Regular mammograms may reduce breast cancer mortality by almost 50%
According to a new study, regular mammograms may decrease the risk for fatal breast cancer by 49%. The study was published by Dutch researchers online December 6 in the journal Cancer Epidemiology, Biomarkers, and Prevention. The researchers noted that the greatest reduction occurred in women aged 70 to 75 years and represented a drop of 84%.
"Our study adds further evidence that mammography screening unambiguously reduces breast cancer mortality," noted senior investigator Suzie Otto, PhD, from the Department of Public Health at Rotterdam's Erasmus Medical Centre, the Netherlands. Dr. Otto and her team reviewed data from 755 women aged 49 to 75 years who died of breast cancer from 1995 to 2003; these women were closely matched by age and screening occurrence with 3,739 control patients (5 per case).
Of the breast cancers detected, 29.8% were detected by screening mammogram, 34.3% were detected at intervals between screenings, and 35.9% occurred in women who had never had a mammogram screened (nonparticipants). In general, the breast cancer cases in nonparticipants were more advanced, with a rate of 29.5% for stage IV tumors compared with 5.3% for screen-detected cases and 15.1% for interval cases. In contrast, a regular screening mammogram was more likely to reveal early-stage localized tumors (34.2% vs. 10.8% for intervals and 10.3% for nonparticipants). As a result, women who had undergone three or more screening mammograms were 49% less likely to die from breast cancer on detection, relative to control patients.
The greatest benefit was found among women aged 70 to 75 years (84% decrease); however, the decrease in breast cancer mortality risk for the target population aged 50 to 69 years was significant (39%).
In the Netherlands, mammography screening is offered at no cost to women aged 50 to 75 years. The program is carried out by regional organizations that personally invite eligible women by mail to an appointment at a mobile screening unit. Dr. Otto noted, "The Dutch government considers it imperative that everyone eligible for a screening program is given the opportunity to participate. She added that the commensurate decrease in breast cancer mortality rates has been replicated in Europe and Australia. The authors feel these benefits may be duplicated in the U.S. with the presence of a government-funded program, which encourages preventive healthcare.
Over the course of a lifetime, 1 in 8 women will be diagnosed with breast cancer.
Risk factors one cannot change include:
Age and gender: The risk of developing breast cancer increases with ager. The majority of advanced breast cancer cases are found in women over age 50. Women are 100 times more likely to get breast cancer than men.
Family history of breast cancer: Women may have a higher risk of breast cancer if they have a close relative who has had breast, uterine, ovarian, or colon cancer. About 20-30% of women with breast cancer have a family history of the disease.
Genetic: Some women have genes that make them more prone to developing breast cancer. The most common gene defects are found in the BRCA1 and BRCA2 genes. These genes normally produce proteins that are cancer-protective. However, if a parent passes on a defective gene, the risk of breast cancer is increased. Women with one of these defects have up to an 80% chance of getting breast cancer sometime during their life.
Menstrual cycle: Women who start menstruating at an early age (before age 12) or experience a late menopause late (after age 55) have an increased risk for breast cancer.
Other risk factors include:
Alcohol consumption: Drinking more than 1 - 2 glasses of alcohol a day may increase the risk for breast cancer.
Childbirth: Women who have never had children or who had them only after age 30 have an increased risk for breast cancer. Being pregnant more than once or becoming pregnant at an early age reduces the risk of breast cancer.
Diethylstilbestrol: Women who took diethylstilbestrol (DES) to prevent a miscarriage may have an increased risk of breast cancer after age 40. This drug was given to the women in the 1940s - 1960s.
Hormone replacement therapy: Women who have been on hormone replacement therapy (HRT) for several years or more have a higher risk for breast cancer. Many women take HRT to reduce the symptoms of menopause.
Obesity: Obesity has been linked to breast cancer; however, this link is controversial. The theory is that obese women produce more estrogen, which can fuel the development of breast cancer.
Radiation: Women who received radiation therapy as a child or young adult to treat cancer of the chest area have a significantly higher risk for developing breast cancer. The younger the age that the radiation was given and the higher the dose, the higher the risk, especially if the radiation was given when a girl was developing breasts.
Breast implants, using antiperspirants, and wearing underwire bras do not raise the risk for breast cancer. There is no evidence of a direct link between breast cancer and pesticides.