Effect of therapeutic radiation on wound healing

Proton Therapy for Mandibula Plate Phantom

Purpose: In this study, the required dose rates for optimal treatment of tumoral tissues when using proton therapy in the treatment of defective tumours seen in mandibles has been calculated. We aimed to protect the surrounding soft and hard tissues from unnecessary radiation as well as to prevent complications of radiation. Bragg curves of therapeutic energized protons for two different mandible (molar and premolar) plate phantoms were computed and compared with similar calculations in the literature. The results were found to be within acceptable deviation values. Methods: In this study, mandibular tooth plate phantoms were modelled for the molar and premolar areas and then a Monte Carlo simulation was used to calculate the Bragg curve, lateral straggle/range and recoil values of protons remaining in the therapeutic energy ranges. The mass and atomic densities of all the jawbone layers were selected and the effect of layer type and thickness on the Bragg curve, lateral straggle/range and the recoil were investigated. As protons move through different layers of density, lateral straggle and increases in the range were observed. A range of energies was used for the treatment of tumours at different depths in the mandible phantom. Results: Simulations revealed that as the cortical bone thickness increased, Bragg peak position decreased between 0.47–3.3%. An increase in the number of layers results in a decrease in the Bragg peak position. Finally, as the proton energy increased, the amplitude of the second peak and its effect on Bragg peak position decreased. Conclusion: These findings should guide the selection of appropriate energy levels in the treatment of tumour structures without damaging surrounding tissues.

Acute and Chronic Cutaneous Reactions to Ionizing Radiation Therapy

Ionizing radiation is an important treatment modality for a variety of malignant conditions. However, development of radiation-induced skin changes is a significant adverse effect of radiation therapy (RT). Cutaneous repercussions of RT vary considerably in severity, course, and prognosis. When they do occur, cutaneous changes to RT are commonly graded as acute, consequential-late, or chronic. Acute reactions can have severe sequelae that impact quality of life as well as cancer treatment. Thus, dermatologists should be informed about these adverse reactions, know how to assess their severity and be able to determine course of management. The majority of measures currently available to prevent these acute reactions are proper skin hygiene and topical steroids, which limit the severity and decrease symptoms. Once acute cutaneous reactions develop, they are treated according to their severity. Treatments are similar to those used in prevention, but incorporate wound care management that maintains a moist environment to hasten recovery. Chronic changes are a unique subset of adverse reactions to RT that may develop months to years following treatment. Chronic radiation dermatitis is often permanent, progressive, and potentially irreversible with substantial impact on quality of life. Here, we also review the etiology, clinical manifestations, pathogenesis, prevention, and management of late-stage cutaneous reactions to radiotherapy, including chronic radiation dermatitis and radiation-induced fibrosis.

Quantitative Evaluation of Local Control and Wound Healing Following Surgery and Stereotactic Spine Radiosurgery for Spine Tumors

OBJECTIVE

The present study evaluated the optimal measuring criteria to assess spinal tumor response to surgery followed by stereotactic spine radiosurgery (SRS) and reports the local control and wound complication rates following combined multimodality treatment.

METHODS AND MATERIALS

Prospectively collected patient information was retrospectively reviewed to identify patients treated with spine surgery followed by SRS. Tumor sizes and volumetric assessment were formally measured. Local control status was defined according to World Health Organization (WHO, bidimensional), RECIST (unidimensional), or volumetric size change. Statistical comparative assessments of tumor measurements were performed.

RESULTS

Twenty-two patients were eligible for evaluation after having undergone surgery followed by single-fraction SRS within a 2-month period. Seventeen had follow-up magnetic resonance imaging (MRI) with a mean patient follow-up of 12.59 months (range 3-36 months). None developed wound complication after radiation therapy (95% lower confidence bound 13%). Two patients had clinical recurrence while 15 of 17 achieved local control (88.3%). A test of marginal homogeneity for RECIST versus WHO was not statistically significant, P = 1.0 suggesting similar response classifications with both systems. Spearman correlations among 1) volumetric assessment, 2) bidimensional size, and 3) unidimensional size were significant for all groups (P < 0.05).

