Imaging for Distant Metastases in Early-stage Breast Cancer

Alexander M. Castellino, PhD

December 22, 2014

Despite a recommendation against imaging for distant metastases in patients with early-stage breast cancer, and the fact that it was part of the American Society of Clinical Oncology's (ASCO) 2012 list of five cancer practices that must stop, the practice continues.

Women with early-stage breast cancer are still undergoing imaging for distant metastases, according to a study conducted in Ontario, Canada's largest province, and presented at the San Antonio Breast Cancer Symposium 2014 in San Francisco.

That study corroborates a single-center study published online November 12 in the Journal of Oncology Practice, which also shows that imaging continues.

"The results of this study demonstrate that the majority of patients with early-stage primary operable breast cancer continue to have a significant amount of imaging to look for distant metastases, which is not in keeping with our provincial guideline or the spirit of the ASCO top-five recommendation," according to Demetrios Simos, MD, who was involved in both studies and was at the Ottawa Hospital Cancer Centre in Ontario at the time.

In the single-center study, "there did not appear to be any appreciable change in practice patterns after the publication of the inaugural ASCO top-five list," Dr Simos told Medscape Medical News. He is currently a medical oncologist at the Stronach Regional Cancer Centre in Newmarket, Ontario.

"I am disappointed, but not surprised," said Lowell E. Schnipper, MD, chief of hematology/oncology at the Beth Israel Deaconess Medical Center in Boston, and chair of the ASCO Value in Cancer Care Task Force.

"It would be great if we understood what drives physician behavior," he told Medscape Medical News. He said from his own experience, he believes that ordering unnecessary tests is multifactorial. Physicians need to feel they are on top of the case, but patients are terrified and want to be sure they do not have cancer all over, he said.

ASCO Recommendation Against Imaging

Dr Schnipper was involved in the development of ASCO's 2012 list of the top five practices in oncology that must stop (J Clin Oncol. 2012;30:1715-1724), which was part of the Choosing Wisely campaign, an initiative led by the American Board of Internal Medicine Foundation to encourage conversations between physicians and patients about the overuse or misuse of medical tests.

On that list is the following recommendation: Do not perform PET, CT, or radionuclide bone scans in the staging of early breast cancer at low risk for metastasis."

In breast cancer, "there is a lack of evidence demonstrating a benefit for the use of PET, CT, or radionuclide bone scans in asymptomatic individuals with newly identified ductal carcinoma in situ (DCIS) or clinical stage I or II disease. Unnecessary imaging can lead to harm through unnecessary invasive procedures, overtreatment, unnecessary radiation exposure, and misdiagnosis," Dr Schnipper and his colleagues write.

Population Study From Ontario

"The publication of the ASCO top-five list highlighted the issue of unnecessary staging imaging in early-stage breast cancer and served as the impetus for this study," Dr Simos explained.

In it, he and his colleagues quantified the rates of staging imaging in women with early-stage breast cancer in Ontario.

The team identified 50,924 patients diagnosed with breast cancer from January 2007 to December 2012 from the Institute for Clinical Evaluative Sciences (ICES) registry, 36,812 of whom were diagnosed with stage I, II, or III disease. Data were available for all imaging from the day of diagnosis until 3 months after breast cancer surgery.

In patients with early-stage breast cancer, 89.3% received imaging and 54.7% received clarification imaging. On average, patients underwent 2.86 imaging tests and 1.97 tests for clarification.

Overall, 82.8% of women with stage I disease underwent imaging for distant metastases, as did 93.4% of women with stage II disease and 97.5% of women with stage III disease.

Women were more likely to undergo imaging if disease stage was higher at diagnosis, they were younger, they underwent breast MRI, they were treated in a nonacademic hospital, or they had HER2 overexpression, Dr Simos reported

Single-Center Study

In their pilot study, Dr Simos and colleagues retrospectively compared imaging in two groups of patients with primary operable (early-stage) breast cancer who had undergone surgery at the Ottawa Hospital Cancer Centre.

The 100 women in the first group were treated in 2011, before the top-five list was issued. The 100 in the second group were treated at least 4 months after the list was issued.

