/or sputum examination is practical. These major trials were established by the National Cancer Institute and conducted at Johns Hopkins University, Memorial Sloan-Kettering Cancer Center, and the Mayo Clinic. The authors review the results of the study, which involved 9,211 men, all heavy smokers, who were followed for over a decade. X-ray and sputum cytological screening examinations were performed for 4,618 men, while the control group of 4,593 men were advised to have yearly X-rays, but were not reminded or prompted to participate in screening. The subjects were, of course, contacted annually to determine their health status. Surveillance of nearly 38,000 person-years in each group was accumulated. In the group receiving regular check-ups, the rate of lung cancer detection was significantly better, the cancers were more likely to be detected at a stage when surgery was still possible, and the length of survival was longer. However, the patients still died of lung cancer, and there were no significant differences between the two groups in overall mortality from lung cancer. The results suggest that mass screenings for lung cancer, at least at this time, are not warranted. (Consumer Summary produced by Reliance Medical Information, Inc.)