CONCLUSION

High local control rates can be achieved with surgery followed by SRS. Further, adjuvant SRS following spine tumor surgery delivers less radiation to the wound than conventional radiation and thus potentially reduces wound complications. Unidimensional, bidimensional, and volumetric tumor assessments demonstrate similar results. Hence the use of the simpler RECIST criteria is suitable and appropriate for evaluating the response to treatment after spine radiosurgery.

Influence of preoperative radiation field on postoperative leak rates in esophageal cancer patients after trimodality therapy

INTRODUCTION

Postoperative morbidities, such as anastomotic leaks, are common after trimodality therapy (chemoradiation followed by surgery) for esophageal cancer. We investigated for factors associated with an increased incidence of anastomotic leaks.

METHODS

Data from 285 esophageal cancer patients treated from 2000 to 2011 with trimodality therapy were analyzed. Anastomotic location relative to preoperative radiation field was assessed using postoperative computed tomographic imaging. Logistic regression was used to evaluate for factors associated with any or clinically relevant (CR) (≥ grade 2) leaks.

RESULTS

Overall anastomotic leak rate was 11% (31 of 285), and CR leak rate was 6% (17 of 285). Multivariable analysis identified body mass index (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.00-1.17; OR, 1.11, 95% CI, 1.01-1.22), three-field surgery (OR, 10.01; 95% CI, 3.83-26.21; OR, 4.83; 95% CI, 1.39-16.71), and within radiation field ("in-field") anastomosis (OR, 5.37; 95% CI, 2.21-13.04; OR, 8.63; 95% CI, 2.90-25.65) as independent predictors of both all grade and CR leaks, respectively. While patients with distal esophageal tumors and Ivor-Lewis surgery had the lowest incidence of all grade (6.5%) and CR leaks (4.2%), most of the leaks were associated with the anastomosis constructed within the field of radiation (in-field: 39% and 30% versus out-of-field: 2.6% and 1.0%, respectively, for total and CR leaks, p less than 0.0001, Fisher's exact test).

CONCLUSIONS

Esophagogastric anastomosis placed within the preoperative radiation field was a very strong predictor for anastomotic leaks in esophageal cancer patients treated with trimodality therapy, among other factors. Surgical planning should include a critical evaluation of the preoperative radiation fields to ensure proper anastomotic placement after chemoradiation therapy.

Impact of post-radiation biopsies on development of fistulae in patients with cervical cancer

OBJECTIVE

In the post-radiation patient, late vascular sequelae and fibrosis predispose women to poor tissue healing, such that small tissue injuries could theoretically evolve into much larger ones such as fistulae. We sought to determine if a correlation exists between invasive procedures such as post-treatment biopsies and the subsequent development of gynecologic fistulae.

METHODS

A retrospective review was performed evaluating all patients treated for cervical cancer at our institution between 1997 and 2010. Biopsies or pelvic surgeries were included if performed within the radiated field, and evaluated in a multivariate predictive model for development of gynecologic fistulae.

RESULTS

Out of 325 total patients, 27 patients with fistulae were identified (8.2%). 14 fistulae (51.9%) were considered toxicity-related, 6 (22.2%) resulted from primary disease, and 7 (25.9%) were attributable to recurrent disease. Eighty-nine patients underwent an invasive procedure (55 biopsies and 34 pelvic surgeries). Recurrent and/or residual cancer was found in 28 (31.5%) specimens, and of the 61 patients who underwent an invasive procedure and were not found to have evidence of recurrent disease, 9 (14.8%) subsequently developed a fistula at a median 3.08 months. An elevated dose of radiation to the rectum (OR 1.001 for dose >72 Gy, p=0.0005), advancing tumor stage (OR 5.38 for stage III, OR 10.47 for stage IV, p=0.0288), and a post-radiation biopsy (OR 5.27, p=0.013) were significantly associated with fistula development.

CONCLUSIONS

Performing a biopsy in an irradiated field is associated with a relatively low yield and significantly contributes to the risk for fistula development.

