Meta_Analysis在肿瘤循证医学中的应用_英文(4)

Chin J Clin Oncol (2008) 5: 1~9dential radon is a cause of lung cancer in the general population. The estimated risks at 0, 100, and 400 Bq/m3, relative to life-long nonsmokers, with no radon exposure, were 1.0, 1.2, and 1.6 for life-long nonsmokers, and 25.8, 29.9, and 42.3 for continuing smokers of 15~24 cigarettes/day. Taylor et al.[21] analyzed 43 primary studies from 1981 to the end of 1999. The abundance of evidence clearly indicated that non-smokers exposed to envi-ronmental tobacco smoke (ETS) are at increased risk for lung cancer. The pooled RR for never-smoking women exposed to ETS from spouses, compared with unexposed never-smoking women was 1.29 (95% CI=1.17~1.43).

Screeningchemotherapy and is currently the best estimate of the effectiveness of this therapy. Whether particular types of patients may benefit more or less from preopera-tive chemotherapy is unknown. A meta-analysis of phase III randomized trials as to whether chemotherapeutic combinations for advanced non-small cell lung cancer should use a platinum-based protocol, was made by Pujol et al.[27] A platinum-based doublet induced a statically sig-nificant reduction in the risk of death when compared with non-platinum chemotherapy without inducing an unacceptable increase in toxicity. Evidence-Based Oncology for Colon Cancer

EtiologyMany studies have examined different screening strategies for lung cancer. Through meta-analysis, Manser et al.[22] concluded that the current evidence does not support screening for lung cancer with chest radiography or sputum cytological examination. They suggested that frequent chest radiography might be harmful. Diederich et al.[23] reported that preliminary studies of low-dose CT in heavy smokers had demonstrated a high proportion of asymptomatic, early, resectable cancers with good survival, but some bias existed and there were no evidence of mortality reduction. Gen-eral recommendations to screen individuals at risk for lung cancer with low-dose CT should be made.

Therapy Based on 19 trials employing meta-analysis, Baggstrom et al.[24] concluded that third-generation chemotherapy agents (paclitaxel, docetaxel, gem-citabine, vinorelbine, and irinotecan) have achieved a significant advance in the treatment of non-small cell lung cancer (NSCLC) (12% survival difference versus second-generation (2G) platinum-based regi-mens). Pijls-Johannesma et al.[25] conducted a systematic review, and meta-analysis of randomized controlled trials on the timing of chest radiotherapy in patients with limited stage small cell lung cancer (LS-SCLC). When platinum-based chemotherapy concurrently with chest radiotherapy is used, the 2- and 5-year sur-vival rates of patients with LS-SCLC may be in favor of early chest radiotherapy, with a significant differ-ence if the overall treatment time of chest radiation is less than 30 days. Burdett et al.[26] investigated 12 eligible randomized controlled trials to look at outcome of chemotherapy and surgery versus surgery alone in NSCLC. This analysis showed a significant benefit of preoperative The association between dietary fruits/vegetables and cancer have been investigated in many studies. In a pooled analysis of 14 cohort studies, Koushik et al.[28] concluded that dietary fruit and vegetables were not strongly associated with colon-cancer risk overall, but may be associated with a lower risk of distal colon cancer (RR= 0.74, 95% CI=0.57~0.95, P=0.02). Gorham et al.[29] reported that the evidence to date suggests that daily intake of 1,000~2,000 IU/day of vitamin D could reduce the incidence of colorectal cancer with minimal risk (OR=0.49, P<0.0001, 95% CI=0.35~0.68). Larsson and Wolk[30] analyzed the pooled risk of meat consumption for colon cancer and identified 15 prospective studies on red meat (involving 7,367 cases) and 14 prospective studies on processed meat consumption (7,903 cases). The summary RRs of colorectal cancer for the highest vs. the lowest intake categories were 1.28 (95% CI=1.15~1.42) for red meat and 1.20 (95% CI=1.11~1.31) for processed meat. The meta-analysis supported the hypothesis that high consumption of red meat and of processed meat is associated with an increased risk of colorectal cancer. Larsson et al.[31] conducted a meta-analysis includ-ing 6 case-control and 9 cohort studies. The results support a relationship between diabetes and increased risk of colon and rectal cancer in both women and men (summary RR=1.26, 95% CI=1.05~1.50). Samad et al.[32] reported a meta-analysis including 19 cohort studies that showed considerable evidence that physical activity is associated with reduced risk of colon cancer in both males and females. ScreeningHeresbach et al.[33] reported that biennial fecal occult blood testing decreased colorectal cancer mortality by

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