New research findings published in the March issue of the Journal of the American College of Surgeons indicate that some breast cancers continue to be detected as a palpable lump rather than being found through mammographic screening. Patients who presented with palpable tumors -- those detected as a result of breast complaint or during examination -- had larger tumors and were at a more advanced stage at diagnosis.
The women who underwent yearly mammographic screening had the lowest rate of palpable presentation, in keeping with the reported benefit of mammography for early detection. Additionally, the data suggested that clinical breast examination (CBE) and breast self-examination should continue to play a role in detecting breast cancer.
Breast cancer is the second leading cause of death among women in the United States. The new breast cancer screening recommendations published in November 2009 by the U.S. Preventative Services Task Force (USPSTF) have been controversial because they now recommend against routine mammography screening for most women aged 40 to 49 years old. Additionally, the USPSTF concluded that current evidence is insufficient to assess the additional benefits and harms of CBE, beyond screening mammography in women 40 years or older, and recommended against teaching breast self-examination.
According to study investigator Amy C. Degnim, MD, FACS, associate professor of surgery, Mayo Clinic, Rochester, MN, a study by the Commission on Cancer in the 1990s showed that the percentage of breast cancer patients presenting with palpable masses decreased from 70 percent in 1983 to 44 percent in 1990. This decrease was most likely due to the increasing use of screening mammography, which aims to detect breast cancers before they are palpable. Little data has been published on the subject since 1990.
"We were a little surprised to find that the percentage of women with breast cancer who presented with a palpable lump hadn't changed much since 1990," Dr. Degnim said. "We found that 43 percent of breast cancers at Mayo Clinic Rochester in 2000 had a palpable presentation and most of the women had undergone some prior screening mammograms, but not always at the recommended annual interval."
Researchers also looked at the impact of the recent recommendations of the USPSTF to omit screening mammograms in women ages 40-49 in their study group. A total of 115 women were in the 40 to 49 age group in this study, with 67 breast cancers identified by the patients or their doctors and 48 found by mammography. Without mammography in this age group, at least 48 of the 115 cancers would have been missed, and many more would likely have been missed if both clinical breast examination and breast self-examination were also omitted.
"Screening mammograms play an important role in the detection of breast cancer at an earlier stage. We know that mammography does not pick up every breast cancer, however we were surprised at how often breast cancer was detected by a palpable mass," said Judy Boughey, MD, FACS, assistant professor of surgery, Mayo Clinic, Rochester, MN, and a co-investigator of the study. "Presentation as a palpable mass was more frequent in those women who had not had a mammogram in the prior 12 months. This finding is even more concerning when you consider the recent recommendations for decreasing the use of mammography because it would result in an even greater proportion of breast cancers being detected by palpation and therefore at more advanced stages."
Using an institutional surgical breast cancer database from the Mayo Clinic Rochester, the researchers evaluated 592 women who underwent breast surgery for cancer in the year 2000. Medical records were reviewed to identify the method of detection and dates of prior mammography screening. Patients whose cancer was detected by mammogram were compared with those whose tumors were detected by self-examination or clinical breast examination.
The method of cancer detection was screening mammogram in 335 patients (57 percent), a palpable mass in 255 patients (43 percent), and unknown in two patients (<1 percent). Eighty-one percent of the women (n=481) had at least one prior screening mammogram documented, although the majority of the screenings occurred at intervals longer than one year apart. Patients with no prior screening were significantly more likely to present with a palpable mass than those with a prior mammogram (67 percent vs. 39 percent, p=0.0002). The size of the tumor was significantly larger in women who detected the cancer via palpation versus those in whom it was detected via mammography (2.6 cm vs. 1.5 cm, p<0.0001).
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