Complex wound-healing problems in neurosurgical patients: risk factors, grading and treatment strategy

BACKGROUND

Wound-healing problems in the neurosurgical patient can be particularly bothersome, owing to various specific risk factors involved. These may vary from simple wound dehiscence to complex multi-layer defects with cerebrospinal fluid (CSF) leakage and contamination. The latter is quite rare in practice and requires an individually titrated reconstruction strategy. The objective is to retrospectively analyze neurosurgical patients with complex, recalcitrant wound-healing problems we had treated in our department, attempt to develop a grading system based on the risk factors specific to our specialty and adapt a surgical reconstruction algorithm.

METHODS

During an 11-year period, 49 patients were identified to have had complex, recalcitrant wound-healing problems involving the cranial vault (n = 43) and the skull base (n = 6) that required an adapted surgical wound-management strategy. The etiologies of wound healing problems were aftermaths of surgical treatment of: (1) brain tumors (nine cases), (2) aneurysm clipping (ten cases), (3) trauma (27 patients), and (4) congenital malformations (three patients). Local rotational advancement flaps were performed in 18 patients and free microvascular tissue transfer was performed in 37 cases.

RESULTS

Major risk factors leading to recalcitrant wound healing problems in the presented group were: prolonged angiographic interventions (20%), ongoing chemotherapy or radiotherapy (47%), prolonged cortisone application (51%), CSF leak (76%) and, above all, multiple failed attempts at wound closure (94%). Stable long-term wound healing was achieved in all patients using vascularized tissue coverage. A ternary grading system was developed based on various risk factors in the presented cohort. Accordingly, the algorithm for reconstruction in neurosurgical patients was adapted.

CONCLUSIONS

Primary disease, treatment history, and distorted anatomical structures are major concerns in the management of complex wound-healing problems in neurosurgical patients. The higher the risk factors involved, the more complex is the surgical strategy. Free microvascular tissue transfer offers stable long-term results in recalcitrant cases. However, this may be indicated only in patients with a good prognosis of the underlying disease.

Wound healing following combined radiation and cetuximab therapy in head and neck cancer patients

OBJECTIVE

This study set out to determine if cetuximab treatment increases the risk of wound healing complications when combined with radiation therapy.

METHOD

We performed a retrospective chart review of head and neck cancer patients who received salvage neck dissections between 1999 and 2007, at two academic tertiary care centres. Complications from wound healing were compared between radiation and combined therapy groups.

RESULTS

A total of 35 patients received radiation (n=20) or combined radiation and cetuximab therapy (n=15) prior to neck dissection. The treatment groups were similar in regard to demographic and primary tumour-related characteristics. The time between treatment and salvage neck dissection did not differ between the radiation (3.9 months) and combination treatment (3.0 months) groups (p=0.15). Wound healing complications occurred in 13% (2/15) of the patients treated with radiation and cetuximab and there were no complications in patients who received radiation alone (p=0.20).

CONCLUSION

Cetuximab did not significantly increase the risk of post-surgical wound complications, although a higher absolute number of wound complications was observed in the group treated with cetuximab and radiation therapy, compared with the group treated with radiation alone.

CONFLICT OF INTEREST

This work was supported by a grant from the National Institute of Health (2T32 CA091078-06). One of the authors, JAB, is an occasional consultant and honoraria for ImClone and Bristol-Meyers Squibb.

Acellular dermal matrix seeded with autologous fibroblasts improves wound breaking strength in a rodent soft tissue damage model in neoadjuvant settings

