Physical activity and endometrial cancer risk, a systematic review of current evidence.

OBJECTIVE: To assess the epidemiologic evidence for the association between physical activity and endometrial cancer risk, taking into account the methodologic quality of each study. DESIGN: Systematic review, best evidence synthesis. DATA SOURCES: Studies were identified through a systematic review of literature available on PubMed through December 2006. REVIEW METHODS: We included cohort and case-control studies that assessed total and/or leisure time and/or occupational activities in relation to the incidence of endometrial cancer. The methodologic quality of the studies was assessed with a comprehensive scoring system. RESULTS: The included cohort (n = 7) and case-control (n = 13) studies consistently show that physical activity is associated with a decreased risk of endometrial cancer. The best evidence synthesis showed that the majority (80%) of 10 high-quality studies found risk reductions of >20%. Pooling of seven high-quality cohort studies that measured total, leisure time, or occupational activity showed a significantly decreased risk of endometrial cancer (summary estimate: OR, 0.77; 95% CI, 0.70-0.85) for the most active women. Case control studies with relatively unfavorable quality scores reported divergent risk estimates, between 2-fold decreased and 2-fold increased risk. Effect modification by body mass index or menopausal status was not consistently observed. Evidence for an effect of physical activity during childhood or adolescence was limited. CONCLUSIONS: Physical activity seems to be associated with a reduction in the risk of endometrial cancer, which is independent of body weight. Further studies, preferably prospective cohort studies, are needed to determine the magnitude of the risk reduction and to assess which aspects of physical activity contribute most strongly to the reduced risk and in which period of life physical activity is most effective.

Physical activity and breast cancer: a systematic review.

BACKGROUND: Many epidemiologic studies have found an association between physical activity and breast cancer risk, although this has not been a consistent finding. METHODS: Studies were identified through a systematic review of literature available on PubMed through February 2006. We included all cohort and case-control studies that assessed total or leisure time activities in relation to occurrence or mortality of breast cancer. The fully adjusted risk estimates and 95% confidence intervals for the highest versus lowest level of activity were documented for each study as well as evidence for a dose-response relationship. Methodologic quality was also assessed. Due to statistical and methodologic heterogeneity among studies, we did not carry out statistical pooling. To draw conclusions, we performed a best-evidence synthesis taking study quality into account. RESULTS: Nineteen cohort studies and 29 case-control studies were evaluated. There was strong evidence for an inverse association between physical activity and postmenopausal breast cancer with risk reductions ranging from 20% to 80%. For premenopausal breast cancer, however, the evidence was much weaker. For pre- and postmenopausal breast cancer combined, physical activity was associated with a modest (15-20%) decreased risk. Evidence for a dose-response relationship was observed in approximately half of the higher-quality studies that reported a decreased risk. A trend analysis indicated a 6% (95% confidence interval = 3% to 8%) decrease in breast cancer risk for each additional hour of physical activity per week assuming that the level of activity would be sustained. CONCLUSIONS: There is evidence for an inverse association between physical activity and breast cancer risk. The evidence is stronger for postmenopausal breast cancer than for premenopausal breast cancer.

Cancer mortality rates among first and second generation migrants in the Netherlands: Convergence toward the rates of the native Dutch population.

This study investigates the difference in cancer mortality rates between migrant groups and the native Dutch population, and determines the extent of convergence of cancer mortality rates according to migrants' generation, age at migration and duration of residence. Data were obtained from the national cause of death and population registries in the period 1995-2000. We used Poisson regression to compare the cancer mortality rates of migrants originating from Turkey, Morocco, Surinam, Netherlands Antilles and Aruba to the rates for the native Dutch. All-cancer mortality among all migrant groups combined was significantly lower when compared to that of the native Dutch population (RR = 0.55, CI: 0.52-0.58). For a large number of cancers, migrants had more than 50% lower risk of death, while elevated risks were found for stomach and liver cancers. Mortality rates for all cancers combined were higher among second generation migrants, among those with younger age at migration, and those with longer duration of residence. This effect was particularly pronounced in lung cancer and colorectal cancer. For most cancers, mortality among second generation migrants remained lower compared to the native Dutch population. Surinamese migrants showed the most consistent pattern of convergence of cancer mortality. The generally low cancer mortality rates among migrants showed some degree of convergence but did not yet reach the levels of the native Dutch population. This convergence implies that current levels of cancer mortality among migrants will gradually increase in future years if no specific preventive measurements are taken.

A study into methodology and application of quantification of tumour vasculature in rectal cancer.

The application of new surgical techniques in combination with preoperative radiotherapy has minimised the risk of local recurrence in rectal cancer. However, distant metastasis is still a serious problem after seemingly curative resection in patients with rectal cancer. The present study aimed to evaluate the methodology for quantification and the characteristics of the tumour vasculature in relation to the development of metastasis in patients with rectal cancer. From a large multicentre trial, 88 patients were selected, ensuring a relatively high percentage of metastasis. This selection facilitates the study of tumour vasculature characteristics in relation to metastasis. Vessel number, perimeter and area were assessed at both the invasive front and intratumoural area. Hot-spot and random selections were performed simultaneously. The median of each vessel parameter in the study population was used to separate patients into a low- and high-vessel group. Differences in development of distant metastasis were studied between low- and high-vessel groups. The data of the present study show that only vascular perimeter randomly assessed at the invasive front was associated with distant metastasis. Patients with a high score had a lower distant metastasis rate than patients with a low score (37% and 62%, respectively). High-vessel perimeter was independent of tumor node metastasis staging, but was associated with an increased presence of immune cells, comprising T cells, mast cells, eosinophils and neutrophils. This methodological study on the biological relevance of various vessel characteristics showed that a large vascular endothelial surface, as reflected by a high perimeter, was the only vessel characteristic indicative of improved patient outcome. The underlying principle for this association may be the improved immune response.

Effect of blood sample handling and reverse transcriptase-polymerase chain reaction assay sensitivity on detection of CK20 expression in healthy donor blood.

Data concerning the specificity of cytokeratin 20 (CK20) as a reverse transcriptase-polymerase chain reaction analysis (RT-PCR) marker to detect disseminated tumor cells in blood are conflicting. Underlying causes for these discrepancies need to be determined to clarify the significance of CK20 detection. Because differences in RT-PCR assays and blood sample handling may be important, their influence on CK20 detection was studied. Using a series of healthy donor blood samples spiked with colon tumor cells, the authors compared the sensitivities of two conventional PCRs with different primer sets and a quantitative LightCycler PCR (Roche Diagnostics GmbH, Penzberg, Germany). Additionally, the influence of sample collection and preparation on assay specificity was studied by examining CK20 expression in the mononuclear cell fraction (MNC) of the first and the second aliquot of blood drawn from healthy donors and in the granulocyte cell fraction. At the concentration of one spiked tumor cell/mL blood, the CK20 detection frequency varied from 17% and 67% for the conventional to 78% for the LightCycler PCR. In the unspiked samples, CK20 was detected in 0% and 8% of the conventional and in 11% of the LightCycler PCR tests. Quantitative analysis revealed that CK20 was expressed at a high level in the granulocyte samples. The results demonstrate that differences in assay sensitivity and sample handling influence CK20 detection in blood.