Home

Cover Story

Table of Contents

E-Newsletter

Article Archive

Editorial Calendar

Datebook

Writers' Guidelines

Orgs/Links

Opinion Polls

Reprints

Forum

July 31, 2006

Complicated Question
By Meghan A.T.B. Reese
Radiology Today
Vol. 7 No. 15 P. 18

A study in the International Journal of Radiation Oncology*Biology*Physics reported a high incidence of persistent fluid buildup in a 38-patient study of balloon brachytherapy treatment for breast cancer. The next question is, “What does that mean to patients?”

Some complications are more serious than others. The recently reported high incidence of seroma (fluid retention) in balloon brachytherapy patients shouldn’t derail an effective partial breast radiation therapy option, according to both the researcher who reported high seroma rates and the company that owns the technology.

A study published in the June 1 issue of the International Journal of Radiation Oncology*Biology*Physics, the official journal of the American Society for Therapeutic Radiology and Oncology (ASTRO), reported that 76% of patients receiving accelerated partial breast radiation therapy using a balloon brachytherapy system postlumpectomy for breast cancer developed seroma in the breast.

The researchers studied patients who had a MammoSite balloon brachytherapy catheter inserted during lumpectomy surgery to remove a cancerous tumor from their breast at Tufts-New England Medical Center in Boston and Rhode Island Hospital in Providence.

The MammoSite device is a small, soft balloon attached to a thin catheter that fits inside the lumpectomy cavity. A small radioactive source is inserted through the catheter into the balloon and radiation is delivered to the area of the breast where cancer is most likely to recur. Patients sometimes prefer this “one-stop-shop” as it allows them to get back to their families, jobs, and normal lives much faster than ongoing radiation therapy. With a 97% effective rate, according to the MammoSite Web site, this option raises the question of whether the fluid buildup, called “an annoyance” by Suzanne B. Evans, MD, MPH, lead author of the study and a radiation oncology resident at Tufts-New England Medical Center, is a fair trade-off for a simpler course of treatment.

The concern with seroma is that it can require aspiration or make monitoring the breast and tumor site by physical exam more difficult due to thickening of the excised area and decreased sensitivity. According to the study, the participants were followed for an average of 17 months. Of the 38 patients, 76.3% of them developed seroma in their breast and 68.4% had persistence beyond six months.

Common Complication
“Seroma is not infrequent after surgery, but it typically resolves itself within a few weeks to a month. However, we were seeing patients with seroma in the breast more than a year later,” Evans says.

Exactly what the high seroma incidence means isn’t clear.

“Is it 76% that is symptomatic? No, that’s not what the Tufts paper showed. The vast majority of those women were not symptomatic. It’s not a problem in terms of mammography follow-up,” says Ellen Sheets, MD, chief medical officer and senior vice president at Cytyc Corporation, which owns MammoSite. “They were looking to find seromas. Their instance of seroma is 76%. They were really looking, so it doesn’t surprise me they found so many. We view this as an interesting data set but nothing too unusual. If you look at MammoSite in general, it doesn’t increase your chances of symptomatic seromas over anybody else who is radiated. So we’re not sure why ASTRO came out with the [press] release [announcing the study].”

MammoSite also contends that seroma occurs naturally during the healing process, making the occurrence not as alarming as perhaps is being portrayed. The company has no plans to recommend changing the FDA-approved treatment. “I don’t think it’s one-sided, but I think it’s been misconstrued for something that it’s not,” Sheets says. “Up to 40% of women with lumpectomies will have a seroma for some period of time after the surgery. You certainly wouldn’t recommend stopping lumpectomies.”

Also, it is not just the MammoSite procedure that has an incidence of seroma. Interstitial radiation therapy—brachytherapy that involves “seeds” of radiation inserted through needles into the specific area—and 3-D conformal radiation therapy also have occurrence of seroma. “The same thing happens after partial breast with the interstitial, the MammoSite catheter, [and] 3-D conformal [radiation therapy],” Sheets says.