Soft tissue defects following resectional surgery or trauma often result in deadspaces and require free or pedicled flaps. A programmed formation of filling tissue with enhanced biomechanical properties could be helpful. This study examined the effects on wound healing of acellular dermal matrix (ADM) seeded with autologous fibroblasts in a standardized rodent model. As pre- or postoperative radiotherapy is standard in many treatments of malignancies, we also investigated the effects of additional radiotherapy. Fischer rats were randomised and received a standardized unilateral soft tissue defect at the buttock. The defect was filled with ADM+fibroblasts or ADM alone. Controls received no filling. Either no radiation, adjuvant (postoperative) or neoadjuvant (preoperative) radiation was applied to the defect site. Six weeks later the defect volume was measured by MR-tomography. Wound breaking strength was examined by tensiometry according to German Industrial Standards. Filling of the defect side was significantly larger in ADM and ADM+fibroblast treated groups compared to the control group in all settings. Wound breaking strength in the unimodal setting was significantly improved in the ADM+fibroblasts group compared to the ADM group. In the neoadjuvant setting there was no significant difference between control and ADM group. However, the ADM+fibroblasts groups showed a significantly increased wound breaking strength compared to the control and the ADM-alone group. Seeded or unseeded ADM is able to fill deadspace in this rodent model in all settings. Implanting non-irradiated, vital, proliferating autologous fibroblasts on ADM results in significantly increased wound breaking strength.

Radiation-induced microenvironments--the molecular basis for free flap complications in the pre-irradiated field?

BACKGROUND AND PURPOSE

The effect of preoperative radio- or radiochemotherapy on the survival of free flaps used for head and neck reconstruction is reported in a contradictory way. Although there is a lot of knowledge on radiation-induced wound healing disorders from animal models there are no investigations on human patients so far. Our prospective study aimed at clarifying the effect of radiotherapy on clinically apparent free flap complications and on correlating them with radiation-induced extracellular matrix (ECM) remodeling.

MATERIALS AND METHODS

Healing of 114 free flaps was monitored in a prospective study and correlated with different anamnestic features, such as diabetes and radio- or radiochemotherapy using multivariate regression. During the operation connective tissue biopsies were harvested from the graft beds and analyzed for Transforming Growth Factor (TGF)-beta(1)-expression by means of Western blotting as well as Tissue Inhibitor of Matrix-Metallo-Proteinase (TIMP)-1 and Matrix-Metallo-Proteinase (MMP)-1 by immunohistochemistry.

RESULTS

History of radio- or radiochemotherapy was the only factor significantly predicting free flap complications. Radiochemotherapy resulted in a significant increase in TGF-beta(1)- and TIMP-1-expression, while MMP-1-expression was not significantly altered. Radiotherapy alone significantly increased TIMP-1-expression without detectable effects on TGF-beta(1) and MMP-1.

CONCLUSIONS

Radio- and radiochemotherapy alter graft bed ECM organization prior to surgery. This alteration impacts significantly on free flap survival in the pre-irradiated field.

TGF-beta and fibrosis in different organs - molecular pathway imprints

The action of transforming-growth-factor (TGF)-beta following inflammatory responses is characterized by increased production of extracellular matrix (ECM) components, as well as mesenchymal cell proliferation, migration, and accumulation. Thus, TGF-beta is important for the induction of fibrosis often associated with chronic phases of inflammatory diseases. This common feature of TGF-related pathologies is observed in many different organs. Therefore, in addition to the description of the common TGF-beta-pathway, this review focuses on TGF-beta-related pathogenetic effects in different pathologies/organs, i. e., arthritis, diabetic nephropathy, colitis/Crohn's disease, radiation-induced fibrosis, and myocarditis (including their similarities and dissimilarities). However, TGF-beta exhibits both exacerbating and ameliorating features, depending on the phase of disease and the site of action. Due to its central role in severe fibrotic diseases, TGF-beta nevertheless remains an attractive therapeutic target, if targeted locally and during the fibrotic phase of disease.

Performing nondiagnostic research biopsies in irradiated tissue: a review of scientific, clinical, and ethical considerations

PURPOSE

Recent development of drugs that target specific pathways in tumors has increased scientific interest in studying drug effects on tumor tissue. As a result, biopsies have become an important part of many early-phase clinical trials. Performing nondiagnostic tumor biopsies raises technical and ethical concerns mostly related to the use of a potentially harmful procedure with no potential benefit to the patient. This issue is complicated by uncertainty about whether performing biopsies in irradiated fields adds significant risk. This article reviews the clinical, scientific, and ethical considerations involved in performing nondiagnostic tumor biopsies in competent adults for research purposes, with a focus on biopsies performed in the setting of therapeutic irradiation.

METHODS

Clinical trials that performed biopsies during or within 4 months of the completion of radiotherapy were identified with a literature review.

