20 Months Total Breast-Feeding May Lower A Woman's Risk Of Developing Breast Cancer

December 02, 1997

BUFFALO, N.Y. -- Breast-feeding for at least 20 months during their lifetime appears to offer women some protection against developing breast cancer later in life, a study by epidemiologists at the University at Buffalo has found.

Results of their case-control study involving 1,313 women showed that premenopausal women had a 50 percent lower risk of breast cancer if they had breast-fed for at least 20 months, compared to women who had at least one baby and had not breast-fed. There was no effect of breast-feeding on the risk of breast cancer for women who were postmenopausal at the time of the study.

The study is published in the Dec. 2 issue of the American Journal of Epidemiology, which is dedicated to research by faculty members and graduates of the UB Department of Social and Preventive Medicine.

"This is one of a number of studies now that show a decreased risk of breast cancer with breast-feeding," said Jo L. Freudenheim, Ph.D., UB associate professor of social and preventive medicine and primary researcher on the study.

"There is some question, however, about whether this is related to how long a woman breast-feeds, to inherent breast problems in women who don't succeed in breast-feeding when they try, to treatments to stop milk production or just to cessation of menstruation.

"This study shows that breast-feeding is protective, but the effect appears only if women breast-feed over a longer period of time," Freudenheim said. Breast-feeding time was measured in cumulative months during a lifetime.

UB researchers analyzed health history and breast-cancer risk factors of 250 premenopausal women and 367 postmenopausal women who had been diagnosed with primary breast cancer between 1986 and 1991, along with data from 693 cancer-free women who served as a control group. All women had at least one live birth, and cases and controls were matched by age.

The women were interviewed in person about a number of potential breast-cancer risk factors, including whether they had breast-fed their infants, how long they breast-fed, why they

had stopped and whether those who did not breast-feed had received medication to stop milk flow.

Adjusting for other breast-cancer risk factors, the researchers found that breast-feeding appeared to provide a decrease in risk, but only for premenopausal women who had breast-fed for at least 20 months.

Freudenheim said one explanation for this finding may be the possibility that earlier pregnancy and breast-feeding may cause breast tissue to go through a development phase that makes it less susceptible to carcinogens. Conversely, late first pregnancy long has been considered a risk factor for developing breast cancer.

There was no indication that women who stopped breast-feeding because of insufficient milk supply, or who had received treatment to stop milk flow, were at increased risk, Freudenheim said.

Additional researchers on the study were Saxon Graham, Ph.D.; John Vena, Ph.D.; Kirsten Moysich, Ph.D.; Paola Muti, Ph.D., and Rosemary Laughlin, Ph.D., all from the UB Department of Social and Preventive Medicine; Takuma Nemoto, M.D., from the UB Department of Surgery, and James Marshall, Ph.D., formerly of the UB Department of Social and Preventive Medicine, now at the Arizona Cancer Center.

University at Buffalo

Related Breast Cancer Articles from Brightsurf:

Oncotarget: IGF2 expression in breast cancer tumors and in breast cancer cells
The Oncotarget authors propose that methylation of DVDMR represents a novel epigenetic biomarker that determines the levels of IGF2 protein expression in breast cancer.

Breast cancer: AI predicts which pre-malignant breast lesions will progress to advanced cancer
New research at Case Western Reserve University in Cleveland, Ohio, could help better determine which patients diagnosed with the pre-malignant breast cancer commonly as stage 0 are likely to progress to invasive breast cancer and therefore might benefit from additional therapy over and above surgery alone.

Partial breast irradiation effective treatment option for low-risk breast cancer
Partial breast irradiation produces similar long-term survival rates and risk for recurrence compared with whole breast irradiation for many women with low-risk, early stage breast cancer, according to new clinical data from a national clinical trial involving researchers from The Ohio State University Comprehensive Cancer Center - Arthur G.

Breast screening linked to 60 per cent lower risk of breast cancer death in first 10 years
Women who take part in breast screening have a significantly greater benefit from treatments than those who are not screened, according to a study of more than 50,000 women.

More clues revealed in link between normal breast changes and invasive breast cancer
A research team, led by investigators from Georgetown Lombardi Comprehensive Cancer Center, details how a natural and dramatic process -- changes in mammary glands to accommodate breastfeeding -- uses a molecular process believed to contribute to survival of pre-malignant breast cells.

Breast tissue tumor suppressor PTEN: A potential Achilles heel for breast cancer cells
A highly collaborative team of researchers at the Medical University of South Carolina and Ohio State University report in Nature Communications that they have identified a novel pathway for connective tissue PTEN in breast cancer cell response to radiotherapy.

Computers equal radiologists in assessing breast density and associated breast cancer risk
Automated breast-density evaluation was just as accurate in predicting women's risk of breast cancer, found and not found by mammography, as subjective evaluation done by radiologists, in a study led by researchers at UC San Francisco and Mayo Clinic.

Blood test can effectively rule out breast cancer, regardless of breast density
A new study published in PLOS ONE demonstrates that Videssa® Breast, a multi-protein biomarker blood test for breast cancer, is unaffected by breast density and can reliably rule out breast cancer in women with both dense and non-dense breast tissue.

Study shows influence of surgeons on likelihood of removal of healthy breast after breast cancer dia
Attending surgeons can have a strong influence on whether a patient undergoes contralateral prophylactic mastectomy after a diagnosis of breast cancer, according to a study published by JAMA Surgery.

Young breast cancer patients undergoing breast conserving surgery see improved prognosis
A new analysis indicates that breast cancer prognoses have improved over time in young women treated with breast conserving surgery.

Read More: Breast Cancer News and Breast Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.