Letter: Adenocarcinoma and smoking

Cancer in the respiratory organs of Swedish farmers

In a cohort of 254,417 male Swedish farmers (4,330,717 person-years) the incidence of cancer of the respiratory organs was compared to a reference cohort of 1,725,845 men (30,131,664 person-years) employed in other economic activities than agriculture or forestry. In the study cohort 1450 cases of cancer in the respiratory organs were found in 1961 to 1979 resulting in an estimated relative risk (RR) of 0.38 (95% confidence interval [CI]: 0.36-0.40). For cancer of trachea, bronchus and lung, the decreased risk was equal for adenocarcinoma and squamous cell carcinoma. No time related trend in RR for any of the histologic subtypes could be seen. However, for squamous cell carcinoma in nose and nasal sinuses RR has increased from 0.42 (95% CI: 0.20-0.80) in 1961 to 1966 to 2.06 (95% CI: 1.22-3.50) in 1974 to 1979.

Occupation and lung cancer risk. An analysis by histologic subtypes

The relationships between cigarette smoking, occupational exposures, dietary vitamin A and lung cancer is explored in a case-control study. The study is based on 1002 primary lung cancers among white men and 1119 white male controls between 35 and 79 years of age admitted to Roswell Park Memorial Institute from 1957 to 1965. Four hundred sixty-four lung cancer cases were classified as one of the three major histologic cell types: squamous, small cell, or adenocarcinoma. Each of the three main histologic types displayed a statistically significant trend of increasing risk associated with increasing consumption of cigarettes with the strongest relationship being seen for small cell carcinoma (odds ratio for 40+ pack-years = 17.5) and the weakest with adenocarcinoma (odds ratio for 40+ pack-years = 6.7). Increasing risk for squamous cell cancer was seen with increasing duration of exposure to all lung carcinogens, asbestos, and aromatic hydrocarbons. Small cell carcinomas were not associated with any of the occupational exposure categories studied with the exception of asbestos exposure in light smokers. Increasing risk of adenocarcinoma was seen with increasing duration of employment in occupations with potential exposure, but only for light smokers. Dietary vitamin A consumption did not confound the occupational associations. Hypotheses have been generated regarding interplay of risk factors in the etiology of different histologic subtypes of lung cancer. Studies of specific histologic types of lung cancer are needed to elucidate the role of various environmental and occupational risk factors.

Lung cancer in Hong Kong Chinese: mortality and histological types, 1973-1982

The histological types of lung cancer in Hong Kong Chinese in both sexes are presented. When the 1981 WHO Classification is used instead of the 1967 WHO Classification, more than half of the large cell carcinoma is retyped into the adenocarcinoma group. The proportion of large cell carcinoma thus decreases from 14.7% to 6.9% in the male and from 10.0% to 4.4% in the female. Compared to the 1948-1962 report from the same Department, there is a shift of the peak age distribution from the 6th decade to the 7th decade. Compared to the 1960-1972 report from the same Department, there is a significant increase in the relative frequency of adenocarcinoma in both sexes, from 15.6% to 25.8% in the male and 34.3% to 49.6% in the female. Adenocarcinoma continues to be the most common histological type in females and it is becoming the commonest type in males. It is also found in the present series that in the male, the proportion of adenocarcinoma decreases with increasing age, from 60% in the third decade to 26.6% in the eighth decade. In spite of the high female lung cancer mortality rate and therefore low male:female ratio of about 2:1, there is a tendency for this ratio to increase over the years. It is speculated that factors other than active cigarette smoking may be responsible for the peculiar and changing histological pattern and the female predominance in lung cancer in Hong Kong Chinese.

Clinical features of bronchogenic carcinoma in Hong Kong. Review of 480 patients

A retrospective study was made of 480 Chinese patients with proven bronchogenic carcinoma, the top cancer in Hong Kong. The male-to-female sex ratio was low (1.9:1) and the female mortality rate ranked amongst the world's highest. The four major histologic types accounted for 87% of the cases: 39% epidermoid, 12% small cell anaplastic, 29% adenocarcinoma, and 7% large cell anaplastic. History of smoking was associated with epidermoid and small cell anaplastic carcinoma only. The commonest symptoms were anorexia and malaise (67%) and cough (51%). Overall our patients presented late and only 30 (6%) had curative surgery. The relatively rare occurrence of deep vein thrombosis (0.7%) is in keeping with the known low incidence of venous thrombosis in Chinese. Adenocarcinoma was a distinct group characterized by its preponderance in females (43%), lack of association with smoking habit (61% female cases being nonsmokers), high frequency of neurologic manifestation (21%) and clinical, roentgenographic, and bronchoscopic features of a predominantly centrally situated tumor. Possible etiologic factors for the high and still increasing incidence of adenocarcinoma are discussed.

Two primary carcinomas of the lung: adenocarcinoma and a metachronous squamous cell carcinoma. A case report and review of the literature

The case of a patient who underwent a left lower lobe lobectomy for adenocarcinoma of the lung and developed a metachronous squamous cell carcinoma of the right lung eight years later, is presented. The unusual nature of the case is emphasized utilizing a review of the literature. The criteria for diagnosing metachronous carcinomas are presented and a unified terminology for such cases is proposed. The requirement for life-long follow-up of any patient with cancer is emphasized.

Lung cancer in Greenland--selected epidemiological, pathological, and clinical aspects

One hundred and seven cases of lung cancer were first diagnosed among indigenous Greenlanders during the 25 years from 1955 to 1979. Compared with the Danish population, relative risk of lung cancer among male Greenlanders increased from 0.4 in 1955-1959 to 1.1 in 1975-1979. Relative risk among women increased from 0.7 to 2.1. The age-adjusted rate for women during the period 1975-1979 is one of the highest on record. This increase in lung-cancer risk followed a sharp rise in the use of cigarettes in the general population. An association with cigarette consumption was also suggested by tumor histology and location. A synergistic role of other risk hazards is possible. Local factors arising from previous tuberculosis involvement may have favored lung cancer development in men. More than 2/3 of the cases of lung cancer diagnosed between 1955 and 1974 were brought to medical attention because of clinical symptoms although most of the population was screened annually or biannually for tuberculosis. Intervention through screening had little impact on the overall very low survival rate.

Ankylosing spondylitis and adenocarcinoma of the lung

A man with long standing and severe ankylosing spondylitis, treated with radiotherapy, developed a primary adenocarcinoma of the lung in an area of apical fibrosis. The significance of this is discussed and the literature reviewed.

The changing histopathology of lung cancer: a review of 1682 cases

We have reviewed the histopathology of lung cancer patients seen over the past 13 years at RPMI. Assessment of this data indicates that adenocarcinoma is becoming progressively more prevalent as related to the other forms of lung cancer. Factors which in part may account for this increased prevalence are: 1) changes in criteria for reading histopathology of lung cancer, particularly since 1967; 2) the increased incidence of lung cancer among the female population who have a propensity for adenocarcinoma; and 3) occupational and environmental factors. In 1974 adenocarcinoma for the first time became the most prevalent type of lung cancer at RPMI. Whatever the reason, if our data are truly representative of a national trend, adenocarcinoma will soon become the most prevalent type of lung cancer in the United States. This fact may result in an increasing death rate since the present 18-month survival rate for adenocarcinoma is substantially less than for squamous cell carcinoma, which has in the past been the prevalent form of the disease. As the smoking habits of women more closely approximate those of men, we expect that the incidence and mortality of lung cancer will prove to be quite similar in both sexes.