© 2005 Oxford University Press
IN THIS ISSUE |
IN THIS ISSUE
Market Share of Managed Care and Quality of CareIncreases in the market share of managed care are associated with decreases in expenditures in the fee-for-service sector, a phenomenon known as a "spillover effect." Because of concerns that lower expenditures result from reductions in necessary care, Keating et al. (p. 257) examined associations between increases in the market share of managed care and changes in the quality of care delivered to fee-for-service Medicare beneficiaries diagnosed with breast or colorectal cancer. The authors found that increases in the market share of managed care were not associated with rates of surveillance mammography after diagnosis, radiation after breast-conserving surgery, adjuvant chemotherapy for stage III colorectal cancer, or surveillance colonoscopy after treatment for colorectal cancer but were associated with increased rates of surveillance carcinoembryonic antigen testing for colorectal cancer. The authors conclude that concerns that increases in managed care would have large negative effects on the quality of cancer care appear to be unfounded.
In an editorial, Lipscomb (p. 242) discusses evidence that spillover effects can arise at various points along the cancer care continuum, including at the level of screening. He also discusses the kinds of future analyses that will be necessary to track variations in cancer care across populations and over time.
Hepatitis B Virus Genotype and DNA Level in HCC
Chronic hepatitis B virus (HBV) infection is a cause of hepatocellular carcinoma (HCC). Yu et al. (p. 265) quantified HBV DNA levels (a measure of viral load) in plasma DNA samples from 4,841 Taiwanese men who carried HBV but had not been diagnosed with HCC, and determined the HBV genotypes for the 154 men who were diagnosed with HCC during 14 years of follow-up and 316 control subjects. They found that increasing HBV viral load and genotype C HBV were independently associated with an increased risk of HCC. Genotype C HBV was associated with increased viral load, and associations of HBV genotype and viral load with HCC risk were additive. The authors conclude that measurements of HBV load and genotype may help to define which male HBV carriers are at high risk for HCC.
In an editorial, Goedert (p. 245) provides a historical perspective on the link between HBV and HCC and discusses how HBV load and genotype may affect patient responses to or complications from medications that are currently used against chronic HBV infection. He notes that primary prevention of HCC by universal HBV vaccination is the most important approach to controlling this lethal infectious carcinogen.
Hypermethylated Genes and Cervical Cancer
DNA methylation changes are an early event in carcinogenesis and are often present in the precursor lesions of various cancers, including cervical cancer. Feng et al. (p. 273) examined whether DNA methylation changes of 20 genes might be used as markers of cervical intraepithelial neoplasia (CIN) and invasive cervical cancer among a Senegalese population. The authors found that the frequency of hypermethylation for at least one of three genes (DAPK1, RARB, or TWIST1) increased with increasing severity of neoplasia but was rare in samples with CIN-1 or less. The authors estimated that, among Senegalese women presenting to community-based clinics, detection of the DAPK1, RARB, or TWIST1 hypermethylated gene would reveal histologically confirmed CIN-3 or worse with a sensitivity of 60% and a specificity of 95%, which are comparable to values achievable with thin-layer Pap smear screening. The authors conclude that methylation analysis is a potential diagnostic tool for cervical cancer screening.
Coffee, Tea, and Caffeine and Colorectal Cancer Incidence
Frequent coffee consumption has been associated with a reduced risk of colorectal cancer in a number of case–control studies. Cohort studies have not revealed such an association but were limited in size. Michels et al. (p. 282) used data from two large prospective cohorts to examine the association between consumption of coffee, tea, and caffeine and the incidence of colorectal cancer. They found that consumption of caffeinated coffee or tea, or caffeine intake was not associated with the incidence of colon or rectal cancer in either cohort, but that cohort members who regularly consumed two or more cups of decaffeinated coffee per day had a 52% lower incidence of rectal cancer than those who never consumed decaffeinated coffee (crude incidence rates of 12 cases per 100,000 person-years of follow-up and 19 cases per 100,000 person-years, respectively).
Liver Cancer Risk and Coffee Drinking in Japan
Although results from animal studies suggest an association between drinking coffee and reduced risk of liver cancer, no evidence for this association exists in a high-risk human population. Therefore, Inoue et al. (p. 293) conducted a prospective study using 334 hepatocellular carcinoma patients identified from a large, prospective study in Japan. Those who drank coffee on a daily or almost daily basis had a lower risk of developing liver cancer (214.6 cases per 100,000 people over 10 years) than those who almost never drank coffee (547.2 cases per 100,000 people over 10 years), and risk decreased with the amount of coffee consumed. Similar associations were observed in hepatitis B and C virus-positive patients and to those with no past history of chronic liver disease. The authors conclude that in the Japanese population, habitual coffee drinking may be associated with a reduced risk of hepatocellular carcinoma.
Tissue Zinc Concentrations and Esophageal Cancer Risk
Animal studies have found an association between zinc deficiency and esophageal cancer risk. Because the mechanisms by which zinc deficiency increases the incidence of esophageal carcinogenesis are thought to occur locally in the target tissue, Abnet et al. (p. 301) measured zinc, copper, iron, nickel, and sulfur concentrations in tissue sections to determine the association between incident esophageal squamous cell carcinoma and baseline element concentrations. The authors found that the risk of developing esophageal cancer was much lower for subjects with higher concentrations of zinc in esophageal tissue than for those with lower concentrations. The authors also found evidence that individuals with higher concentrations of sulfur had a lower risk of esophageal cancer than individuals with lower concentrations, but there was no association between copper, iron, or nickel concentrations and risk of esophageal cancer.
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