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Long Term Mammography Needed for Breast Cancer Survivors

(MedPage Today) –Regular surveillance mammography after breast cancer boosts survival and should be continued for at least a decade, a systematic review suggested.

Second cancers in the same or opposite breast occurred at a fairly constant rate over the first 10 years instead of being largely in the first two or three years as often thought, Clare Robertson, MSc, of the University of Aberdeen, Scotland, and colleagues found.

Mammographic follow-up to detect these tumors was associated with reduced all-cause mortality and breast cancer-specific mortality in the studies reviewed.

Because the analysis also presented favorable data regarding cost-effectiveness, the group argued online in Health Technology Assessment for routine surveillance mammography out to at least 10 years.

Action Points

  • Yearly surveillance mammography after breast cancer boosts survival and should be continued for at least a decade.
  • Note that surveillance mammography for breast cancer survivors appeared to be cost-effective.

Annual surveillance after breast cancer surgery is recommended in guidelines from the American Society of Clinical Oncology, and is common practice in both Britain and the United States.

The researchers surveyed 183 surgeons and radiologists at 105 British centers and found that most stopped following women with surveillance mammography (74%). Slightly over half said they stop at 10 years, though discontinuation at five years was also common at 35%.

Though surveillance schedules varied widely, follow-up mammography usually started at 12 months (87%), repeated annually (72%), and was coordinated using a symptomatic breast service (96%).

Most clinicians surveyed also reported discharging women from clinical follow-up (82%), typically at five years after breast cancer surgery (65%).

The researchers cautioned that their response rate was low (17% of 1,048 surveys sent out) but noted that the responses correlated fairly well with prior surveys on the topic and were likely representative.

The review also looked at the eight cohort studies that have reported on the mortality impact of surveillance mammography among breast cancer survivors.

All suggested a benefit of routine follow-up, though methods differed sufficiently to preclude pooled analysis.

All-cause mortality was 34% lower with yearly surveillance mammography than without it (age-adjusted odds ratio 0.66, 95% confidence interval 0.51 to 0.86) in one study.

Breast cancer-specific mortality was 72% lower with surveillance mammography (multivariate adjusted hazard ratio 0.28, 95% CI 0.22 to 0.37) in another study.

The smaller tumors that could only be found with imaging were associated with better survival odds than larger tumors among these women as well, the group reported.

Tumors larger than 20 mm in diameter — which represent about 80% of those detected with mammography done every three years — independently raised the relative risk of death 2.26-fold compared to those under 10 mm in diameter (95% CI 1.58 to 3.24).

Tumors with missing size data, which likely were those of women who did not have surgery, were associated with 3.19-fold higher risk of death (95% CI 2.24 to 4.53).

“While we have no information as to how these events were detected in clinical practice, the implication is that surveillance mammography may be of value,” Robertson’s group wrote, since it suggests, “that surveillance mammography could be used to reduce the size at which ipsilateral breast tumor recurrence or [second contralateral] cancers are detected.”

Yearly mammography alone, without additional clinical examination, appeared to be the regimen with the biggest net benefit and most likely to be considered cost-effective in the group’s economic analysis.

The incremental cost of yearly surveillance mammography was $7,364 (£4,727) per quality-adjusted life-year compared with no surveillance, falling well below the traditional British regulatory threshold of £30,000 for cost-effectiveness.

But for lower risk women, such as the 70-year-old in the scenario modelled, “it may be more cost-effective for surveillance to be performed less often (every two or three years) with mammography alone or another similarly less intensive and less costly test or combination of tests,” the group wrote.

They acknowledged the paucity of data available to go into the economic models, making it an exploratory analysis that should be interpreted cautiously.

By Crystal Phend, Senior Staff Writer, MedPage Today
Published: October 02, 2011
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner

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