Breast cancer is a morphologically and clinically heterogeneous disease; however, it is less clear how risk factors relate to tumour features. We evaluated risk factors by tumour characteristics (histopathologic type, grade, size, and nodal status) in a populationbased case -control of 2386 breast cancers and 2502 controls in Poland. Use of a novel extension of the polytomous logistic regression permitted simultaneous modelling of multiple tumour characteristics. Late age at first full-term birth was associated with increased risk of large (42 cm) tumours (odds ratios (95% confidence intervals) 1.19 (1.07 -1.33) for a 5-year increase in age), but not smaller tumours (P for heterogeneity adjusting for other tumour features (P het ) ¼ 0.007). On the other hand, multiparity was associated with reduced risk for small tumours (0.76 (0.68 -0.86) per additional birth; P het ¼ 0.004). Consideration of all tumour characteristics simultaneously revealed that current or recent use of combined hormone replacement therapy was associated with risk of small (2.29 (1.66 -3.15)) and grade 1 (3.36 (2.22 -5.08)) tumours (P het ¼ 0.05 for size and 0.0008 for grade 1 vs 3), rather than specific histopathologic types (P het ¼ 0.63 for ductal vs lobular). Finally, elevated body mass index was associated with larger tumour size among both pre-and postmenopausal women (P het ¼ 0.05 and 0.0001, respectively). None of these relationships were explained by hormone receptor status of the tumours. In conclusion, these data support distinctive risk factor relationships by tumour characteristics of prognostic relevance. These findings might be useful in developing targeted prevention efforts.
We conducted a population-based case -control study of reproductive factors in Warsaw and Ló qź, Poland, in 551 incident endometrial cancer cases and 1925 controls. The reproductive variable most strongly related to risk was multiparity, with subjects with three or more births having a 70% lower risk than the nulliparous women. The reduced risk was particularly strong below 55 years of age. Subjects with older ages at a first birth were also at reduced risk even after adjustment for number of births. Ages at last birth or intervals since last birth were not strongly related to risk. Spontaneous abortions were unrelated to risk, but induced abortions were associated with slight risk increases (odds ratios ¼ 1.28, 95% confidence intervals 0.8 -2.1 for 3 þ vs no abortions). The absence of effects on risk of later ages at, or short intervals since, a last birth fails to support the view that endometrial cancer is influenced by mechanical clearance of initiated cells. Alternative explanations for reproductive effects should be sought, including alterations in endogenous hormones.
Buccal cell samples are increasingly used in epidemiological studies as a source of genomic DNA. The accurate and precise quantitation of human DNA is critical for the optimal use of these samples. However, it is complicated by the presence of bacterial DNA and wide inter-individual variation in DNA concentration from buccal cell collections. The paper evaluated the use of ultraviolet light (UV) spectroscopy, Höechst (H33258) and PicoGreen as measures of total DNA, and real-time quantitative polymerase chain reaction (PCR) as a measure of human amplifiable DNA in buccal samples. Using serially diluted white blood cell DNA samples (at a concentration range of 300 to 0.5 ng microl-1), UV spectroscopy showed the largest bias, followed by Höechst, especially for low concentrations. PicoGreen and real-time PCR provided the most accurate and precise estimates across the range of concentrations evaluated, although an increase in bias with decreasing concentrations was observed. The ratio of real-time PCR to PicoGreen provided a reasonable estimate of the percentage of human DNA in samples containing known mixtures of human and bacterial DNA. Quantification of buccal DNA from samples collected in a breast cancer case-control study by PicoGreen and real-time PCR indicated that cytobrush and mouthwash DNA samples contain similar percentages of human amplifiable DNA. Real-time PCR is recommended for the quantification of buccal cell DNA in epidemiological studies since it provides precise estimates of human amplifiable DNA across the wide range of DNA concentrations commonly observed in buccal cell DNA samples.
BackgroundStructural variations such as copy number variants (CNV) influence the expression of different phenotypic traits. Algorithms to identify CNVs through SNP-array platforms are available. The ability to evaluate well-characterized CNVs such as GSTM1 (1p13.3) deletion provides an important opportunity to assess their performance.Results773 cases and 759 controls from the SBC/EPICURO Study were genotyped in the GSTM1 region using TaqMan, Multiplex Ligation-dependent Probe Amplification (MLPA), and Illumina Infinium 1 M SNP-array platforms. CNV callings provided by TaqMan and MLPA were highly concordant and replicated the association between GSTM1 and bladder cancer. This was not the case when CNVs were called using Illumina 1 M data through available algorithms since no deletion was detected across the study samples. In contrast, when the Log R Ratio (LRR) was used as a continuous measure for the 5 probes contained in this locus, we were able to detect their association with bladder cancer using simple regression models or more sophisticated methods such as the ones implemented in the CNVtools package.ConclusionsThis study highlights an important limitation in the CNV calling from SNP-array data in regions of common aberrations and suggests that there may be added advantage for using LRR as a continuous measure in association tests rather than relying on calling algorithms.
Previous studies suggested an association between atopic conditions and specific cancers. The results on the association with urothelial bladder cancer (UBC) are scarce and inconsistent. To evaluate the association between asthma and risk of UBC, we considered 936 cases and 1,022 controls from the Spanish Bladder Cancer/EPICURO Study (86% males, mean age 65.4 years), a multicenter and hospital-based case-control study conducted during 1998-2001. Participants were asked whether they had asthma and detailed information about occupational exposures, smoking habits, dietary factors, medical conditions and history of medication was collected through face-to-face questionnaires performed by trained interviewers. Since asthma and UBC might share risk factors, association between patients' characteristics and asthma was studied in UBC controls. Association between UBC and asthma was assessed using logistic regression unadjusted and adjusted for potential confounders. The complex interrelationships, direct and mediating effect of asthma on UBC, were appraised using counterfactual mediation models. Asthma was associated with a reduced risk of UBC (odds ratio (OR) = 0.54, 95% confidence interval (CI) 0.37, 0.79) after adjusting for a wide range of confounders. No mediating effect was identified. The reduced risk associated with asthma was restricted to patients with high-risk non-muscle invasive (OR = 0.25, 95%CI 0.10, 0.62) and muscle invasive UBC (OR = 0.32, 95%CI 0.15, 0.69). Our results support that asthma is associated with a decreased risk of UBC, especially among aggressive tumors. Further work on the relationship between asthma and other atopic conditions and cancer risk should shed light on the relationship between immune response mechanisms and bladder carcinogenesis.
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