Our data from a large group of women in a defined population indicate that screening mammography may miss tumors of lobular or mucinous histology and some rapidly proliferating, high-grade tumors.
Breast density largely explained decreased mammographic sensitivity at 12 months, whereas rapid tumor growth contributed to decreased mammographic sensitivity at 24 months. A 12-month versus a 24-month mammography screening interval may therefore reduce the adverse impact of faster growing tumors on mammographic sensitivity in younger women.
The only way to ensure that losses to follow-up have not biased study results is to keep all losses to an absolute minimum. Since more complete follow-up leads to the identification of additional disease events, the effort spent in locating cohort members also improves the precision as well as the validity of the study results. This presentation reviewed approaches for maximizing retention and minimizing loss to follow-up, including the importance of communicating the expectations of participation and collecting personal information at baseline, conducting frequent personal and mail contact, and providing incentives for participation. Response rates can be increased by repeated attempts to contact each cohort member using a range of approaches (e.g., telephone, mail, personal contacts) and by other procedures specific to mailed questionnaires, telephone interviews, or in-person visits. Lost participants can be traced by use of the NCOA system and contact with other local, state, and national sources. Finally, for those participants who are unable or unwilling to continue or who cannot be found, proxy interviews and/or use of the National Death Index may provide information on the outcomes of interest and vital status. Additional research evaluating the efficacy of the various approaches to retention and tracking is needed to help investigators learn how to best apply study resources to retain and keep track of the largest possible number of cohort members.
Current use of ERT is associated with lower specificity and lower sensitivity of screening mammography. Lower specificity could increase the cost of breast cancer screening, and lower sensitivity may decrease its effectiveness.
Background
Tobacco and alcohol are well-established risk factors for numerous cancers, yet their relationship to biliary tract cancers remains unclear.
Methods
We pooled data from 26 prospective studies to evaluate associations of cigarette smoking and alcohol consumption with biliary tract cancer risk. Study-specific hazard ratios (HRs) and 95% confidence intervals (CIs) for associations with smoking and alcohol consumption were calculated. Random-effects meta-analysis produced summary estimates. All statistical tests were two-sided.
Results
Over a period of 38 369 156 person-years of follow-up, 1391 gallbladder, 758 intrahepatic bile duct, 1208 extrahepatic bile duct, and 623 ampulla of Vater cancer cases were identified. Ever, former, and current smoking were associated with increased extrahepatic bile duct and ampulla of Vater cancers risk (eg, current vs never smokers HR = 1.69, 95% CI = 1.34 to 2.13 and 2.22, 95% CI = 1.69 to 2.92, respectively), with dose-response effects for smoking pack-years, duration, and intensity (all Ptrend < .01). Current smoking and smoking intensity were also associated with intrahepatic bile duct cancer (eg, >40 cigarettes per day vs never smokers HR = 2.15, 95 % CI = 1.15 to 4.00; Ptrend = .001). No convincing association was observed between smoking and gallbladder cancer. Alcohol consumption was only associated with intrahepatic bile duct cancer, with increased risk for individuals consuming five or more vs zero drinks per day (HR = 2.35, 95%CI = 1.46 to 3.78; Ptrend = .04). There was evidence of statistical heterogeneity among several cancer sites, particularly between gallbladder cancer and the other biliary tract cancers.
Conclusions
Smoking appears to increase the risk of developing all biliary tract cancers except gallbladder cancer. Alcohol may increase the risk of intrahepatic bile duct cancer. Findings highlight etiologic heterogeneity across the biliary tract.
These findings are consistent with previous evidence suggesting that scheduling a woman's mammogram during the follicular phase (first and second week) of her menstrual cycle instead of during the luteal phase (third and fourth week) may improve the accuracy of mammography for premenopausal women in their forties. Breast tissue is less radiographically dense in the follicular phase than in the luteal phase.
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