RESULTS

Twenty-nine studies with 2,160 patients were identified. Sixteen of 29 studies reported adverse events (AEs) but did not report active evaluation for biopsy complications. Ten studies did not mention AEs within the study report. At least three studies actively evaluated patients for biopsy complications. Taking this into consideration, 17 (>1%) of 2,160 patients were reported to have biopsy complications, although reporting of AEs was suboptimal in most studies.

CONCLUSION

Limited data suggest that biopsies can be performed in irradiated tissues without clinically significant excess risk. Ongoing and future trials including nondiagnostic research biopsies should record and report AEs related to this procedure to provide additional data on safety and toxicity.

Model of radiation-impaired healing of a deep excisional wound

Despite many well-recognized benefits, administration of ionizing radiation before surgical resection of malignancies is associated with a high risk of wound-healing complications. Most animal models investigating techniques to improve wound healing use a superficial wound. The goal of this study was to develop a novel model of radiation-impaired healing using a deep excisional wound, which is closer to the clinical situation. In the first part of this study, female Lewis rats were exposed to 0, 12, 15, or 18 Gy single-fraction radiation to the buttocks. Three weeks later, deep wounds were created by excision of the gluteus maximus muscle. Irradiated wounds had a lower rate of healing of the surgically created defect than unirradiated wounds (p<0.001), but there was no significant difference between the different doses of radiation. Impaired healing was still evident at 12 weeks. The second part of this study investigated the ability of porcine small-intestinal submucosa (SIS) to improve healing in this animal model. At 6 weeks, wounds implanted with SIS showed improved healing at all doses of radiation compared with unimplanted irradiated wounds. However, higher doses of radiation were still associated with a lower rate of healing. SIS induced a cellular response that was not evident in defects that did not receive SIS, suggesting that SIS has the potential to stimulate repair. This reproducible model of radiation-impaired wound healing closely resembles the clinical setting. The results indicate that this model can be used to investigate new biomaterials as possible therapeutic agents to enhance wound healing.

Tolerance of Cutaneous or Mucosal Flaps Placed into a Radiation Therapy Field in Dogs

OBJECTIVE

To determine the clinical outcome and factors affecting cutaneous or mucosal flaps in dogs treated with radiation therapy (RT).

STUDY DESIGN

Longitudinal clinical study.

ANIMALS

Twenty-six client-owned dogs.

METHODS

Dogs entered in the study had a flapping procedure and RT as part of their treatment. The sequence of flapping and RT included: (1) planned preoperative RT, (2) postoperative RT, and (3) flapping as a salvage procedure for management of complications or local tumor recurrence after RT. Flap complications were defined as necrosis, local infection, dehiscence, and ulceration. The risk and severity of flap complication were analyzed independently.

RESULTS

Twenty (77%) dogs had a complication; 6 dogs required an additional flapping procedure; and 4 dogs had an unresolved complication. Flapping procedures performed to correct a complication, or failure of RT, had a significantly greater risk for complication; however, postoperative RT decreased the severity of complication. A dose per fraction of 4 Gy compared with 3 Gy was prognostic for increased severity of complications, whereas the head and neck location was prognostic for decreased severity of complication.

CONCLUSIONS

Although morbidity was substantial, cutaneous or mucosal flaps were used successfully in an RT field in 85% of the dogs. Flaps that were part of the planned therapy as opposed to those used to correct a complication or failure of RT had a better clinical outcome.

CLINICAL RELEVANCE

Cutaneous or mucosal flaps can be part of the treatment of dogs with tumor when adjuvant or neoadjuvant RT is to be used.

