Is MR imaging appropriate for the surgical management of breast cancer?

ABSTRACT: With a high sensitivity, MRI draws an accurate road map for planning surgical intervention. But the modality also suffers from a lack of evidence demonstrating an improvement in patient outcomes.

PHOENIX, Ariz.-Accurate local staging with imaging modalities is important for guiding breast cancer treatment in order to achieve clear margins and avoid recurrent disease.

But imaging also plays a part in detection of cancer in the contralateral breast. Whether MRI should be the go-to modality for staging primary disease and detecting contralateral breast cancer has yet to be determined.

The precise role and value of MRI in planning locoregional treatment and surgical management of breast cancer patients was debated at the 2009 Society of Surgical Oncology meeting.

On the pro side, Christiane Kuhl, MD, argued that MRI allowed for the most accurate delineation of size and extent of breast cancer. The modality also proves superior in detecting cancer in the contralateral breast, said Dr. Kuhl, vice chair, department of radiology and section chief, division of oncologic imaging and interventional therapy, at the University of Bonn, Germany.

On the con side, Monica Morrow, MD, stated that MRI does not improve outcomes, adds to the expense of treatment, and leads to unnecessary mastectomies. Dr. Morrow is the chief of breast service in the department of surgery and the Anne Burnett Windfohr chair of clinical oncology at Memorial Sloan-Kettering Cancer Center (MSKCC) in New York.

‘Breast surgeons require MRI’
MRI provides the most accurate road map for planning breast surgery in cancer patients, according to Dr. Kuhl. It has the highest sensitivity for depicting the size and local extent of breast cancer, including multifocal, multicentric, or contralateral disease. It is also useful for delineating intraductal extensions of breast cancers.

“We use MRI not only for patients with lobular cancer but also in those with ductal invasive cancer. There is increasing evidence that MRI is far more sensitive in delineating intraductal components (of breast cancers) than mammography or ultrasound,” Dr. Kuhl said.

She noted that MRI is extremely useful in finding additional multicentric breast cancer that would have been otherwise occult, as well as screening the contralateral breast for cancer in high risk women.

“This is the reason why our breast surgeons require breast MRI to be done in every patient with biopsy-proven cancer. We have daily dedicated time slots reserved for urgent, same day preoperative breast MRI studies. So there is no delay for surgery,” Dr. Kuhl said.

She explained that to be certified as a breast center, her institution must comply with European Union guidelines that state patients must undergo surgery within 10 days after a biopsy-proven cancer.

MR for diagnosis not screening
Dr. Kuhl said that a number of arguments against the use of preoperative MRI point out that there is lack of data on morbidity and recurrence rates. Furthermore, use of MRI in this context needs to be supported by the results from randomized trials.

Dr. Kuhl stressed that MRI is used in this context for staging; it’s a diagnostic tool rather than a screening modality. “Using MRI to find out the actual extent of disease doesn’t require randomized trials to support its use,” said said. “Randomization is only required to establish new therapeutic interventions or screening trials, but is not required to establish a new diagnostic test.”

She cited guidelines by the Oxford Institute of Evidence-based Medicine that only require randomized trials for establishing new therapies or screening but not for diagnostic situations.

“For diagnosis, a test only has to be consistently superior to current or established diagnostic tests. And there are a number of trials that show MRI is far more accurate in delineating the extent of known cancer compared with mammography or ultrasound,” she added (J Natl Compr Canc Netw 7:193-201, 2009; Top Magn Reson Imaging 19:143-150, 2008; Cancer 113:2408-2414, 2008).

Finally, using MRI allows clinicians to proceed straight to MRI-guided vacuum biopsy, which can often be done in the same diagnostic session. “MRI-guided vacuum biopsy is available to clarify additional lesions so there is no unnecessary anxiety for the patients and no unnecessary mastectomies for false-positive MRI findings. Also, there is no unnecessary cosmetic compromise due to additional excisional biopsies,” Dr. Kuhl said.

The overtreatment issue
Dr. Kuhl also acknowledged that critics also say that staging with MRI may lead to overtreatment of women and unnecessary mastectomies in particular. While she accepted that overtreatment can be an issue when using MRI to diagnose additional lesions in the same breast, “current guidelines for management of multicentric breast cancer are based on mammographic staging alone.”

