One of the greatest challenges facing human geneticists is the identification and characterization of susceptibility genes for common complex multifactorial human diseases. This challenge is partly due to the limitations of parametric-statistical methods for detection of gene effects that are dependent solely or partially on interactions with other genes and with environmental exposures. We introduce multifactor-dimensionality reduction (MDR) as a method for reducing the dimensionality of multilocus information, to improve the identification of polymorphism combinations associated with disease risk. The MDR method is nonparametric (i.e., no hypothesis about the value of a statistical parameter is made), is model-free (i.e., it assumes no particular inheritance model), and is directly applicable to case-control and discordant-sib-pair studies. Using simulated case-control data, we demonstrate that MDR has reasonable power to identify interactions among two or more loci in relatively small samples. When it was applied to a sporadic breast cancer case-control data set, in the absence of any statistically significant independent main effects, MDR identified a statistically significant high-order interaction among four polymorphisms from three different estrogen-metabolism genes. To our knowledge, this is the first report of a four-locus interaction associated with a common complex multifactorial disease.

To assess the importance of various risk factors for breast cancer in women with benign proliferative breast lesions, we reevaluated 10,366 consecutive breast biopsies performed in women who had presented at three Nashville hospitals. The median duration of follow-up was 17 years for 3303 women, 1925 of whom had proliferative disease. This sample contained 84.4 per cent of the patients originally selected for follow-up. Women having proliferative disease without atypical hyperplasia had a risk of cancer that was 1.9 times the risk in women with nonproliferative lesions (95 per cent confidence interval, 1.2 to 2.9). The risk in women with atypical hyperplasia (atypia) was 5.3 times that in women with nonproliferative lesions (95 per cent confidence interval, 3.1 to 8.8). A family history of breast cancer had little effect on the risk in women with nonproliferative lesions. However, the risk in women with atypia and a family history of breast cancer was 11 times that in women who had nonproliferative lesions without a family history (95 per cent confidence interval, 5.5 to 24). Calcification elevated the cancer risk in patients with proliferative disease. Although cysts alone did not substantially elevate the risk, women with both cysts and a family history of breast cancer had a risk 2.7 times higher than that for women without either of these risk factors (95 per cent confidence interval, 1.5 to 4.6). This study demonstrates that the majority of women (70 per cent) who undergo breast biopsy for benign disease are not at increased risk of cancer. However, patients with a clinically meaningful elevation in cancer risk can be identified on the basis of atypical hyperplasia and a family history of breast cancer.

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In patients with sepsis, treatment with ibuprofen reduces levels of prostacyclin and thromboxane and decreases fever, tachycardia, oxygen consumption, and lactic acidosis, but it does not prevent the development of shock or the acute respiratory distress syndrome and does not improve survival.

Fibroadenoma is a long-term risk factor for breast cancer. The risk is increased in women with complex fibroadenomas, proliferative disease, or a family history of breast cancer.

BACKGROUNDOpportunities to study the natural history of ductal carcinoma in situ (DCIS) are rare. A few studies of incompletely excised lesions in the premammographic era now recognized as DCIS have provided critical insights into its proclivity for local recurrence in the original site. At the time the biopsies in the current study were originally examined, small DCIS was not diagnosed and, by default, these women were treated by biopsy only.METHODSThe authors report the latest results from a follow‐up study, which was published originally in 1982, of 28 women with low‐grade DCIS who were treated by biopsy only. These women were from a large, prospectively identified, completely characterized cohort.RESULTSEleven of 28 women developed invasive breast carcinoma (IBC), all in the same breast and quadrant from which their low‐grade DCIS biopsy was taken. Seven IBCs were diagnosed within 10 years of the DCIS biopsy, 1 was diagnosed within 12 years of the DCIS biopsy, and the remaining 3 IBCs were diagnosed over 23–42 years. Five of these women, including 1 woman who developed IBC 29 years after her DCIS biopsy, developed distant metastasis, which resulted in death 1–7 years after the diagnosis of IBC.CONCLUSIONSThe natural history of low‐grade DCIS can extend greater than 4 decades, with IBC developing at the same site as the previous DCIS in the majority of women. This natural history differs markedly from that of patients with high‐grade DCIS and from the outcome of patients with any completely delimited DCIS excised to negative margins. Cancer 2005. © 2005 American Cancer Society.