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Radiologists and Surgeons Challenge the USPSTF Mammography Screening Guidelines

May 9, 2011

Studies released at recent meetings of the American Roentgen Ray Society (ARRS), the first and oldest radiology society in the US, and the American Society of Breast Surgeons are being promoted in the media as evidence against the USPSTF guidelines on mammography, though the study results don't actually give us answers about the benefits of mammography for women in their 40s.  In reality, these results may be good for women although the media and study investigators suggests otherwise. 

One study presented at ARRS reported a significant drop in mammograms for women aged 40-49 compared to the year before.  Researchers at the University of Colorado sent a survey to 303 primary care clinicians at the institution asking about screening mammography ordering practices in specific age groups before and after the release of the USPSTF guidelines in 2009.  The researchers found that the guidelines caused a significant drop in the screening mammography ordering practices of primary care clinicians for all three patient age groups (40-49, 50-74, >74).  56% of respondents recommended screening annually, 33% biannually, and 11% not at all in the 40-49 age group prior to the 2009 guidelines, and those numbers dropped to 20%, 18%, and 8% respectively, after the new guidelines.  Furthermore, 62% of the clinicians polled follow the new USPSTF guidelines to not recommend screening or discuss risks/benefits of screening with patients aged 40-49.

Along the same lines, a retrospective study at the University of Colorado found a statistically significant decrease in the number of women aged 40-49 who underwent mammography screening after the USPSTF guidelines were announced.  However, the number of women 50 years and older did not appear to change significantly.  The researchers used the mammography audit database to obtain the number of women aged 40-49 and 50 years and older who underwent screening mammography at the University of Colorado during two consecutive nine-month periods:  immediately before and after the guidelines’ release.   "In the nine months after the guidelines, we saw 205 fewer women in the 40-49 age group than we did the previous year," says Dr. Lara Hardesty, lead researcher for this study. 

Another abstract presented at the ARRS meeting touches on the potential impact of forgoing screening mammograms in the 40-49 population.  In a retrospective review of records, Dr. Donna Plecha and colleagues compared breast cancer stage at diagnosis in 40-49 year old asymptomatic women who underwent screening mammography to symptomatic women who presented for diagnostic mammography between January 1, 2008 and December 31, 2009. Out of 524 biopsies performed, 359 were in screening mammography patients and 165 were in symptomatic women.  54 cancers were detected in the screening group, and 55 in the symptomatic women.  Cancers found in women ages 40-49 who underwent screening presented at a much earlier stage of breast cancer than those patients who did not have screening mammograms.  However, there is no acknowledgement from the investigator that mammography is much better at finding non-lethal types of breast cancer, including ductal carcinoma in situ, which often doesn't progress to invasive breast cancer.

The recent annual meeting of the American Society of Breast Surgeons yielded two abstracts where scientists performed studies in response to the USPSTF recommendation.  A 10-year retrospective study of 1,581 women treated for breast cancer between 1998 and 2008 found that 20% of women diagnosed with breast cancer at this institution were under age 50, and 47% were diagnosed through mammography.  A comparison of 145 mammography-detected versus 166 clinically (manual) detected tumors found that non-mammographically identified tumors were 50% larger, more likely to have lymph node involvement, and had worse overall and breast cancer-specific survival compared to tumors detected by mammography.  According to lead investigator, Dr. Paul Dale of the University Of Missouri School Of Medicine, “Excluding women [ages 40 to 49] from routine mammograms will potentially result in later disease diagnosis and poorer survival.” However, the study wasn't actually designed to evaluate the impact of mammography on survival from breast cancer.

Another abstract presented at the American Society of Breast Surgeons meeting found that minority women were over-represented among those diagnosed with early breast cancer at ages 40 to 49.  In this retrospective study of 46,691 patients (10,566 ages 40-49) in the California Cancer Registry diagnosed between 2004 and 2008 with DCIS and extremely small  invasive cancers (T1N0), the researchers found that the women ages 40 to 49 with DCIS were more likely to be of Hispanic and Asian/Pacific Islander race or ethnicity.  Moreover, compared to Caucasian women, these women, as well as non-Hispanic black women, were more likely to be diagnosed with small invasive tumors.  Cancer in women ages 40 to 49 were also more likely than those in older patients (50-74) to be hormone receptor positive, HER-2 positive, and triple negative.  “By excluding these younger women from mammographic screening, you may be relatively diminishing the benefits of targeted therapies,” says author Dr. Sharon Lum of Loma Linda University School of Medicine.  Again, any conclusions about the value of mammography screening in younger women, and the impact on response to treatment and survival, cannot be drawn from the data.

These studies were published as abstracts at the conferences and data and conclusions have not yet undergone peer review for publication in a journal.