Mammography Benefits Breast Cancer Survivors

Cancer Connect

by Dr. C.H. Weaver M.D. updated 9/2020

According to the results of a study published in the Journal of Clinical Oncology, surveillance mammography after treatment of early-stage breast cancer appears to improve survival, however mammography use declines over time among breast cancer survivors and efforts are needed to increase awareness among healthcare providers and breast cancer survivors regarding the value of follow-up mammography. (1,2)

Women who undergo breast-conservation therapy for breast cancer have an increased risk of developing breast cancer in their other breast during a 20-year period. Thus, women who have been diagnosed with breast cancer are encouraged to maintain a frequent screening schedule for breast cancer. Researchers from the University of Pennsylvania conducted a clinical study to evaluate the incidence of breast cancer in the contralateral breast among patients with early breast cancer who underwent breast-conserving therapy. This study included 1,801 women with early breast cancer treated with breast-conserving therapy between 1977 and 2000. (3)

  • 15.4% of patients were diagnosed with breast cancer in the contralateral breast.
  • The median time to developing contralateral breast cancer was 8.2 years.
  • The risk of developing contralateral breast cancer was similar among women whose initial diagnosis was ductal carcinoma in situ (DCIS) and women with more advanced breast cancer.
  • The risk of contralateral breast cancer persisted for at least 20 years.

Women who have undergone treatment for breast cancer are generally encouraged to receive regular surveillance mammograms in order to detect an early breast cancer recurrence or a new breast cancer. Few studies, however, have evaluated the effectiveness of surveillance mammography in reducing breast cancer mortality.

To explore the role of surveillance mammography in improving breast cancer survival, researchers conducted a study among 1,846 women age 65 or older who had been treated for Stage I or Stage II breast cancer.

During five years of follow-up, 178 women died of breast cancer. The frequency of surveillance mammography in the women who died of breast cancer was compared to the frequency of surveillance mammography in a matched comparison group of 634 women who had not died of breast cancer. Information about surveillance mammography was collected from medical records.

  • Each additional surveillance mammogram reduced the risk of breast cancer death by 31%. The protective effect of surveillance mammography appeared to be greatest for the oldest women.
  • Surveillance mammography was also linked with a reduced risk of death from causes other than breast cancer. While the reason for this result is uncertain, it’s possible that receipt of surveillance mammography is linked with better general medical care. It’s also possible that women who chose to receive a greater number of surveillance mammograms were healthier and would have had better survival even in the absence of mammography. The researchers attempted to account for this possibility by adjusting their results for factors such as age, breast cancer stage, and health conditions found in the medical records, but some residual bias is still a possibility.

This studies support recommendations for surveillance mammography among women treated for early-stage breast cancer.

Although mammography can detect second cancers at an early stage, it may be less accurate than among women who have never had breast cancer. To explore the performance of screening mammography among women with a personal history of breast cancer, researchers collected information about more than 100,000 screening mammograms. These mammograms were performed in roughly 19,000 women with a personal history of early-stage breast cancer and 55,000 women without a personal history of breast cancer.

  • As expected, the cancer rate per 1000 mammograms was higher among the women with a personal history of breast cancer than among without a personal history of breast cancer (10.5 versus 5.8).
  • The sensitivity of mammography (the ability of a mammogram to detect a cancer) was lower among women with a personal history of breast cancer. Screening mammography detected 65.4% of the breast cancers in women with a personal history of breast cancer and 76.5% of breast cancers in women without a personal history of breast cancer.
  • The breast cancers that were diagnosed in study subjects were predominantly early-stage.

These results suggest that mammography may be less accurate among women with a personal history of breast cancer. Nevertheless, the cancers that were detected tended to be early-stage, suggesting that mammography can detect early breast cancers regardless of prior history.The researchers note “Our findings support annual mammography screening recommendations in PHBC [personal history of breast cancer] women, but also highlight issues needing further evaluation.” It remains uncertain, for example, whether certain subgroups of women with a personal history of breast cancer would benefit from additional or alternative approaches to breast cancer screening.(4)

References:

  1. Lash TL, Fox MP, Buist DSM et al. Mammography surveillance and mortality in older breast cancer survivors. Journal of Clinical Oncology. 2007;25:3001-3006.
  2. Doubeni CA, Field TS, Ulcickas Yood M et al. Patterns and Predictors of Mammography Utilization Among Breast Cancer Survivors. Cancer. Early Online Publication April 24, 2006.
  3. Hill-Kayser CE, Harris EER, et al. Twenty-year incidence and patterns of contralateral breast cancer after breast conservation treatment with radiation. *International Journal of radiation Oncology*BiologyPhysics. 2006;66:1313-1319.
  4. Houssami N, Abraham LA, Miglioretti DL. Accuracy and outcomes of screening mammography in women with a personal history of early-stage breast cancer. JAMA. 305:790-799.
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