There was no difference in the proportion of women who underwent at least one imaging test to investigate for distant metastases in the pre- and postlist groups (83% vs 86%).

Table. Imaging for Distant Metastases

Imaging Prelist Group, % Postlist Group, %
Stage I disease    
   Perioperative 71.4 78.6
   Clarification/confirmation 12.5 33.3
Stage II disease    
   Perioperative 97.1% 88.9
   Clarification/confirmation 35.3 35.0

 

The majority of staging imaging was performed preoperatively, not postoperatively. Almost all preoperative staging imaging was ordered by the surgeon (90.1%). Most postoperative clarification/confirmation imaging was ordered postoperatively by the medical oncologist (53.8%), the radiation oncologist (23.5%), and the surgeon (17.6%).

Significantly, imaging detected no metastatic disease in patients with stage I or II disease, supporting the recommendation not to use imaging in this setting.

Of the 22 women (11%) in the study population with stage III disease, metastatic disease was detected in 2, both of whom had pathologic stage IIIC disease.

Four months might not have been long enough for the recommendations on the top-five list to make it into clinical practice, Dr Schnipper noted.

Dr Simos explained that when the recommendation against routine staging imaging in women with early-stage breast cancer was published online, it was discussed during multidisciplinary breast cancer rounds at the Ottawa Hospital Cancer Centre.

He argued that the majority of medical, radiation, and surgical oncologists who treat breast cancer were made aware of it, and said he feels that the 4-month window was adequate for them to read and become familiar with the recommendation.

In fact, a survey by Dr Simos and his colleagues found that the majority of radiation, medical, and surgical oncologists were aware of and in agreement with the recommendations pertaining to staging imaging for early breast cancer (J Eval Clin Pract. Published online October 14, 2014).

Reasons for Lack of Guideline Adherence

Adherence is a different kettle of fish. "Lack of adherence is likely multifactorial," Dr Simos told Medscape Medical News.

In general, physicians tend to be receptive to guidelines. The literature suggests that most believe that guidelines are a helpful source of advice, a valuable educational tool, a means for improving the quality of care, and sufficiently practical to apply to their patients, he reported.

However, this can be counteracted by the relatively easy access to imaging (especially in the context of investigating a malignancy), institutional practice patterns, lack of awareness of the evidence/recommendations, deficiencies in training, patient demand for imaging, comfort and/or reassurance prior to initiating potentially intensive and toxic therapy in the adjuvant setting, and the use of disease biology rather than disease stage as a driver of imaging, Dr Simos explained.

Much Needs to Be Done

Alternative strategies, beyond simply publishing recommendations, might be required for a sustained change in physician practice, he noted.

Dr Schnipper said he concurs. Changing clinical practice patterns is challenging, and additional strategies are required to change physician behavior, he said.

The magnitude of the use of imaging points to a huge savings opportunity without compromising care, he said.

The routine use of imaging to look for distant metastases in early-stage breast cancer should be discouraged because the likelihood of detecting radiologically evident metastases is small, Dr Simos said.

He reported that the likelihood of detecting radiologically evident metastases in asymptomatic women with early breast cancer is approximately 0.2% for patients with stage I disease and 1.2% for those with stage II disease.

This "pick-up" rate must be balanced against the much higher likelihood of a false-positive finding that will invariably lead to further clarification/confirmatory imaging and perhaps even an invasive procedure, such as biopsy, to confirm or exclude the suspicious finding, he added.

In the context of a false-positive test, all bets are off. The pattern of care is radically altered from one where physicians typically treat for a cure in early-stage disease, Dr Schnipper said.

In the United States, reimbursement should be linked to a value-based insurance design where promiscuous testing should have an impact on physician reimbursement and patient copay, Dr Schnipper explained.

We should be able to use market forces to encourage the right behavior, he said.

Dr Simos and Dr Schnipper have disclosed no relevant financial relationships.

San Antonio Breast Cancer Symposium (SABCS) 2014: Poster P1-10-01. Presented December 10, 2014.

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