Primary multidisciplinary management of extremity soft tissue sarcomas

Soft tissue sarcomas (STS) are a rare and heterogeneous group of malignancies that most commonly present as large painless masses deep in the muscular compartments of the extremities. Investigation and treatment of these patients must be undertaken at a tertiary referral unit. Staging studies must include a high-quality magnetic resonance imaging (MRI) scan of the local site and a computed tomography (CT) scan of the chest to investigate for possible metastatic disease. Review of biopsy material must be undertaken by an experienced musculoskeletal pathologist. Currently, histologic diagnosis and grade are assigned to the tumor, but in tumors such as synovial sarcoma and Ewing's family of tumors, molecular evaluation is becoming crucial for diagnostic, prognostic, and therapeutic reasons. Surgical resection of sarcomas with negative surgical margins remains the mainstay of treatment. Surgical treatment alone is indicated for small superficial masses that are not adjacent to bone or neurovascular structures. However, in large deep masses where surgical margins are likely to be close in order to preserve important neurovascular structures and bone, combined treatment using surgical resection and radiation results in acceptable local control rates and reasonable patient function. It is incumbent on the management team to decide on timing of radiotherapy as a practice. This decision is based on several factors but potential complications must be taken into account. In this regard the long-term effects on normal tissues must be considered. Functional outcome has become an essential consideration when recommending treatment. If promising techniques become available to reduce the incidence of wound complications or to decrease the dose of radiation to normal tissue, preoperative radiation should be considered in light of its lower incidence of long-term effects that result in reduction in patient function.

Interference with transforming growth factor-beta/ Smad3 signaling results in accelerated healing of wounds in previously irradiated skin

Transforming growth factor (TGF)-beta regulates many aspects of wound repair including inflammation, chemotaxis, and deposition of extracellular matrix. We previously showed that epithelialization of incisional wounds is accelerated in mice null for Smad3, a key cytoplasmic mediator of TGF-beta signaling. Here, we investigated the effects of loss of Smad3 on healing of wounds in skin previously exposed to ionizing radiation, in which scarring fibrosis complicates healing. Cutaneous wounds made in Smad3-null mice 6 weeks after irradiation showed decreased wound widths, enhanced epithelialization, and reduced numbers of neutrophils and myofibroblasts compared to wounds in irradiated wild-type littermates. Differences in breaking strength of wild-type and Smad3-null wounds were not significant. As shown previously for neutrophils, chemotaxis of primary dermal fibroblasts to TGF-beta required Smad3, but differentiation of fibroblasts to myofibroblasts by TGF-beta was independent of Smad3. Previous irradiation-enhanced induction of connective tissue growth factor mRNA in wild-type, but not Smad3-null fibroblasts, suggested that this may contribute to the heightened scarring in irradiated wild-type skin as demonstrated by Picrosirius red staining. Overall, the data suggest that attenuation of Smad3 signaling might improve the healing of wounds in previously irradiated skin commensurate with an inhibition of fibrosis.

Therapeutic ultrasound and wound closure: lack of healing effect on x-ray irradiated wounds in murine skin

OBJECTIVE

To evaluate the efficacy of ultrasonography as a therapeutic agent in wound healing.

DESIGN

Randomized, controlled trial.

SETTING

University animal laboratory.

ANIMALS

Male BALB/c mice randomly allocated to 5 groups.

INTERVENTIONS

In group 1, mice were left untreated; in groups 2 through 5, a well-defined area on the dorsum was exposed to 20Gy x-ray irradiation. Seventy-two hours postirradiation, all mice were anesthetized by inhalation (isoflurane anesthetic) and a 7 x 7mm area wound made on the dorsum. All wounds were videotaped alongside a marker scale 3 times weekly until closure was complete. Mice in groups 4 and 5 were treated with pulsed therapeutic ultrasound for 5 minutes, 3 times weekly at 1 and 3MHz, respectively (intensity, 0.5W/cm(2)); mice in group 3 received placebo ultrasound. Subsequently, the area of each wound was measured from video by using an image analysis system.

MAIN OUTCOME MEASURE

Wound closure as a fraction of day zero.

RESULTS

Irradiation caused a significant (p < .01) delay in the rate of wound closure by day 11. However, neither placebo ultrasound nor treatment at 1 or 3MHz affected the closure rate.

CONCLUSION

These findings provide little evidence that 1 or 3MHz ultrasound applied to a radiation-impaired wound stimulates wound closure in mice.

