There has been conflicting evidence concerning the possible association between tuberculosis (TB) and subsequent risk of lung cancer. To investigate whether currently published epidemiological studies can clarify this association, we performed a systematic review of 37 case-control and 4 cohort studies (published between January 1966 and January 2009) and a meta-analysis of risk estimates, with particular attention to the role of smoking, passive smoking and the timing of diagnosis of TB on this relationship. Data for the review show a significantly increased lung cancer risk associated with preexisting TB. Importantly, the association was not due to confounding by the effects of tobacco use (RR 5 1.8, 95% confidence interval (CI) 5 1.4-2.2, among never smoking individuals), lifetime environmental tobacco smoke exposure (RR 5 2.9, 95%CI 5 1.6-5.3, after controlling) or the timing of diagnosis of TB (the increased lung cancer risk remained 2-fold elevated for more than 20 years after TB diagnosis). Interestingly, the association was significant with adenocarcinoma (RR 5 1.6, 95%CI 5 1.2-2.1), but no significant associations with squamous and small cell type of lung cancer were observed. Although no causal mechanism has been demonstrated for such an association, present study supports a direct relation between TB and lung cancer, especially adenocarcinomas. ' UICCKey words: systematic review; tuberculosis; meta-analysis; lung cancer Lung cancer as the most common cancer in the world represents a major public health problem. Worldwide it accounts for approximately 1.2 million cancer-related deaths each year.1 In men it is the largest cause of mortality, and in women it is the third largest cause, just after breast and intestinal cancer, but before cervical cancer.2-4 Good prevention and early detection of breast and cervical cancer mean that lung cancer will be the leading cause of mortality in women worldwide, too.5 Tuberculosis (TB) is another major cause of morbidity and mortality, especially in developing countries. Worldwide, approximately one third of people are infected with Mycobacterium tuberculosis, the causative microorganism, and with aging or weakening of the immune system, this infection can reactivate, leading to severe and prolonged pneumonia, pulmonary scarring and wasting.6 It has been well documented that lung inflammation and fibrosis from TB could induce genetic damage, which may increase the risk of lung cancer. [7][8][9] Along these lines, a number of retrospective case-control/prospective cohort studies have reported that subjects with a history of preexisting TB experience excess risk of lung cancer. However, the evidence has been inconsistent, and there has also been uncertainty about the temporal relationship between previous TB and lung cancer and possible residual confounding by cigarette smoking, passive smoking and the timing of diagnosis of TB. The determination of whether or not there is such an association has potential importance for managing TB, for screening of lung cancer an...
This systematic review suggests that specific heart failure-targeted interventions significantly decrease hospital readmissions but do not affect mortality rates.
for the Evidence-Based Medicine Working Group CLINICAL SCENARIO You are a general internist who is asked to see a 65-year-old man with controlled hypertension and a 6-month history of atrial fibrillation resistant to cardioversion. Although he has no evidence for valvular or coronary heart disease, the family physician who referred him to you wants your advice on whether the benefits of long-term anticoagulants (to reduce the risk of embolic stroke) outweigh their risks (of hemorrhage from anticoagulant therapy). The patient shares these concerns and doesn't want to receive a treatment that would do more harm than good. You know that there have been randomized trials of warfarin for nonvalvular atrial fibrillation and decide that you'd better review one of them.
for the Evidence-Based Medicine Working Group CLINICAL SCENARIO You are working as an internal medicine resident in a rheumatology rotation and are seeing a 19-year-old woman who has had systemic lupus erythematosus diagnosed on the basis of a characteristic skin rash, arthritis, and renal disease. A renal biopsy has shown diffuse proliferative nephritis. A year ago her creatinine level was 140 \g=m\mol/L, 6 months ago it was 180 \g=m\mol/L, and in a blood sample taken a week before this clinic visit, 220 \g=m\mol/L. Over the last year she has been taking prednisone, and over the last 6 months, cyclophosphamide, both in appropriate doses.
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