Tumors Smaller, Less Invasive With Screening Mammography

Pam Harrison

June 03, 2011

June 3, 2011 (Washington, DC) — Breast tumors that are detected on screening mammography in women 40 to 49 years of age are smaller and less likely to have nodal metastases than tumors found on physical examination. Results of a new study were presented here at the American Society of Breast Surgeons (ASBS) 12th Annual Meeting.

Paul Dale, MD, from the University of Missouri in Columbia, found that breast tumors detected on screening mammography in women 40 to 49 years of age were significantly smaller than those identified by physical exam (approximately 2 cm vs approximately 3 cm; P < .0001). In addition, more sentinel lymph nodes detected on screening mammography than detected on clinical examination were positive (56% vs 25%; P  .0001).

At 5 years, 94% of women whose breast cancer was detected on screening mammography were still free of disease, compared with 71% of those whose tumors were not detected by mammography. Overall survival at 5 years was also higher in those with tumors detected on mammography than in those with tumors that were not (97% vs 78%).

"The revised Preventative Service Task Force (USPSTF) mammography guidelines exclude women between 40 and 49 from routine mammography, which will potentially result in later disease diagnosis and poorer survival rates for this age group of women," Dr. Dale announced at a press conference held during the meeting. "Our study found that tumors identified through mammography generally had better outcomes after treatment than those found through clinical exams."

Mammography Results Systematically Reviewed

For the study, investigators identified women who were treated for breast cancer at their tertiary care center between 1998 and 2008. Women were divided into those who had their cancers detected by mammography and those who had their cancers detected clinically. Of the 1581 women treated for breast cancer at the tertiary center over the 10-year study interval, 320 women (20%) were between 40 and 49 years of age, Dr. Dale pointed out.

Nine patients were excluded from the study because of incomplete records, leaving 145 women in the mammography group and 166 in the clinical group.

Related Study Shows Similar Results

In a related study, Sharon Lum, MD, from Loma Linda University School of Medicine in California, identified 46,691 patients between the ages of 40 and 74 years who were diagnosed with ductal carcinoma in situ (DCIS) or early invasive breast cancer (T1N0) between 2004 and 2008. Both DCIS and T1N0 breast tumors are more likely to be detected on screening mammography, as Dr. Lum pointed out. All patients had records in the California Cancer Registry.

Of this large cohort, 22.6% of patients were between the ages of 40 and 49, and 77.4% were between the ages of 50 to 74 — "meaning that nearly one quarter of women in our study population would have been excluded from screening mammography [because of their age]," she explained. Results showed that women between the ages of 40 and 49 with DCIS were more likely to have hormone-receptor-positive breast cancer than women between the ages of 50 and 74.

Younger women with T1N0 disease were also more likely to have hormone-receptor-positive tumors than older women. In addition, they were more likely to be HER-2 positive than older women and to have triple-negative disease. Dr. Lum observed that younger women with DCIS were more likely to be of Hispanic or Asian/Pacific Islander race or ethnicity, and those with early invasive tumors were more likely to be of Hispanic or Asian/Pacific Islander background or to be non-Hispanic black.

Odds Ratios for Women Aged 40 to 49 vs Women Aged 50 to 74

Disease/Ethnic Background DCIS TIN0
Hormone-receptor positive 1.85 1.43
HER-2 positive NA 1.46
Triple-negative NA 1.67
Hispanic 1.62 1.82
Asian/Pacific Islander 1.50 1.66

"Excluding 40- to 49-year-old women from screening could have an impact on the early diagnosis of hormone-receptor-positive, HER-2, and triple-negative breast cancer, and could potentially lead to lost opportunities for targeted therapies in early-stage disease," Dr. Lum emphasized. "The adoption of these recommendations would disproportionately affect nonwhite women and potentially lead to more advanced-stage disease at the time of presentation."

Commenting on both studies, ASBS spokesperson Deanna Attai, MD, from the Center for Breast Care, Inc., in Burbank, California, told Medscape Medical News that society cannot ignore the fact that women between the ages of 40 and 49 develop breast cancer at a not-insignificant rate.

"We are not talking about 1 or 2 patients here; we are talking about a fair number of patients. What is striking is that the investigators really did show that women who did not undergo mammography had larger tumors, were more likely to have positive lymph nodes, and had poorer overall survival," she said. "I think this is important news and we are going to see more and more studies coming out that will continue to show the benefit of screening mammography in younger women."

The American Cancer Society, the American College of Surgeons, and the ASBS all to recommend routine screening mammography for women over the age of 40.

Despite this, a study to be presented at the American Roentgen Ray Society 2011 Annual Meeting has found that the USPSTF recommendations have already begun to affect the number of yearly mammograms done in women between 40 and 49 years of age. Compared with the previous year, for example, Lara Hardesty, MD, from the University of Colorado in Denver, counted 205 fewer women in the 40- to 49-year age group who underwent screening mammography in the 9 months following the release of the USPSTF guidelines.

"We must continue to get the message out to our patients and make sure that referring providers understand our recommendations because they are the ones who are influencing patients in that age group," Dr. Hardesty said in a news release.

Partial funding for Dr. Lum's study came from the National Cancer Institute. Dr. Dale, Dr. Lum, and Dr. Attai have disclosed no relevant financial relationships.

American Society of Breast Surgeons (ASBS) 12th Annual Meeting: Abstracts 1670 and 1754. Presented April 29, 2011.


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