Early lung cancer detection and localization

Early diagnosis of lung cancer

Recent advances in computer-assisted image analysis, tumor biology, PCR-based assays, fluorescence bronchoscopy, spiral CT, endobronchial treatment modalities, and chemoprevention make it possible to re-examine the strategy of early detection in the comprehensive management of lung cancer.

Non-small cell lung cancer. Part I: Biology, diagnosis, and staging

Squamous, large cell, and adenocarcinoma, collectively termed non-small cell lung cancer (NSCLC), are diagnosed in approximately 75% of patients with lung cancer in the United States. The treatment of these three tumor cell types is approached in virtually identical fashion because, in contrast to small cell carcinoma of the lung, NSCLC more frequently presents with localized disease at the time of diagnosis and is thus more often amenable to surgical resection but less frequently responds to chemotherapy and irradiation. Cigarette smoking is etiologically related to the development of NSCLC in the great majority of cases. Genetic mutations in dominant oncogenes such as K-ras, loss of genetic material on chromosomes 3p, 11p, and 17p, and deletions or mutations in tumor suppressor genes such as rb and p53 have been documented in NSCLC tumors and tumor cell lines. NSCLC is diagnosed because of symptoms related to the primary tumor or regional or distant metastases, as an incidental finding on chest radiograph, or rarely because of a paraneoplastic syndrome such as hypercalcemia or hypertrophic pulmonary osteoarthropathy. Screening smokers with periodic chest radiographs and sputum cytologic examination has not been shown to reduce mortality. The diagnosis of NSCLC is usually established by fiberoptic bronchoscopy or percutaneous fine-needle aspiration, by biopsy of a regional or distant metastatic site, or at the time of thoracotomy. Pathologically, NSCLC arises in a setting of bronchial mucosal metaplasia and dysplasia that progressively increase over time. Squamous carcinoma more often presents as a central endobronchial lesion, while large cell and adenocarcinoma have a tendency to arise in the lung periphery and invade the pleura. Once the diagnosis is made, the extent of tumor dissemination is determined. Since most NSCLC patients who survive 5 years or longer have undergone surgical resection of their cancers, the focus of the staging process is to determine whether the patient is a candidate for thoracotomy with curative intent. The dominant prognostic factors in NSCLC are extent of tumor dissemination, ambulatory or performance status, and degree of weight loss. Stages I and II NSCLC, which are confined within the pleural reflection, are managed by surgical resection whenever possible, with approximate 5-year survival of 45% and 25%, respectively. Patients with stage IIIa cancers, in which the primary tumor has extended through the pleura or metastasized to ipsilateral or subcarinal lymph nodes, can occasionally be surgically resected but are often managed with definitive thoracic irradiation and have 5-year survival of approximately 15%.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytologic diagnosis of radiographically occult squamous call carcinoma of the lung

From 1978-1980, 20 patients with radiographically occult squamous cell carcinoma of the lung were admitted to Toronto General Hospital. Among them, five had in situ carcinoma, three had microinvasive carcinoma, and 12 early invasive. All cases were first diagnosed by cytologic examinations of sputum, localized by bronchoscopy, and had been verified histologically. It appears that a cytologic diagnosis of in situ squamous cell carcinoma of the lung could not be established on the basis of a single abnormal squamous cell or an occasional group of abnormal cells, but could be reached by putting together all the cytologic findings observed in the preparations. The criteria for the cytologic diagnosis are elucidated. Cytomorphologically there was no difference between microinvasive and advanced invasive carcinoma. However, in a patient with known localized in situ carcinoma and previous persistent cytologic findings of the same from that particular site, the finding of frankly malignant cells from the same site in the follow-up bronchoscopic examination was almost definitely an indication of microinvasive carcinoma, which usually showed evidence of both in situ and invasive carcinoma in the bronchial brushing specimens. None of the three microinvasive carcinoma cases had positive lymph nodes, but four of the 12 patients with early invasive carcinoma had metastases to the nodes at the time of surgery. Hence, the best time to effectively treat the invasive squamous cell carcinoma of the lung is at the microinvasive stage when the disease is considered curable.

Results of Mayo lung project: an interim report

Screening for lung cancer by chest roentgenography and sputum cytology can be conducted by mail. Detection, localization, and treatment of early presymptomatic lesions are possible. The initial prevalence of lung cancer in men older than age 45 years who were heavy smokers was almost 1%. Rescreening at 4-monthly intervals detected 4.7 new cases of lung cancer per 1,000 subjects per year. Three times as many postsurgical stage I lesions were detected in the screened group as in the control group. Although survival seems to have been improved by screening, mortality from lung cancer is not yet significantly different in the 4-monthly surveillance and control groups. Longer follow-up is necessary for determination of the ultimate usefulness of screening.

Sputum cytologic diagnosis of upper respiratory tract cancer. Second report

Screening for cancer is a popular issue for debate because few, if any, evaluations of the screening process have been conducted on a long-term prospective basis with use of concomitant, unscreened controls. We have found that screening of high-risk persons for presymptomatic lung cancer will identify patients with cancer in the upper and lower respiratory passages. Randomly selected patients enrolled in the Mayo Lung Project have undergone sputum cytologic and chest roentgenographic screening at four-month intervals and were compared with randomly selected matched control subjects who were not intensively screened. The search for upper airway tumors in the head and neck region was instigated by abnormal findings on sputum cytology in 12 screened patients. In the same period, 12 other screened patients with abnormal results of sputum cytology were found to have roentgenographically "occult" lung cancer. This finding emphasized the importance of the otorhinolaryngologic examination in screening programs for airway cancer. It is also important to emphasize that sputum-negative patients may have obvious, symptomatic tumors of the upper aerodigestive tract that can be easily diagnosed by those who are skilled in examining this area. Contrary to our expectation, there is no definitive evidence that screening has reduced mortality from either upper or lower airway cancer.

Sputum cytologic diagnosis of upper respiratory tract cancer

Sputum cytologic testing has been applied in the screening of high-risk individuals for presymptomatic lung cancer. This same screening procedure sometimes identifies patients with upper respiratory tract cancers and thereby may permit earlier treatment. Patients enrolled in the Mayo Lung Project undergo sputum cytologic and chest roentgenographic screening at four-month intervals and are compared with matched controls who are not intensively screened. Experience to date indicates an incidence rate of approximately 1 per 1,000 per year of cancer in the upper respiratory and alimentary passages among males more than 45 years old who are heavy cigarette smokers. This compares with a rate of approximately 4 per 1,000 per year of lung cancer. Recognition of early cancer of the upper respiratory tract is an additional benefit of screening for lung cancer. Since cigarette smoking represents an etiologic agent common to both upper and lower respiratory tract cancers, tumors should be searched for in both sites in this high-risk population.