But seroma lasting more than six months is unusual in the case of 3-D conformal radiation and interstitial brachytherapy, according to the Tufts researchers.

Small Study
Sheets also points out that the study was conducted with only a series of 38 patients. “Given the overall landscape of the size of the study, 38 patients is not a lot,” she says. “You can go again and have 38 patients with none. You can have another 38 patients with one. It’s not a statistically relevant sample size to make a decision about if seroma rates are increasing significantly.”

MammoSite has its own data bank registry of 1,400 patients. “In that [the MammoSite] bank, under 9% complained of seroma. In large patient populations, using it in everyday care, 1,400 patients compared to 38, this is basically not a significant problem,” Sheets says.

One unanswered question about the balloon therapy is whether delaying catheter insertion to some time after the lumpectomy surgery, possibly allowing the body to begin the healing process, will result in lower seroma formation rates.

“If you wait a period of time and then put the MammoSite catheter in, when you put it in, you are going to drain whatever residual seroma is there that day because you are opening the cavity up and the fluid is just going to come out naturally,” Sheets says. “Putting the balloon in at the time of surgery, which is what the study was pointing to, the chance of seroma building up around that balloon, since you are not manipulating that cavity as much as if you were putting in the MammoSite at a distant time, you have to control for the fact that drainage of the seroma is occurring at different points in time. They didn’t take that into account in the study, so you can’t talk about what the optimal placement is. There’s no real data and their study doesn’t represent real data in that regard either.”

Evans notes that partial breast radiation therapy is not new and it’s the time frame that draws attention among patients and clinicians. She doesn’t think the Tufts study answers the seroma question, just raises it. She agrees that right now there is not much data on how patients will react and what the occurrence of seroma will be if the post-op waiting time to perform the MammoSite procedure was extended.

More Research Needed
“The truth is I don’t think MammoSite is a bad treatment. I think it is a potentially excellent treatment option,” Evans says. “We look forward to other studies in which the device is placed postoperatively to determine whether this lowers the rate of seroma formation.”

However, she adds, “if other institutions are seeing what we are seeing, where nearly two thirds have persistent seroma, then I think maybe some of the other techniques may be better.”

Regardless of the method, Sheets believes, there will be occurrence of seroma. “There will be an instance of seroma if you just do a lumpectomy and don’t do any radiation afterwards,” she says. “There will be some small percentage of women who will have persistent seroma for long periods of time just from that technique of surgical excision. If you use whole breast radiation, external radiation—which was the standard until accelerated [treatment] came on the market—those women will have persistent seroma just because the radiation itself. Radiation causes scarring. So they will react a little more strongly.”

Sheets doesn’t think the technique is the issue but that delivering radiation more intensely to the area of the excision increases scarring around the seroma.

Balloon brachytherapy is currently being studied to see whether it is as effective as external beam radiation after lumpectomy at keeping breast cancer from reoccurring. However, Evans contends that it could be related to the distant separation of the cavity walls by the balloon catheter in the immediate postoperative period, as rates of persistent seroma are lower with other brachytherapy techniques that also involved giving radiation intensely to the area of excision.

“It is still effective, but there are other options,” Evans says. “Interstitial is the most proven. 3-D [conformal radiation therapy] is the most convenient for patients and costs generally 60% to 70% less.”

Although Evans says the MammoSite technique could prove as effective as the interstitial brachytherapy treatment, patients often opt for the balloon catheter approach because the interstitial method involves up to 20 catheter needles. “Interstitial has sort of a cringe factor,” Evans says.

Time will tell how much of a clinical issue the seroma Tufts reported actually proves to raise. Like all complications, it’s better to be overcautious than overlook a problem. In this case, the potential problem is seroma’s possible interference with ongoing monitoring that could delay diagnosing recurrence. But at this point, no one knows what it means. Both Evans and Sheets agree that more trials and studies are necessary to address the issue.

— Meghan A.T.B. Reese is the assistant editor of Radiology Today.