Pregnancy Nausea/Vomiting May Indicate Lower Risk of Breast CancerJune 25, 2007BUFFALO, N.Y. -- It may not seem so at the time, but women who suffer through morning sickness during their pregnancies actually may be fortunate. Those women may have a 30 percent lower risk of developing breast cancer later in life than mothers-to-be who experience nine nausea-free months, a new study by epidemiologists at the University at Buffalo suggests. "Although the exact mechanism responsible for causing nausea and vomiting during pregnancy has yet to be pinpointed, it likely is a result of changing levels of ovarian and placental hormone production, which may include higher circulating levels of a hormone called human chorionic gonadotropin," said David Jaworowicz, Jr., first author on the study.
"In vitro studies have shown that this hormone possesses several activities that have potential protective effects against cancer cells," said Jaworowicz, a doctoral candidate in the Department of Social Preventive Medicine in UB's School of Public Health and Health Professions. Jaworowicz's research, which was presented today at the Society for Epidemiologic Research's annual meeting in Boston, Mass., found no association of other pregnancy-related medical conditions -- pregnancy-induced hypertension, preeclampsia, gestational diabetes or weight gain -- and breast-cancer risk. The study was based on data from participants in the Western New York Exposure and Breast Cancer Study, a population-based case-control study of breast cancer conducted in women 35-79 from two Western New York counties between 1996 and 2001. The analysis compared extensive data on pregnancy-related conditions from 1,001 women with primary breast cancer and 1,917 women without breast cancer matched to cases by age and race who served as controls. "Pregnancy is a time when the breast undergoes a variety of cellular and anatomical changes," said Jaworowicz. "During this period, the breast tissue is exposed to varying levels of a number of hormones, which may affect the physiology of the breast. "We were interested in the association between pregnancy-related events and characteristics, including pregnancy-induced hypertension, preeclampsia/eclampsia, gestational diabetes, high weight gain during pregnancy, and nausea and vomiting, because these markers may serve as proxies for underlying hormonal changes and altered hormone levels in blood and tissue." Jaworowicz noted that the presence or absence of these pregnancy-related conditions may indicate a different course or extent of hormone-regulated breast tissue proliferation and differentiation during pregnancy, but also may indicate distinct hormonal profiles that persist following pregnancy. Although pregnancy conditions other than nausea and vomiting were not associated statistically with breast cancer risk, these were only preliminary findings, he added, based mainly upon whether women "ever" experienced these conditions vs. "never" during any of their pregnancies. More nuanced experiences regarding these pregnancy-related characteristics will be the focus of future analyses, he said. Evidence from the current analysis did suggest that the lower risk of developing breast cancer observed with nausea and vomiting was stronger as the symptoms became more severe, or persisted longer into pregnancy. A modest trend toward increased cancer risk was observed in premenopausal women who gained more than 40 pounds during pregnancy, compared to those who gained less than 23 pounds, said Jaworowicz, but the trend didn't reach statistical significance. "Pregnancy is a time of drastic physiological changes, including rapid development and alterations in the breast tissue," he noted. "The rapidly changing anatomy of the breast makes it more susceptible to errors in DNA replication and/or repair, which may translate into breast cancer. "Associated with these changes are the fluctuating hormonal profiles that must be kept in a delicate balance. If the correct ratios and relative amounts between these hormones are not maintained within a normal range, certain pregnancy-related outcomes may emerge, such as high blood pressure, glucose intolerance and gestational diabetes, eclamptic conditions with seizures and/or toxemia, or extremely severe nausea. "These pregnancy-related factors may serve as indicators of underlying biological conditions that may influence a woman's lifetime risk for breast cancer." By recognizing that pregnancy-associated medical outcomes may provide easily accessible signals about core changes in the female physiology, future studies should continue to investigate and dissect the intricate relationship that may exist between readily observational perinatal factors, physiological characteristics and cancer risk, Jaworowicz said. "Subsequent analyses are planned to investigate the potential association between pregnancy