From OncoLog, April 2014, Vol. 59, No. 4
New Fat Grafting Technique Improves Aesthetic Outcomes Following Head and Neck Reconstructive Surgery
By Zach BohannanA new fat grafting technique is enabling reconstructive surgeons to maximize aesthetic outcomes following major reconstruction for head and neck cancer treatment–related defects.
Because head and neck cancer resections can be extensive, can involve many structures, and may be followed by radiation or other secondary therapies, reconstructive surgery for head and neck cancer–related defects historically has limited aesthetic benefits and is mostly concerned with functional restoration.
Roman Skoracki, M.D., and Matthew Hanasono, M.D., both associate professors in the Department of Plastic Surgery at The University of Texas MD Anderson Cancer Center, are helping pioneer the use of fat cell isolation and injection to improve the quality and appearance of reconstructed tissue for head and neck cancer patients. “We can perform functional reconstructions very well here, but this new grafting technique allows us to refine the aesthetic qualities of the reconstructions,” Dr. Skoracki said.
The procedure is currently used in some institutions to smooth the skin after breast reconstruction, but MD Anderson is among the first to use the technique in facial reconstruction following major cancer resections.
New hope for an old idea
Autologous fat transplants are traditionally small, to ensure an adequate blood supply for the fatty tissue, and often include nonfat tissue (such as skin), which may adversely affect aesthetic outcomes or limit the grafts’ usefulness in many reconstructions. High-volume fat transplants often fail because much of their volume is either lost to resorption or converted into scar tissue as a result of inadequate revascularization, which is needed to deliver oxygen and nutrients to each cell for survival. In fact, large autologous fat transplants sometimes form cysts that must be drained or surgically removed.
In the new approach to fat grafting, fat is first harvested by liposuction, using specialized cannulas, from a distant region of the body and subjected to centrifugation to quickly isolate the adipose tissue from liquid fat and blood. Then, many small amounts of the purified fat cells are injected into the target area. These multiple small transplants are arranged in a matrix over the target area, and this arrangement helps maintain the blood supply to each fat graft while still covering a relatively large area. These matrices of small grafts allow surgeons to precisely control the tissue thickness and aesthetics of the final result.
These fat cell grafting techniques may contribute to tissue improvement effects beyond aesthetics. Although these tissue improvement effects have not been fully characterized, Dr. Hanasono said, “The areas with the transplanted fat seem to be softer and more pliable than areas without the transplanted fat.” Dr. Skoracki added, “Sometimes, for patients with poor tissue quality as a result of radiation or other damage, we can take a gradual approach in which the first fat graft procedure improves suppleness and flexibility and then subsequent procedures help fill out the reconstruction.”
Use in head and neck reconstructions
For head and neck cancer–related reconstructions, this fat grafting procedure is usually a touch-up procedure performed well after primary cancer treatment and reconstruction have been completed. Dr. Hanasono said, “This is really a post-treatment procedure that we use when the patient is stable and the wound area is relatively safe—6 months to several years after the cancer has been cured. We always consult the primary oncologist as well to ensure that oncologic outcomes are not compromised.”
The speed and simplicity of these new fat grafts make them attractive to patients who are not satisfied with their existing reconstruction. Dr. Hanasono said, “It’s mostly an outpatient procedure, so we can bring previous patients in and perform touch-ups relatively easily.”
Most patients who have undergone head or neck reconstructive surgeries are eligible for this type of fat grafting procedure. Exceptions include patients with minimal subcutaneous fat—for example, those who are elite athletes or who have cachexia. Little fat is needed for a successful graft, but very low body fat percentages make it difficult to harvest a sufficient volume of fat for grafting.
For head or neck reconstructions, 100 mL of fat is typically harvested, but after purification, the total volume is generally half that. This is still more than enough material for a successful procedure, and Drs. Skoracki and Hanasono said they usually inject about 40 mL of fat at a time when performing head or neck reconstructions.
One persistent issue for fat grafts is the possibility of resorption, even in these small transplants. The amount of fat that remains resident after a transplant varies and is at least partially dependent on the state of the surrounding skin. Dr. Skoracki said, “There is some variability to the persistence of the fat, especially in patients who have a lot of scarring or skin damage from radiation therapy. In such patients, much of the fat gets resorbed, but the transplant still seems to improve the skin quality in the area.”
Some clinicians hypothesize that fat grafting improves tissue texture because fat contains stem cells. Researchers have previously shown that fat does contain inactive stem cells, but the data remain inconclusive about whether fat grafting can somehow activate the stem cells. Although active stem cells may help to reverse some of the scarring caused by radiation and surgery, there is the hypothetical concern that the stem cells could also contribute to second cancers. However, only one laboratory study has suggested this possibility, and it was performed in mice. None of the clinical studies performed to date have found evidence of fat-derived second cancers. Nevertheless, the American Society of Plastic Surgeons recommends that surgeons exercise caution when transplanting autologous fat into patients with a high risk of second cancer. “We have very little evidence that this technique carries a risk of second cancer, but we do try to be cautious when working with patients who have higher second cancer risks,” Dr. Skoracki said.
Some researchers at MD Anderson and other institutions are working to refine the new fat grafting technique to improve its effectiveness for use in a variety of reconstructive procedures such as breast reconstruction after lumpectomies. The use of autologous fat transplants in such procedures has been limited because they require larger volumes of fat than does head or neck reconstruction. The need for larger fat volumes may make it difficult to obtain adequate fat for transplantation and increase the chance of resorption or scarring.
Some equipment manufacturers are trying to reduce the time and increase the yield of the centrifugation process, which may facilitate fat transplants to more substantial parts of the body or for larger reconstructions.
Even as surgeons strive to improve the technique, Dr. Hanasono said the procedure has made a profound difference for his patients. He said, “For us, this has been a game changer because we can go from good reconstruction to much better.”
For more information, contact Dr. Matthew Hanasono at 713-794-1247 or Dr. Roman Skoracki at 713-794-1247.