March 22, 2014
Some Women Might Benefit From More Frequent Mammograms
April Flowers for redOrbit.com - Your Universe Online
While three-year intervals between mammograms are appropriate for most women, a new study from the UK NHS Breast Screening Program has found that one-third of women are at a higher risk of developing cancer. These women, according to the report delivered this week at the 9th European Breast Cancer Conference (EBCC-9), might benefit from more frequent mammograms.
The participants completed a questionnaire on important breast cancer risk factors such as family history and lifestyle, as well as donating DNA by saliva when appropriate. The researchers measured breast density from the mammogram and gave a "visual assessment score" (VAS), which indicated the percentage of dense tissue in the breast. The researchers began collecting data in 2009, and the report given at EBCC-9 included the results of the first 53,467 participants. During the study period, 634 women in the study developed breast cancer.
Women between the ages of 47 and 73 are welcome in the NHS Breast Screening Program. The normal risk of developing breast cancer within the next ten years varies from 2.4% at the age of 47 to 3.5% at the age of 70.
From the questionnaire, the researchers learned that 676 (1.4 percent) women had a high risk of developing breast cancer of the next ten years (8 percent or more). An additional 4591 (8.6 percent) of the women had a moderately increased risk of between five and eight percent.
Breast tissue thins as women age, and a high percentage of dense tissue at older ages is a risk indicator for developing cancer. The VAS revealed that 60 percent or more of breast tissue was dense in 5.2 percent of the participants. They also found that women with the highest, age adjusted percentage of dense tissue were nearly 3 times as likely to develop breast cancer in the next ten years than women with the lowest density.
To make the results more accurate at defining risk, the research team combined the results of the survey and the VAS. These combined results revealed that 1,280 (two percent) of women had a high risk (eight percent or more) of developing breast cancer with 29 (2.3 percent) developing breast cancer. Another 14,720 women had an above average risk (over 3.5 percent) of developing breast cancer in the next ten years. These results were born out when 267 (1.8 percent) had developed breast cancer in the four-year period from 2009. The remaining 36,748 women had an average or below average risk, and of these, only 371 (1 percent) developed breast cancer during the four years of the study.
In the average to below average risk group, the researchers found that only 45 cancers that had started to spread to the lymph nodes were found during the four years, which was equivalent to about three per 100,000 women a year. This is compared to around 11 per 100,000 women a year in those at above average risk.
Prof Evans, chief investigator for the PROCAS study, said, "Our results suggest that three-yearly screening is very effective for around 70% of the female population, but that those women who have a higher than average risk of developing breast cancer probably require more frequent screening, particularly as more advanced cancers were detected in these women. Screening should be annual for the small proportion of women who have an eight percent or greater risk of developing cancer over the next ten years."
"This is the largest study of its kind in the UK, and the results could have an impact on the whole NHS Breast Screening Program. By incorporating this process of personal risk assessment into routine screening practice we can predict and prevent more breast cancers in the future."
Dr Hilary Dobson, chair of EBCC-9's national organizing committee and Clinical Lead of the West of Scotland Breast Screening Service and the Lead Clinician of the West of Scotland Cancer Advisory Network (WoSCAN), commented, "These are important findings in the context of considering how best to deliver an effective, yet safe, population-based screening program. To date, the UK NHS Breast Screening Program has been organized on the basis of using age as a risk factor to identify the eligible, target population. As our understanding of the contribution of familial risk has improved, there has been a move to align such cases with the national screening program. This study takes the process one step further towards the concept of more personalized screening – a model taking account of a range of personalized risk factors resulting in an individualized screening frequency. Longer follow-up of the affected individuals will add weight to any future requirement to change from the current delivery model of the national screening program."