Radiotherapy in soft tissue sarcoma of the extremities

A phase Ib/II translational study of sunitinib with neoadjuvant radiotherapy in soft-tissue sarcoma

Background:

Preoperative radiotherapy (RT) is commonly used to treat localised soft-tissue sarcomas (STS). Hypoxia is an important determinant of radioresistance. Whether antiangiogenic therapy can ‘normalise' tumour vasculature, thereby improving oxygenation, remains unknown.

Methods:

Two cohorts were prospectively enrolled. Cohort A evaluated the implications of hypoxia in STS, using the hypoxic tracer ¹⁸F-azomycin arabinoside (FAZA-PET). In cohort B, sunitinib was added to preoperative RT in a dose-finding phase 1b/2 design.

Results:

In cohort A, 13 out of 23 tumours were hypoxic (FAZA-PET), correlating with metabolic activity (r²=0.85; P<0.001). Two-year progression-free (PFS) and overall (OS) survival were 61% (95% CI: 0.44–0.84) and 87% (95% CI: 0.74–1.00), respectively. Hypoxia was associated with radioresistance (P=0.012), higher local recurrence (Hazard ratio (HR): 10.2; P=0.02), PFS (HR: 8.4; P=0.02), and OS (HR: 41.4; P<0.04). In Cohort B, seven patients received sunitinib at dose level (DL): 0 (50 mg per day for 2 weeks before RT; 25 mg per day during RT) and two patients received DL: −1 (37.5 mg per day for entire period). Dose-limiting toxicities were observed in 4 out of 7 patients at DL 0 and 2 out of 2 patients at DL −1, resulting in premature study closure. Although there was no difference in PFS or OS, patients receiving sunitinib had higher local failure (HR: 8.1; P=0.004).

Conclusion:

In STS, hypoxia is associated with adverse outcomes. The combination of sunitinib with preoperative RT resulted in unacceptable toxicities, and higher local relapse rates.

Management of soft tissue sarcomas of the extremities

Soft tissue sarcomas are a diverse and rare group of neoplasms often found in the extremities. Treatment is best carried out in regional cancer centers by a multidisciplinary group with a common interest in these disorders. Treatment is usually surgical, with radiation used in select cases to try to reduce the risk of local recurrence. The role of chemotherapy is controversial, but it may be useful in patients at highest risk of developing metastatic disease. The development of newer forms of targeted systemic therapy and techniques to reduce the morbidity from local treatment to the extremity are areas of intense research interest.

New approach of bone marrow-derived mesenchymal stem cells and human amniotic epithelial cells applications in accelerating wound healing of irradiated albino rats

BACKGROUND AND OBJECTIVES

Irradiated wound healing is a highly complex and dynamic process. The latest technology making a huge difference in this process is stem cell therapy. The goal of this study was to evaluate the use of bone marrow-derived mesenchymal stem cells (BM-MSCs) or human amniotic epithelial cells (HAECs) in the healing of irradiated wounds.

METHODS AND RESULTS

Forty five male albino rats were subjected to whole body 6 gray gamma radiations. One day post irradiation, full-thickness incisional wound was created in the tibial skin. The rats were randomly equally divided into three groups. The incisions of the first group (gp I) were injected intra-dermally with saline before stitching and those of both the second (gp II) and the third groups (gp III) were intradermally injected with BM-MSCs and HAECs before stitching respectively. Animals were sacrificed after the third, seventh and fourteenth days postoperative. The healing process was assessed histopathologically. CXCL-5, SDF-1 and Transforming growth factor-beta 1 (TGF-β1) expression were also detected in biopsies from all wounds. Expression of TGF-β1 in gp I was more than the other groups leading to severe inflammation, deficient healed dermis and delayed reepithelialization. SDF-1 expression was high in gp II while CXCL-5 expression was high in gp III causing accelerated wound healing. BM-MSCs showed a great effect on the quality of the dermis, while superiority of the epithelium and its appendages were achieved in HAECs group.

CONCLUSIONS

Using BM-MSCs and HAECs could be used safely in case of irradiated wounds.

The significance of size change of soft tissue sarcoma during preoperative radiotherapy

AIM

To assess the significance of change in tumour size during preoperative radiotherapy in patients with soft tissue sarcoma (STS).

METHODS

A retrospective review of 91 cases with STS was performed. Inclusion criteria were localised extremity and truncal STS with measurable disease, older than 18 years, treated with preoperative radiotherapy and wide local excision, in the period between January 1966 and December 2005. Patients with head and neck STS, or who received neoadjuvant chemotherapy were excluded. A difference in excess of 10% of the greatest tumour diameter of the pre-radiotherapy and the post-radiotherapy MRI scans was considered as change in tumour size.

RESULTS

Increase in tumour size was noted in 28 patients (31%) (Group 1). No change or decrease in size was observed in 63 patients (Group 2). There were no significance differences in local control or overall survival rates between the 2 groups. The estimated overall actuarial local recurrence free, event-free and overall survival rates were 90.5%, 64.4%, 62.9% in Group 1, and 85.7%, 60.8%, 68.9% in Group 2 respectively.

