Background. Bronchioloalveolar lung carcinoma (BAC) is a unique type of lung cancer with distinguishing pathologic, biologic, epidemiologic, demographic, and perhaps etiologic features. Methods. The authors investigated and analyzed all of the cases of pathologically confirmed BAC seen at our institution in the hope of discovering new or confirming known features of this disease. Results. When cases of BAC expressed as a percentage of total lung cancers were analyzed in successive 5‐year periods from 1955 to 1990, BAC rose from less than 5% to 24.0% (P <0.001). Much of the increase in BAC occurred in women, as evidenced by a male‐to‐female ratio that wavered around unity. The mean age of BAC adenocarcinoma patients was 59.2 ± 11.5 years, compared to 64.1 ± 13.5 years for non‐BAC adenocarcinoma (P <0.05). BAC also contrasted with other forms of lung cancer by exhibiting a relatively high incidence of multifocality (25% versus 5%) (P <0.001). There was an association between histologic subtype of BAC and pattern of pulmonic involvement. The mucinous subtype was more strongly associated with diffuse pulmonic involvement, and the sclerotic subtype was more strongly associated with multifocal involvement (P <0.001). Furthermore, BAC cases exhibited a 20% incidence of dedifferentiation into patterns of poorly differentiated adenocarcinoma, a feature that was more associated with the mucinous and sclerotic subtypes (P <0.05). Conclusions. The emergence of BAC as a prominent type of lung cancer should stimulate new basic laboratory and case‐control studies to elucidate further the natural history and etiology of this unique disease. Cancer 1994; 73:1163‐70.

The cigarette-smoking behavior of 840 patients with resected Stage I non-small cell lung cancer was analyzed prospectively for up to four years following diagnosis. Lung cancer patients were heavier smokers at diagnosis than other cancer patients and the general population. At one year, only 16.8 percent of the 317 current smokers at baseline, who were followed for two years or longer, continued to smoke, while 83.2 percent of patients either quit permanently (53.0 percent) or for some time period (30.2 percent). By two years, permanent cessation stabilized at over 40 percent; however, the prevalence of continuing smoking decreased through all periods of follow-up. Subjects who tried to quit or did quit permanently were more likely to be female and healthier than continuous smokers.

Over the past 7 years, 151 patients with malignant melanoma have been treated with BCG immunotherapy alone or as an adjunct to surgical therapy. Direct injection of metastatic melanoma lesions limited to skin resulted in 90% regression of injected lesions and 17% regression of uninjected lesions in immunocompetent patients. Approximately 25% of these patients remained free of disease for 1 to 6 years. Direct injections of BCG into nodules of patients with subcutaneous or visceral metastases resulted in a lower incidence of local control and no long term survivors. Attempts to improve the results of immunotherapy in these patients by palliative surgical resection of large metastatic lesions to lower tumor burden followed by BCG immunotherapy significantly improved the results although many patients still developed recurrent disease. Early results of a clinical trial combining BCG immunotherapy with regional lymphadenectomy in patients with melanoma metastatic to lymph nodes have been encouraging and promising. Further controlled clinical trials are necessary to elucidate the role of BCG in immunotherapy. However, since BCG is but one of a number of potential immunologic adjuvants, even more effective immunotherapy will be possible as further knowledge of the interactions of cellular and humoral immunity is acquired.

The high frequency of occult nodal metastases in non-small-cell lung cancer makes it clear that, without immunohistochemistry, disease is understaged in many patients. Therefore, it seems essential that immunohistochemical evaluation of the lymph nodes be undertaken in clinical trials.