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· A “Boost” for Breast Cancer
· New Trial: Imaging for Staging Cervical Cancer
A “Boost” for Breast Cancer
Electron beam linear accelerator facilitates new treatment
The Mobetron electron-beam linear accelerator from IntraOp Medical Corp, Sunnyvale, Calif, has a capability that may be valuable to radiologists in light of recent clinical studies on breast cancer treatment: It can intraoperatively deliver a high dose of radiation, or “boost,” at the beginning of treatment, thereby improving patient outcomes and shortening the duration of therapy. The Mobetron Optimal Boost treatment method was recently validated in a 378-patient European trial, which proved the boost dose significantly reduced recurrence rates compared with historical matched pairs.
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| The Mobetron Optimal Boost treatment method was recently validated in a 378-patient European trial. |
“The Mobetron is used to provide intraoperative electron beam radiotherapy,” explained Donald Goer, PhD, chief scientist at IntraOp. “Its principal use has been for locally advanced and recurrent disease, but the Optimal Boost is a natural application for our machine. When you try to do a boost dose with external radiation, it depends on imaging technique, whether the tumor site is moving, whether it’s moved since surgery has happened. So giving that boost externally isn’t always a slam dunk. With intraoperative treatment, because the tumor site is exposed, you know precisely where you’re giving the boost. It’s optimal in terms of guidance and timing.”
Goer explains that in Europe, boost treatment, which is known there as “bio-boost,” is becoming very popular. “They say there’s a biological advantage,” Goer noted; hence the name. And the treatment is consistent with the newest trend in breast surgery: oncoplastic reconstruction.
“This is very popular in Europe,” Goer said. “At the time of the surgery they’re doing the oncoplastic reconstruction. The problem with doing it with external-beam boost is, when the surgeon gets in and reconstructs the breast, you don’t know where the cavity was. If you give the boost at the time of the lumpectomy, there’s no issue with where the cavity is. The surgeon can also do a breast reduction for the contralateral breast, so the woman emerges from surgery feeling more whole. The results are spectacular, both psychologically and in terms of costs. So it’s a win-win for everybody.” But, Goer notes, oncoplastic reconstruction is more difficult if the area’s set for irradiation a week later—that’s another reason electrons make such an ideal boost delivery option.
So far, only one small study of 50 patients has examined the long-term effects of bio-boost treatment. The median follow-up time for the group was 9 years, and during that period, only two patients experienced recurrences. “Those results indicate that this technique has real value in terms of local control and survival,” Goer said. “We just announced that we sold our first Mobetron to a German breast-only clinic; they were the first clinic in Germany to do breast-conserving techniques. Being able to provide this therapy at the time of the surgery is going to become the standard of care.”
One final application of external beam treatment for breast cancer is accelerated fractionation. “Sixteen fractions is now standard in Denmark, and it’s been demonstrated in Canada to be equally effective,” Goer said. “The idea is now to do the bio-boost with accelerated fractionation, so women can be done in 3 weeks, with no interference to chemotherapy.” Two European randomized trials are planned for next year to test accelerated fractionation on patients receiving bio-boost treatment.
Now, Goer said, all that remains is to persuade US radiation oncologists of the power of bio-boost treatment. “We have a lot of interest from surgeons because they are more aware of European research in this area than radiation oncologists,” he noted. “We need to get the word out. We think this is a great modality with a lot of potential.”
—Cat Vasko
New Trial: Imaging for Staging Cervical Cancer
New ACRIN trial underway
The American College of Radiology Imaging Network (ACRIN), Philadelphia, and the Gynecologic Oncology Group (GOG), Philadelphia, recently announced a new study designed to evaluate the ability of FDG-enhanced PET/CT and MRI with contrast agent Combidex to identify pelvic and abdominal lymph node metastases in patients with locoregionally advanced cervical cancer.
Recent research by study investigators suggests that the combination of FDG-PET/CT and Combidex MRI shows promise for detecting cancers that may currently go undiagnosed. Combidex, or ferumoxtran-10, consists of iron oxide nanoparticles; clinical trials have demonstrated that MRI combined with Combidex in staging cancer provides increased accuracy in the evaluation of lymph nodes. “Utility of Pre-operative PET-CT & USPIO MRI Prior to Primary Chemoradiation Therapy to Detect Retroperitoneal Lymph Node Metastasis in Patients with Loco- regionally Advanced Carcinoma of the Cervix” will continue to evaluate the contrast’s potential.
“Currently, we try to diagnose lymph node metastases by size,” explained the trial’s principal investigator, Mostafa Atri, MD, of the University Health Network and Mount Sinai Hospital at the University of Toronto, Canada. “This method has low specificity and low sensitivity. MRI with Combidex works differently. The contrast agent is absorbed by normal nodes, but not by the component of lymph node infiltrated by cancer. We see the cancer as defects in the lymph node. For PET, metastases appear as increased activity.”
Around 10 ACRIN-approved sites will collaborate with a GOG member institution to round up 325 participants over the next 3 years. All participants will undergo lymph node sampling to measure the accuracy of the imaging exams.
The GOG study chair is Michael Gold, MD, of the University of Oklahoma.
“Both imaging modalities can also be used with other cancers,” Atri noted. “Knowing the involvement of lymph nodes is important for the treatment of all cancer patients. If this study shows these modalities work for cervical cancer in a multicenter trial, it could lead to future research that would benefit many different cancer patients.”
The full protocol will be posted on the ACRIN Web site pending approval from the Cancer Therapy Evaluation Program. Further resources and more information about the trial are available online at www.acrin.org/6671_protocol.html.
—C. Vasko
