How a new surgical implant helps radiologists identify tumor site for breast cancer follow-up exams
Advances in radiology technology now allow us to view breast tissue in more detail than ever before. Digital computing and information processing have made it possible to better enhance and interpret images. Breast cancer treatment is also progressing.
But until quite recently, innovations in breast cancer surgery and radiation therapy sometimes made it more difficult for the radiologist to perform follow-up exams. This article describes how a new surgical implant has now improved radiologists’ ability to track the tumor site years after a lumpectomy.
Challenges of Pinpointing Cancer Site
When we read follow-up images after lumpectomy, it’s essential to identify the site where the tumor was excised. One key point of the exam, after all, is to determine whether the cancer has recurred. Pinpointing the site is crucial because 75%-80% of recurrences take place near the original excision.1
Even with state-of-the-art imaging devices, surgery and radiotherapy can make it difficult to properly visualize the tumor site. They also hamper our assessment in other ways. For instance, scar tissue from the patient’s surgery and/or radiation therapy can obscure the site or even look like a returning cancer when it’s not.
3D Surgical Implant Advantages
Recently a new technology has emerged that addresses these challenges. Published research and several earlier reports show this novel device, a three-dimensional surgical implant (BioZorb®, Focal Therapeutics, Inc.), addresses these problems in both obvious and surprising ways.
The implant is a three-dimensional framework with six permanent titanium clips affixed to it. The breast surgeon sutures it right to the tumor site while performing a lumpectomy. The device can be easily seen on all contemporary imaging equipment, can be distinguished from bodily structures, and does not interfere with visualization. When it’s used, there’s no question about where the tumor site is.
The implant is made of a bioabsorbable material. The patient’s body will absorb it gradually until the device disappears in a year or more. The clips remain behind to mark the site for follow-up exams. Because the clips are uniquely shaped, the radiologist can easily distinguish them from biopsy clips.
To understand the other ways the implant is useful in our field, let’s start by going back to the scar tissue problem. Why does scar tissue form so extensively after some breast cancer surgeries? One reason is that radiation treatment planners are often forced to compute an overly large target volume when they do a boost at the end of the course of radiotherapy.
Targeting too much tissue during the boost phase can lead to more healthy tissue being damaged and the formation of more scar tissue. Why would radiation planners increase those risks? Because they, too, are sometimes uncertain where the tumor site is and want to make sure the site receives the proper dosing.
Planners live with this uncertainty because the conventional methods for identifying and boosting the tumor bed can yield ambiguous information. Seroma is often used as a target. But seroma caused by surgical incisions can also form far from the site, making it an unreliable indicator.
Alternatively, planners may use individual surgical clips as a guide. But surgeons often place clips to outline the entire resection, not the tumor bed within that area. The clips can also migrate during the post-operative healing process, and are sometimes confused with clips placed during surgery to control bleeding. So like seroma, clips can’t be trusted to accurately define the tumor bed.
Before the 3-D implant was available, the passage of time could also make the radiologist’s job more difficult. The longer the time between the original cancer surgery and the follow-up exam, the more likely it was that post-surgical changes in the breast could obscure the site.
These uncertainties are avoided when the implant is used because of the stable, reliable target it provides. That creates downstream benefits for patients and radiologists. For instance, boost treatment volumes can be smaller because the tumor site’s location is obvious when the patient is imaged. In research published in the World Journal of Surgery that I co-authored, 108 patients who were implanted with the device were studied. Treatment volumes were significantly reduced, which had the added benefit of making more women eligible for hypofractionated radiation therapy. This accelerated regimen is more convenient for patients and saved an estimated 25% in costs per person.2
Clinical experience has also demonstrated to me that only minimal scar tissue forms in patients who had the device implanted during their cancer surgery. Besides making it easier to visualize the tumor site, this is an indication that patients with the device can receive radiation therapy without the collateral damage to healthy tissue that other patients commonly suffer. As noted in the World Journal of Surgery article, the implant also provides a scaffold during post operative healing. This may be a factor in the minimal scarring and improved cosmetic outcomes that we’ve observed with the device after lumpectomy and breast reconstruction.
Finally, the implant appears to be a useful complement to oncoplastic surgery (OPS). While OPS improves cosmesis, it often involves extensive tissue rearrangement that can obscure visualization of the tumor site. The implant puts that concern to rest. It also helps replace some of volume loss that is created by a tumor excision.
The implant has been employed clinically since 2012, and there is newly published three-year patient data on its use. While caution is always warranted with any relatively new technology, the early research and clinical reports have been favorable.
- Kuerer HM, Julian TB, Strom EA, et al. Accelerated partial breast irradiation after conservative surgery for breast cancer. Ann Surg. 2004; 239(3): 338–351.
- Cross MJ, Lebovic GS, Ross J, Jones S, Smith S, Harms S. Impact of a novel bioabsorbable implant on radiation treatment planning for breast cancer. World J Surg. 2016. doi:10.1007/s00268-016-3711-y.