Our survey was conducted in four countries because there are no English or German published guidance on AFG in the head and neck to guide the treating teams. Most of our responses came from Plastic surgeons (95.5%), only two Otorhinolaryngologists completed our questionnaire. This response mismatch does not correlate with the count of active surgeons in the fields. There are 1328 active colleagues in Plastic surgery listed in UK and 1498 in Germany, UK counts 1916 ENT-surgeons, whereas Germany lists 2981 active colleagues in ENT (50-52). Reasonably we assume a broader use of AFG in Plastic surgery.
Most colleagues who participated in our survey (46,6%) state a ten to fifty times a year use of AFG and 14 percent stated an AFG-use of more than fifty times a year. The frequency of usage of AFG is not yet addressed in the literature. Where the indications have expanded beyond physical ‘contouring and space-filling’ to regenerative applications, we expect an increase of frequency of this application in use soon (2, 9, 12).
Although aesthetic applications of fat grafting in the head and neck seem to be more prominent (84% of respondents), a significant body of our survey respondents use autologous fat in the post-cancer treatment setting (62%). In our opinion, this correlates with the fact, that in recent decades AFG is being used increasingly. Responsible for that is the development of modern liposuction techniques in the 1980s by Illouz (2, 3), further Coleman provided a comprehensive description of techniques in the 1990s (6, 7). While fat grafting first gathered prominence in the aesthetic area (24), and a subsequent study showed it had a favourable complication profile compared to synthetic filler materials (25, 26), in recent years the scientific basis of the regenerative effects of fat grafting is progressing (6, 7).
HNC represents three percent of all malignant neoplasms, HNSCC is responsible for 90 percent of these cases (14). The resulting impairments of craniofacial cancer therapy, surgical reconstruction and radiotherapy make AFG a very promising and useful tool to deal with scars, irregularities and radiodermatitis and chronic radiation-induced fibrosis (32).
Due to harvesting and processing in AFG, the majority use syringe aspiration with a fine needle/cannula 1mm or greater (53%), and Vacuum aspiration with low pressure (34%). This correlates with a necessary low negative pressure level in aspiration and lower shear stress for the tissue. The perception seems to be, the higher the negative pressure level of liposuction, the higher the level of shear stress to the adipose tissue, reducing fat graft survival. (6, 29, 53)
Nearly half of our colleagues process their harvested tissue by centrifugation (46.5%), and the remainder (54%) had variable practices like sedimentation (16%) or pure graft (8%). Only two colleagues use mesh washing techniques. Tuin et al discovered no superior processing technique could be identified based on clinical outcome (35). The lower count of used washing techniques, in our opinion, may be because mesh washing techniques are labour intensive and are linked with a higher loss of graft material in the process, compared to the easy to use and fast centrifugation.
Nearly half of our survey participants do not discuss elevated cancer risk. On the other hand, only 31 percent stated knowledge of studies dealing with cancer recurrence following AFG. Moreover, most respondents have never confidently experienced cancer recurrence or newly developed cancer in a previously ablated region, following AFG. In several mastectomy studies, fat grafting and ASCs have not been shown to drive cancer growth in clinical reality, several studies with big cohorts showed no evidence for an elevation in oncological risk in AFG (40-42). Further, studies found no significant evidence for clinically relevant elevations in tumour size, proliferation, histologic grade or metastasis in AFG breast reconstruction. Most of the current studies dealing with the oncologic risk of AFG refer to breast cancer, further longitudinal shared data sets would be desirable to evaluate a possible pro-oncologic behaviour of AFG in the face, head and neck.
In conclusion, currently, there are no evidence-based studies which would authorize a valid recommendation due to pro-oncological risk of AFG in treated HNC tumour sites. There is a good case to suspect a different behaviour of ASCs in breast cancer cells versus HNSCC. Perhaps, we shouldn’t consider discussing this complex area of oncogenesis with patients as there is no elevated risk from what we know. However, the bulk of data is for breast carcinoma which is a different disease to HNSCC, and different tumours could conceivably interact in a different way to ASCs.