CONCLUSION

Increase in tumour size during preoperative radiotherapy for soft tissue sarcoma does not seem to associate with inferior local tumour control or compromise survival. Lack of reduction in tumour size is not necessarily a sign of lack of response to preoperative radiotherapy.

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.

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.

Evaluation of clinical utility of BTC-2000 for measuring soft tissue fibrosis

PURPOSE

To evaluate whether mechanical tissue parameters, specifically laxity (in millimeters) and energy absorption (millimeters of mercury multiplied by millimeters) as measured by the BTC-2000, could discriminate levels of fibrosis severity among patients treated for extremity soft tissue sarcoma by surgery alone; preoperative radiotherapy (RT) and surgery; and surgery followed by postoperative RT.

METHODS AND MATERIALS

A total of 41 patients were treated for extremity soft tissue sarcoma by surgery alone (n = 11); preoperative RT (50 Gy in 2-Gy daily fractions) and surgery (n = 15); and surgery followed by postoperative RT (66 Gy in 2-Gy daily fractions; n = 15). Serial fibrosis measurements were evaluated at equal intervals from the midpoint of the surgical incision along the length of the incision. On the basis of the average of these measurements, differences among the three groups were analyzed using analysis of variance.

RESULTS

Pair-wise statistically significant differences were found among the three treatment groups for both laxity and energy absorption as determined by the average of all measurements. The treatment difference remained statistically significant even after adjusting for differences based on the untreated contralateral limb and anatomic site (p <0.001 and p = 0.002 for laxity and energy absorption, respectively).

CONCLUSION

The biomechanical tissue parameters of laxity and energy absorption discriminated fibrosis severity in patients treated with different RT doses. The BTC-2000 may provide a useful quantitative measure of soft tissue fibrosis.

Thallium-201 scintigraphy–a predictor of tumour necrosis in soft tissue sarcoma following preoperative radiotherapy?

AIM

Thallium-201 (Tl-201) scintigraphy in patients with malignant soft tissue tumours was evaluated to determine whether the images correlated with histological response to preoperative radiotherapy.

METHODS

We studied 54 patients, median age 32 (range 17-84) years, with non-metastatic, malignant soft tissue tumours diagnosed between 1996 and 2001. Thirty-eight patients had unoperated tumours and 16 patients had previous incomplete excisions. All patients received preoperative radiotherapy followed by surgery. No patient received chemotherapy as part of their initial management. Qualitative analyses of early phase (30 min) and late phase (4 h) Tl-201 scintigraphic images before and after preoperative radiotherapy were compared with the degree of tumour necrosis determined histologically.

RESULTS

In the previously unoperated group, all 38 patients had increased TL-201 uptake in the late phase of scanning prior to radiotherapy suggesting metabolically active tissue. In the previously excised group 11 patients had increased Tl-201 uptake in the late phase of scanning prior to radiotherapy. Following radiotherapy, patients with Tl-201 retention on late phase scans had a lower rate of necrosis than patients with minimal retention, p<0.0001. Following radiotherapy, 28 of 29 patients with minimal uptake on the late phase had 80% or more necrosis, while 24 of 25 patients with increased uptake on the late phase had less than 80% necrosis (p<0.0001). Patients with previously excised tumours who had thallium retention following radiotherapy demonstrated evidence of residual disease at surgery. All patients with incompletely excised tumours who had no thallium retention on late phase scanning after radiotherapy demonstrated no evidence of residual disease at surgery.

CONCLUSION

Thallium scintigraphy is a readily available investigative tool, which when used in conjunction with other imaging modalities in the assessment of primary and incompletely excised malignant soft tissue tumours, may predict histological tumour response to preoperative radiotherapy.

Wound complications following pre-operative radiotherapy for soft tissue sarcoma

AIMS

We analysed wound complications in 43 patients with soft tissue sarcoma who were treated with combined pre-operative radiotherapy and surgery.

METHODS

All patients received the same protocol of pre-operative radiotherapy at our institution.

RESULTS

Thirty-six (84%) patients developed acute skin toxicity following radiotherapy. After wide local excision, 15 patients required primary soft tissue reconstruction with vascularized muscle transfer and four patients underwent free skin flap to enable wound closure as part of their primary surgery. Nineteen patients (44%) developed post-operative wound complications including 10 (23%) patients who required an additional surgical procedure. Four (27%) patients developed flap necrosis in a group of 15 who underwent primary vascularized soft tissue transfer. All required a second vascularized muscular flap. One elderly patient, who had grade 3 acute radiation skin toxicity, had an arterial graft and total hip arthroplasty for a femoral artery aneurysm and an avascular necrosis of the hip, respectively. In our series, age (> or = 40 years) was the only impact factor influencing wound complication after surgery following radiotherapy (P=0.06).

CONCLUSIONS

Site of tumour, radiation field size, surgical resection volume, grade of acute radiation toxicity, co-morbidity, and smoking were not demonstrated to have predictive value in wound complication following pre-operative radiotherapy. Although previous papers suggested that vascularized soft tissue transfer could be useful reducing wound morbidity, our results could not confirm this.

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.