The majority of deaths resulting from breast cancer occur in younger women who do not have regular mammograms, according to a study published in the journal Cancer.
According to the
Researchers from Harvard Medical School in Boston conducted an analysis of the value of mammography screening, using a technique called "failure analysis."
This technique evaluates breast cancer cases backward from death, in order to determine correlations at diagnosis, rather than looking forward from the beginning of a study.
Invasive breast cancer cases that were diagnosed at Partners HealthCare Hospitals in Boston between 1990 and 1999 were evaluated for the study. The researchers analyzed the patients':
- Mammography use
- Surgical and pathology reports, and
- Recurrence and death dates.
Half of breast cancer deaths in under-50s
Out of 609 confirmed deaths from breast cancer, only 29% of the women had been screened with mammography, while 71% were unscreened.
Of all breast cancer deaths, 13% occurred in women over the age of 70, while 50% occurred in women under the age of 50.
The women diagnosed with breast cancer who then died were a median age of 49 at diagnosis. Those who died from any other cause had a median diagnosis age of 72.
Dr. Blake Cady, professor of surgery (emeritus) of Harvard Medical School, says:
"The biological nature of breast cancer in young women is more aggressive, while breast cancer in older women tends to be more indolent.
This suggests that less frequent screening in older women, but more frequent screening in younger women, may be more biologically based, practical, and cost effective."
Mammograms provide increased survival rates
The study also showed that since the introduction of breast cancer screening in 1969, survival from the disease has significantly increased.
In 1969, 50% of women who had breast cancer died 12.5 years after diagnosis, compared with only 9.3% of women from this study, who were diagnosed between 1990 and 1999.
"This is a remarkable achievement, and the fact that 71% of the women who died were women who were not participating in screening clearly supports the importance of early detection," adds Daniel Kopans of Harvard Medical School and Massachusetts General Hospital.
'More focus' on screening younger women
In 2009, the US Preventive Services Task Force proposed that mammography should be limited to women aged between 50 and 74. But research from the Mayo Clinic last year revealed that the number of women in their 40s who have mammographies has dropped by 6% nationwide since the recommendation.
The researchers say that given the findings of this research, there should be less focus on ensuring older patients are screened, and more focus on younger women.
"Detecting and treating breast cancer in younger women to prevent death may further increase the disease-free life years saved," say the study authors.
"Our findings suggest decreasing the intensity of efforts to screen women older than 69 years while concomitantly emphasizing efforts to screen younger women in particular."
However, other studies have shunned the use of mammograms. Research from The Dartmouth Institute for Healthy Policy & Clinical Practice in Lebanon suggested that mammograms are ineffective at lowering breast cancer death rates and that the process can lead to over-diagnosis.