Diagnostics & Imaging Week National Editor
Can medical diagnosis be too aggressive?
The answer "yes" was given recently, with a recommendation in August against screening of older men for prostate cancer, given the slow growth of the disease and the threat of treatment bringing death earlier than watchful waiting.
And a new study reported at the 2008 Breast Cancer Symposium of the American Society of Clinical Oncology (ASCO; Alexandria, Virginia), which concluded this past weekend in Washington, indicates that the use of MRI for follow-on diagnosis to guide treatment of breast cancer may encourage women to have mastectomies that aren't necessary.
In essence, the study says that the unneeded mastectomies result from the high sensitivity of MRI which produces a large number of false positives.
The study notes that the routine use of MRI scans in women newly diagnosed with the disease increased significantly from 2004 to 2005 and again in 2006.
Richard Bleicher, MD, a specialist in breast cancer surgery at Fox Chase Cancer Center (Philadelphia), said, "We have yet to see any evidence that MRI improves outcomes when used routinely to evaluate breast cancer and yet more and more women are getting these scans with almost no discernable pattern."
Bleicher acknowledged the greater sensitivity of MRI scans but said this leads to a high number of false positives, and he pointed also to the higher costs for the procedure. "For most women, an MRI scan prior to treatment is unnecessary," he said, and that more studies are needed to determine their usefulness in improving outcomes for patients.
Bleicher and colleagues reviewed the records of 577 breast cancer patients seen in what was termed a multidisciplinary breast clinic. The women were evaluated by a radiologist, pathologist, and a surgical, radiation, and medical oncologist. Of this group of patients, 130 had MRIs prior to treatment.
Bleicher said many of the women who went on to receive mastectomies could have been candidates for the much less draconian – and much less invasive – lumpectomy procedure.
"Rather than having a biopsy to see if those findings [of cancer] are real, women and their doctors may choose mastectomy out of an abundance of caution. Other studies have demonstrated that this often represents over-treatment because many of the mastectomies are later proven by pathology to have been unnecessary."
The study also revealed that younger women were more likely to have an MRI.
"In our analysis, that trend didn't correspond with various breast cancer risk factors, such as a family history of breast or ovarian cancer, nor with the characteristics of their disease," Bleicher said.
Another conclusion from the research is that MRI failed to help surgeons decrease positive margins during surgery, another benefit that has been hypothesized for the use of MRI.
"MRI is a valuable tool in some women, but without evidence that routine pre-treatment MRI improves a woman's outcome, its disadvantages suggest that it should not be a routine part of patient evaluation for treatment," said Bleicher. "Greater efforts to define MRI's limitations and use are needed."
The study was supported by a U.S. Public Health Service grant and by an appropriation from the Commonwealth of Pennsylvania.
Fox Chase Cancer Center was founded in 1904 in Philadelphia as the nation's first cancer hospital and was one of the first institutions to be designated a National Cancer Institute Comprehensive Cancer Center in 1974.
In another report from the ASCO conference, Xoft (Sunnyvale, California) issued data from a study saying that the early clinical experience with its FDA-cleared Axxent Electronic Brachytherapy (eBx) System demonstrates that this X-ray-based, non-isotopic treatment is a viable option for adjuvant therapy for early-stage breast cancer.
The Phase IV study, "Early experience with an electronic brachytherapy technique for intracavitary accelerated partial breast irradiation," was presented in poster discussion by Vivek Mehta, MD, director of the Center for Advanced Targeted Radiotherapies at Swedish Cancer Center (Seattle, Washington) was designed to evaluate the safety/effectiveness of the Axxent System for early-stage breast cancer.
Study patients received an accelerated course of radiation treatment delivering 3.4 Gy/fraction, twice a day for five days, with the primary endpoint being the successful delivery of the prescribed radiation therapy, the secondary endpoint the collection of adverse device-related events.
Interim results on 38 patients who completed treatment showed that 25 of these patients had been followed for a minimum of one month post-treatment. In this group, the eBx treatment was successfully delivered in every patient for every fraction. And the side effects of treatment reported were described as "generally mild, manageable, and expected."
In its treatment of early stage breast cancer, the Axxent system provides the opportunity to reduce the therapy time required from seven weeks (for external radiation therapy) to five days, enabling greater access to therapy, according to the company. "This may accelerate patient choice of breast-sparing lumpectomy surgery with adjuvant radiation therapy over the alternative of a full mastectomy," it said in a statement.
Mehta, the principal investigator, said, "While we will be monitoring these patients for the next five years, this data is very exciting as it confirms what we as investigators hoped it would from the start — that electronic brachytherapy is a safe and clinically promising alternative for accelerated partial breast irradiation. Because this method delivers therapy electronically, without the use of radioactive isotopes, it eliminates the need for the heavily-shielded vaults required by existing radiation therapy technologies. Radiation oncology centers now have a new solution for providing partial breast radiotherapy."
Michael Klein, president/CEO of Xoft, said that many studies presented at the ASCO symposium "support prior findings that much of the problem [of women not completing treatment] is based on inability to access therapy because of distance, fear, or difficulty with the logistics of getting to traditional radiation centers — likely even exacerbated by social and ethnic disparities. Many of these issues are addressed by electronic brachytherapy."
Xoft closed a Series E preferred stock financing in August, raising $25 million.