The experience with pulmonary disease caused by Mycobacterium avium complex (MAC-PD) was examined over a 12-yr period in a nonreferral setting. The 29 patients with the disease constituted 30% of all pleuropulmonary mycobacterioses. The mean annual incidence rate was 1/100,000. Sixty-two percent of patients were female, the majority of whom had no discernible preexisting pulmonary disorder to account for their susceptibility. A short- and long-term favorable response to therapy was observed in more than 90% of the 16 patients treated with intent to cure. Suggested as plausible explanations for the favorable response rate compared with previous studies originating in referral settings were: absence of adverse selection as shown by a smaller proportion of patients with far-advanced cavitary disease or with previous treatment failure, and a larger proportion of female patients. A previously unreported pattern of MAC-PD was observed: disease limited to the lingula or middle lobe occurred in 21% of the patients, all female. A rarely identified pattern, primary disease in a 3-yr-old exposed to pet birds, is reported.
Background: The magnitude of overdiagnosis is a critical and unresolved issue in lung cancer (LC) screening: (1) its contribution to the increase in survival constitutes specious evidence of benefit; (2) overdiagnosed individuals who undergo resection will experience a reduction in life expectancy, partially or completely offsetting the benefit received by others in whom earlier intervention proves curative. Method: Critical analysis of studies in opposition and support of the view that LC screening imposes a substantial burden of overdiagnosis.Results: Approximately 25%, possibly more, of radiographically (chest x ray) diagnosed LC appears to be overdiagnosed. Based on the observed tumour volume doubling time of low dose CT identified small malignant pulmonary nodules, CT will markedly augment lead time, increasing exposure to competing lethal morbidities, thereby increasing overdiagnosis. Conclusion: To reduce all-cause mortality, CT screening will need to reduce LC mortality by an amount that exceeds the increase in mortality attributable to surgery and loss of pulmonary reserve in persons who are overdiagnosed or pathologically understaged (ie, with occult micrometastases). Presently, there is no evidence that CT screening will achieve any reduction in LC mortality.Because of its frequency and lethality, identifiable high risk population and absence of effective nonsurgical treatment, lung cancer (LC) is an ideal screening candidate. However, because controlled trials combining radiographic (chest x ray (CXR)) and cytological screening achieved no reduction in mortality, screening is not recommended by recognised professional societies (summarised by Bach and colleagues 1 ). The development of low dose, spiral CT screening has generated a resurgence of interest because it is about fourfold more sensitive than CXR at identifying small peripheral LC, and because approximately 80% of CT identified LC are stage IA, which have a highly favourable surgical prognosis 2 : 5 year LC survival of surgically staged IA LC is about 70% while overall 5 year LC survival is approximately 15%.
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