“Overtreatment can indeed occur if these guidelines are inappropriately used to guide treatment decisions in patients with MRI-detected multicentric disease,” she said.

Rather than thoughtlessly applying guidelines based on mammography to patients with multicentric disease based on diagnostic MRI, each treatment decision should be individualized to the patient, Dr. Kuhl proposed.

While MRI can detect additional cancers in the breast, but it’s also likely that these additional cancers can be treated by whole breast radiation, she noted. The mere detection of an additional cancer does not mean treatment must be changed to mastectomy, according to Dr. Kuhl.

“We propose mastectomy only for large additional invasive cancers or those with extensive intraductal components,” she said.

Dr. Morrow acknowledged that MRI does indeed find areas of cancer that are not evident on other imaging modalities or by physical exam. “However, I contend that the purpose of any diagnostic test is to provide information that improves patient outcomes and there is little evidence that patient outcomes are improved with MRI,” she said.

Achieving improved outcomes in staging cancers means having negative margins on first lumpectomy and decreasing the rate of unplanned mastectomies, Dr. Morrow said. “We now have several studies that have looked at whether MRI reduces negative margins and there is no evidence that MRI improves outcomes,” she added.

Dr. Morrow also noted the findings of studies such as the multicenter COMICE trial showed that MRI does not reduce re-operation rates. In the UK-based COMICE trial, 1,625 patients were randomized to receive MRI or not between 2001 and 2007.

Re-operation rate within six months (primary outcome) was 18.8% for those who underwent MRI and 19.3% for those patient who did not (SABCS 2008 abstract 51).

At least two studies have also shown that MRI does not affect unplanned conversion from breast conservation to mastectomy, she said (2008 ASCO Breast Cancer Symposium abstract 227; Breast Cancer Rest Treat online, September 21, 2008).

Also, Dr. Morrow noted the findings of a 2007 study led by Constance D. Lehman, MD, PhD, and colleagues that showed that MRI can detect cancer in the contralateral breast missed by mammography and clinical exam in 3.1% of women followed for one year. She observed that one-year follow-up may not be sufficient to truly assess outcomes (New Engl J Med 356:1295-1303, 2007).

She also noted the findings of a 2008 retrospective study led by Lawrence J. Solin, MD, that followed women for almost five years and found that there were no differences in outcomes between those who had breast MRI for diagnosis and evaluation and those who had routine breast imaging.

Outcomes in the study included local failure or contralateral cancer (J Clin Oncol 26:386-391, 2008).

“When the researchers looked at both groups, they were basically identical in terms of benefit,” Dr. Morrow said.

No standards to guide mastectomy
Dr. Morrow noted that MRI in the newly diagnosed breast cancer patient increases mastectomy rates overall. She also said there are currently no standards for interpreting MRI-detected breast cancers and deciding whether or not to convert to mastectomy, and that’s a hazard in treatment of breast cancer patients. “The danger is that this technique has been advocated and put into practice without finding out at what point the tumor burden should be ignored,” she said.

Dr. Morrow pointed out that studies done in the U.S. have shown that MRI can delay definitive surgery by three weeks. For instance, a review of 600 breast cancer patients at Philadelphia’s Fox Chase Cancer Center showed that MRI increased the odds ratio for mastectomy to 1.8 compared with patients who did not have the imaging study and delayed pre-treatment evaluation by more than three weeks and was associated with no decrease in the rate of positive surgical margins after lumpectomy (2008 ASCO Breast Cancer Symposium abstract 227).

Although Dr. Morrow did not cite this research in her talk, another study conducted by Carol Lee, MD, found that patients who underwent MRI before initial surgical treatment did have their therapy changed to mastectomy, more extensive lumpectomy, or treatment of the additional lesions in the contralateral breast. Adding an MRI examination also delayed treatment with the mean interval between diagnosis and definitive surgery in the group that had the MRI exam coming in at 41 days compared to 27 days for the patients who did not undergo an MRI (2008 American Roentgen Ray Society abstract 113).

“What does MRI do? It increases the cost of care due to additional imaging, biopsies for benign disease and a very high rate of short interval follow-ups in this country,” she said. “What doesn’t MRI do?” Dr. Morrow added. “It doesn’t improve patient outcomes.”