Breast Cancer and the Environment on Long Island Follow-Up Study
University of North Carolina at Chapel Hill
Chapel Hill, N.C.
Dr. Marilie Gammon, of the University of North Carolina at Chapel Hill, and collaborating scientists in New York City, conducted a follow-up study on 1,098 women with breast cancer who participated in the parent population-based case-control study of Long Island women. The primary aims of the study were to determine whether environmental and other lifestyle factors influence breast cancer survival and overall survival among a population-based sample of Long Island women diagnosed with the disease.
The environmental and lifestyle factors under investigation included organochlorine compounds (including DDT/DDE, PCBs) and polycyclic aromatic hydrocarbons (PAHs), cigarette smoking, physical activity, hormone replacement therapy, adult weight gain, diet, alcohol consumption, and genetic and other personal susceptibility factors. (See parent study for information on DDT/DDE, PCBs, and PAHs.)
Study participants were interviewed and re-asked questions that had been administered as part of the parent study, including about lifestyle factors, personal and family medical history, and occupational and residential history. In this way changes in exposures that had occurred since diagnosis could be examined. Additionally, information about each woman's original breast cancer treatment and any recurrences was collected. The women were followed an average of 5 ½ years after breast cancer diagnosis.
The investigative team continues to analyze data collected in the study and publishes reports on the findings. One finding to emerge from the study indicates that adult weight gain is associated with decreased survival from breast cancer. In this analysis, Dr. Gammon and colleagues found that premenopausal women who gained more than 35 pounds after age 20 and before diagnosis with breast cancer were twice less likely to survive the cancer. Moreover, postmenopausal women who gained more than 29 pounds after age 50 and before diagnosis of the cancer were nearly three times less likely to survive.
"Obesity and weight gain in adulthood are modifiable risk factors for breast cancer occurrence and survival and our results show the importance of weight management, particularly during the perimenopausal and postmenopausal years in the prevention of excess mortality after menopause," write Dr. Gammon and co-authors in the published report of the findings. [Cancer Epidemiology, Biomarkers & Prevention, 2007]
Another finding from the study pertained to PAHs, a pollutant caused by incomplete combustion of various chemicals including diesel fuel and cigarette smoke. In the parent study, the investigative team had found that exposure to PAHs was associated with a modest 50 percent increased risk for breast cancer, which suggested the need for further research in other populations. The scientists had measured the level of binding of PAHs to DNA (forming what is called PAH-DNA adducts) in blood samples taken from the study participants. Formation of PAH-DNA adducts is believed to be necessary for cancer development. In this follow-up study, the investigators conducted a survival analysis that did not find strong support for the possibility of an association between detectable PAH-DNA adducts and an effect on survival among women with breast cancer. [Environmental Research, 2009]