characteristics and genetic polymorphisms of particular enzymes responsible for estrogen metabolism. This will help us to elucidate the potential link between pregnancy-associated conditions, hormonal exposures and breast cancer risk." Additional contributors to the research, from the Department of Social and Preventive Medicine, were Jo Freudenheim, Ph.D., the principal investigator for the study, Jing Nie, Ph.D., Matthew Bonner, Ph.D., Amy Millen, Ph.D., and Dominica Vito. Alan Hutson, Ph.D., chair of the Department of Biostatistics at UB and Roswell Park Cancer Institute; Christine B. Ambrosone, Ph.D., chair of Roswell Park's Cancer Pathology and Prevention section, and Paola Muti, M.D., now at Italy's National Cancer Institute in Genoa, also contributed to the research. The study was funded by a grant from the National Health Institute. The University at Buffalo is a premier research-intensive public university, the largest and most comprehensive campus in the State University of New York. UB's more than 27,000 students pursue their academic interests through more than 300 undergraduate, graduate and professional degree programs. Founded in 1846, the University at Buffalo is a member of the Association of American Universities. The School of Public Health and Health Professions is one of five schools that constitute UB's Academic Health Center. The University at Buffalo | |||||||||||||||||||||
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Related Breast Cancer News Articles M. D. Anderson study finds change in HER2 status after treatment with Herceptin Researchers at The University of Texas M. D. Anderson Cancer Center have discovered that when treated with Herceptin prior to surgery, 50 percent of HER2 positive, breast cancer patients showed no signs of disease at the time of surgery. M. D. Anderson study finds racial disparities in radiation therapy rates for breast cancer Black women are less likely than white women to receive radiation therapy after a lumpectomy, the standard of care for early stage breast cancer, according to a new study by researchers at The University of Texas M. D. Anderson Cancer Center. New nano device detects immune system cell signaling Scientists have detected previously unnoticed chemical signals that individual cells in the immune system use to communicate with each other over short distances. CSHL scientists identify new drug target against virulent type of breast cancer Tumor cells in a particular subset of breast cancer patients churn out too much of a protein called ErbB2 -- also often called HER2 -- which drives the cells to proliferate unchecked. Patients unlucky enough to be in this group -- about one in four -- have poorer prognoses and clinical outcomes than those who don't. Dense tissue promotes aggressive cancers New research may explain why breast cancer tends to be more aggressive in women with denser breast tissue. Breast cancer cells grown in dense, rigid surroundings step up their invasive activities, Vanderbilt-Ingram Cancer Center investigators report in the Sept. 9 issue of Current Biology. Women exposed to negative life events at greater risk of breast cancer: BGU study Happiness and optimism may play a role against breast cancer while adverse life events can increase the risk of developing the disease. Hormone replacement therapy improves sleep, sexuality and joint pain in older women One of the world's longest and largest trials of hormone replacement therapy (HRT) has found that post-menopausal women on HRT gain significant improvements in quality of life. Positive thinking may protect against breast cancer Feelings of happiness and optimism play a positive role against breast cancer. Research published today in the open access journal BMC Cancer suggests that while staying positive has a protective role, adverse life events such as the loss of a parent or close relative, divorce or the loss of a spouse can increase a woman's risk of developing the disease. Anti-tumor effects are enhanced by inhibiting 2 pathways rather than 1 Two independent research groups have found that simultaneous inhibition of two signaling pathways resulted in substantially enhanced antitumor effects in mouse models of prostate and breast cancer. In an accompany commentary, Steven Grant, at Virginia Commonwealth University Health Science Center, Richmond, discusses the clinical importance of these studies and highlights some of the questions that still need to be answered. Why a common treatment for prostate cancer ultimately fails Some of the drugs given to many men during their fight against prostate cancer can actually spur some cancer cells to grow, researchers have found. The findings were published online this week in a pair of papers in the Proceedings of the National Academy of Sciences. More Breast Cancer News Articles |
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