Tobacco Documents Online

A PRELIMINARY DISCUSSION ON LUNG CANCER HISTOLOGICAL TYPES VARIATION AT DIFFERENT PERIODS IN GUANGZHOU Li, Lie; Huang, Shuwei; Lu, Zhenjie; Wan Guangeai Dept. of Pathology, Guanzhou Medical College [ABSTRACT] A total of 1048 lung cancer cases obtained from the First Affiliated Hospital of Guangzhou Medical College from 1978 to 1994 were reviewed in this paper. Using WHO's lung cancer classification, the proportion of squamous cell carcinoma (SCC) was 54.68%, for adenocarcinoma 32.44%, for small cell carcinoma 5.15%, and for large cell carcinoma 1.91%. These data are compared to those in a former paper,1 for the rate of SCC and adenocarcinoma. The total lung cancer cases are nearly the same. We divided the period into three sub-periods (1978 to 1984, 1985 to 1989 and 1990 to 1994). The percentage of SCC of the total cases was 68.72%, 57.99% and 38.8% for the three sub-periods, respec- tively. The rate of adenocarcinoma, however, was 19.43$, 29.1% and 47.49%, for the three sub-periods, respectively. Thus, the results showed that the rate of SCC decreased progressively during the past two decades. On the other hand, the rate of adenocarcinoma increased markedly and even surpassed the rate of SCC. There are statistically significant differences among the carcinoma types during the sub-periods (P<0.05 and P<0.005), which confirm the assumption that there is a trend towards an increase of adenocarcinoma.

It appears that the increase of adenocarcinoma is due to multiple contributing factors. Further studies of longer duration are needed to help to elucidate the relative role of these factors. Pathological studies, the basis of lung cancer research, have a significant role regarding prevention and cure as well as etiological investigation of lung cancer. We adopted the WHO's 1981 criteria for lung cancer histological classification to classify the 1048 lung cancer cases. After discussing the etiology, we concluded that it also was necessary for us to observe the variance of lung cancer histological types over a long period. So, in this paper, more cases were observed over a long period and more data about lung cancer were obtained than in the former paper. 1 Materials and Method A total 1060 lung cancer specimens, including biopsy and surgically excised tissue, were collected in the First Affiliated Hospital of Guangzhou Medical College from 1978 to 1994. Based on the first five categories in the Histological Classification of Lung Malignant Epithelial Tumors, which was issued by WHO in 1981, 1048 cases were classified in the same way as a former paperl except for 12 cases (including a carcinoid tumor, malignant lymphoma and adenoid cystadenocarcinoma), which were not included in the statistical analysis. The period of 16 years from 1978 to 1994 was divided into 3 sub-periods, i.e., the first sub-period was - 2 -

from 1978 to 1984, the second from 1985 to 1990 and the third from 1990 to 1994. The data were analyzed by sub-period. Results In a total of 1048 cases there were 573 squamous cell carcinomas (54.68%), 340 adenocarcinomas (32.44%), 54 small cell carcinomas (5.15%) and 20 large cell carcinomas (1.91%). The remaining 61 cases were adenosquamous carcinomas (5.82$). The histological types and their rates during different sub-periods are shown in Table 1. Table 1. Histological types of 1048 lung cancer cases and their rates during different sub-periods Sub-Period/ Cell Type 1978-1984 1985-1990 1990-1994 Total Squamous 145 (68.72%) 312 (57.99%) 116 (38.8%) 573 Cell Carcinoma Small Cell 16 (7.58%) 25 (4.65%) 13 (4.34%) 54 Carcinoma Adeno- 41 (19.43%) 157 (29.18%) 142 (47.49%) 340 carcinoma Large Cell 9 (4.26%) 6 (1.12%) 5 (1.67%) 20 Carcinoma Adeno- 38 (7.06%) 23 (7.69%) 61 squamous Carcinoma ITotal 211 538 299 1048 - 3 -

The rates of squamous cell carcinoma and adenocarcinoma in the 1048 cases on above table are similar to those in a former paper.1 The rate of adenosquamous carcinoma, however, appears to have increased. The following is the graph of the data described above. 100 80 60 40 20 0 1978-1984 1985-1990 1990-1994 Squamous Cell Carcinoma Adenocarcinoma As shown above, during the last fifteen years the proportion of squamous cell carcinoma of the total lung cancers has been decreasing progressively. The rate of adenocarcinoma, however, has markedly increased. A statistically significant difference was observed (P<0.05 and P<0.005) in the incidence of the two types among the three time intervals. - 4 -

Discussion The rates of squamous cell carcinoma and adenocarcinoma in a total of 1048 lung carcinoma cases are similar to those described in a previous paper.C13 The incidence of squamous cell carcinoma declined while the incidence of adenocarcinoma increased significantly, which confirmed the hypothesis described in a paper.111 Epidemiological data showed that during the last two decades the incidence of lung cancer continued to increase; thus, as a consequence the rate of death also increased. Specifically, the incidence of lung adenocarcinoma has been rising significantly. More attention should have been paid to the epidemiological and etiological research concerning lung cancer. From a pathological point of view, we should focus on the relationship between histological types and environmental factors such as smoking as well as age and sex. From the point of view of the genesis of lung cancer, squamous cell carcinoma arises from the bronchial epithelium which has already undergone squamous metaplasia, where the epithelium has undergone repeatedly proliferation and destruction caused by chronic inflammation. This pathological development is considered to be a long process. Adenocarcinoma perhaps develops in shorter time than squamous cell carcinoma since adenocarcinoma can arise directly not only from the epithelium of the bronchial tree but also from the glands along the bronchial wall. Adenocarcinoma tends to occur in younger individuals. To classify more sub-types

would benefit multifactorial carcinogenesis research on lung cancer. Reference: 1. Li Lie Histological Classification and Aetiology Discussion of Lung Cancer in Guangzhou City. Published on the First International Academic Discussion of Pathology. Zhu Hai, China. June, 1988.