Postsurgical wound management

Successful outcomes in cutaneous surgery depend on a variety of factors, including preoperative assessment of the patient's health and expectations, intraoperative skill and attention to detail, and managing the postoperative period. Once the procedure is complete, careful selection of dressings, provision of adequate analgesia, judicious management of complications and monitoring the phases of early maturation while providing patient education improve the likelihood of long-term patient and physician satisfaction.

The effects of intracoronary brachytherapy on the natural history of postangioplasty dissections

OBJECTIVES

The aim of this study was to determine the natural history of postangioplasty intravascular ultrasound (IVUS)-detected dissections and to assess the influence of intracoronary beta-radiation on dissection resolution.

BACKGROUND

Intracoronary radiotherapy is considered to impair exaggerated vessel healing. Conversely, excessive healing impairment may increase the risk of complications due to unhealed dissection. Alternatively, residual dissection may represent an innocent marker of adequate therapy.

METHODS

Immediate postangioplasty and six-month follow-up IVUS studies of 94 patients in the IVUS substudy of the MultiVitamins and Probucol (MVP) trial and 26 nonstented patients in the Beta Energy Restenosis Trial (BERT) were analyzed for the presence or absence of dissection.

RESULTS

Of the 28 patients with postangioplasty dissections in MVP, only one had evidence of residual dissection at six months (95% confidence interval [CI] for failure rate 0.2%; 20.2%). Conversely, 9 of 16 dissections had healed in BERT (95% CI for failure rate 30.6%; 79.2%) (p < 0.0002). Nevertheless, an index based on dissection arc and length demonstrated improvement in the irradiated patients. Irradiated patients with residual dissections showed significant increase in lumen area at six-months (5.10 +/- 0.98 to 7.11 +/- 2.61 mm2, p < 0.02) not noted when there was resolution of the dissection (6.03 +/- 2.38 to 6.36 +/- 3.33 mm2, p = NS). In both groups the external elastic membrane area was unchanged at follow-up.

CONCLUSIONS

Resolution appears to be the natural history of IVUS-detected dissections in most cases. Significant resolution of dissection occurs following intracoronary beta-radiation as reflected in reduced dissection index at six-months in these patients, although significant impairment of vessel wall healing was noted.

Intradermal injection of autologous dermal fibroblasts improves wound healing in irradiated skin

BACKGROUND

Despite its well-recognized benefits in the management of several solid tumors, the use of radiotherapy prior to surgery is associated with a high incidence of significant surgical wound healing complications. Radiation-induced damage to dermal fibroblasts has been proposed as an important cause. We hypothesized that the introduction of normal, unirradiated fibroblasts into previously irradiated skin would enhance healing of the subsequent surgical wound.

MATERIALS AND METHODS

Four groups of wounds were examined in female Wistar rats: (1) unirradiated skin (n = 10), (2) irradiated skin injected with tissue culture medium alone (n = 17), (3) irradiated skin injected with autologous dermal fibroblasts (n = 17), and (4) irradiated skin injected with irradiated autologous dermal fibroblasts (n = 7). Wounds were evaluated biomechanically and histologically.

RESULTS

The biomechanical values of breaking load, ultimate tensile strength, elastic modulus, and toughness were significantly greater in the irradiated wounds injected with fibroblasts than those injected with medium only. These cell-injected wounds did not perform as well biomechanically as those in unirradiated skin. Irradiating the cells prior to injection resulted in biomechanical results no better than those in medium-injected wounds.

CONCLUSIONS

These results demonstrate that injection of normal, unirradiated fibroblasts significantly improves healing of the irradiated surgical wound. These cells are likely better able to respond to the proliferative, migratory, and synthetic demands of the wound healing environment, as injection of irradiated cells has an equivalent effect on healing as injection of medium alone.

Wound healing following radiation therapy: a review

Radiation therapy may interrupt normal wound healing mechanisms. Changes in vasculature, effects on fibroblasts, and varying levels of regulatory growth factors result in the potential for altered wound healing whether radiation is given before or after surgery. Surgical factors, such as incision size, as well as radiation parameters, including dose and fractionation, are important considerations in developing overall treatment plans. Experience suggests that certain practical measures may diminish the risk of morbidity, and investigations are ongoing.