Lung cancer in Johannesburg

Mukansi, Murimisi Demmy
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Introduction: cancer remains the most common malignancy, with an estimated 1.04 million new cases each year worldwide, accounting for 12.8% of new cancer cases. Of these cases, 58% occur in the developing world. Lung cancer is the most common cancer among men, with an incidence of approximately 37.5 new cases per million. The incidence is lower in women, at 1.08 cases per million population. Lung cancer is the leading cause of morbidity and mortality in the world. There is evidence in the literature of racial and gender differences in the distribution of lung cancer. However data from South Africa is sparse. Aim: The primary objective of this study was to investigate whether differences existed in demographic and histological features of lung cancer when comparing black versus white patients with cancer of the lung in Johannesburg Methods: A retrospective case record review of 817 patients presenting to the pulmonology units of the three hospitals, between January 1992 and December 1998, was undertaken. Demographic, clinical, laboratory and histological features were captured and analyzed, using the GraphPad InStat 3.10 program for Windows. The histological cell types of lung cancer were characterized using the 1981 WHO classification. Results: A total of 817 patients with lung cancer were enrolled in the study. The age group of the total sample ranged between 26-92 years with a mean±SEM of 61.0±0.04 years. There were 574 (70.3%) male patients versus 222 (27.2%) female patients. The remaining 21 (2.6%) patients had no data recorded with respect to their gender. The racial stratification of these patients in decreasing order of frequency was whites 441 (54.0%), blacks 337 (41.3%), mixed race 24 (3.0%) and Indians 15 (1.8%). The study group consisted of the 778 black and white patients. The black patients were younger (mean ±SEM, 57.3±0.5years) than the white patients (mean ±SEM, 64.0±9.9) irrespective of gender (p <0.001). Overall 632 patients were smokers, either current or ex-smokers. The amount of cigarettes consumed was significantly higher in white patients compared to black patients (mean pack years for white patients was 52.7 ± 27.1 versus 21.7± 14.3 pack years for black patients (p <0.001)). This difference was irrespective of gender. The mode of diagnosis in the 778 lung cancer patients was bronchoscopy in the majority 479 (54.0%), followed by sputum cytology in 152 (18.3%) and fine needle aspiration in 105 (12.7%). Tissue biopsy was utilized to diagnose 23 (2.7%) of the lung cancers. In some cases more than a single modality of diagnosis was utilized. The radiological features of the 778 lung cancer patients varied. The majority had a mass on chest radiograph; a lung mass in 357 (46.5%) patients, a hilar mass in 166 (21.6%), and a mediastinal mass in 18 (0.3%) patients. Pleural effusions were found in 82 (10.7%), lung atelectasis in 78 (10.2%), an infiltrate in 29 (3.8%) and consolidation in 25 (3.3%). Histological cell types of lung cancer in the 778 patients consisted of the following, in descending order of frequency; squamous cell carcinoma in 341 (43.8%), adenocarcinoma in 167 (21.5%), small cell carcinoma in 129 (16.6%) and large cell carcinoma in 68 (8.7%) of the cases. Other histological cell types accounted for 73 (9.4%) of the patients. Small cell carcinoma was overall more common amongst white patients especially males and in black patients it was exclusively in females (p<0.0005). However the black female patients tended to have more small cell carcinoma (40 (45.5%)), compared to the white female patients who had more squamous cell carcinoma (54 (45.0%)) in the majority. There was a small proportion of patients considered to be operable with intent to cure -74 (9.5%). This was a poor operability rate compared to an expected operability rate of 15-20%. This rate was as distressing when divided along racial lines; 29 (8.6%) of black patients and 45 (10.2%) of white patients being considered operable. Discussion: The demographics of the study group were different. The black patients tended to be significantly younger and smoked less cigarettes compared to the white patients. There was a significantly greater number of male patients with lung cancer than female patients. This difference was irrespective of race. The ranked frequency of histological subtypes was similar in both race groups. However, the black female had more small cell carcinoma, compared to white females with a preponderance of squamous cell carcinoma. The operability of all lung cancer patients, irrespective of gender and race, was dismal at 9.5%, compared to the standard norm of 15-25% operability rate. This is worrying when one considers the fact that surgery is the means to a cure. It either suggests there is a delay in seeking medical care and/or the lack of medical resources to permit screening and early diagnosis of the malignancy. Conclusions: This study did not demonstrate any ranked frequency differences in histological cell type distribution between black and white patients. Squamous cell carcinoma was the most common histological cell type regardless of race. Small cell carcinoma was significantly more common among white patients, especially the males while among the black patients it was exclusively found in the females. Black patients with lung cancer tended to present at an earlier age. Black females were less likely to develop lung cancer when compared with the white females. The black patients smoked fewer cigarettes than the white patients irrespective of gender. The operability of our patients, in the study, was poor in all race groups.
Research report in partial fulfillment for the degree of MMed (Pulmonology), faculty of Health Sciences, University of the Witwatersrand
cancer, lung