Peripheral neuropathies following experimental intraoperative radiation therapy (IORT)

Outcomes of surgical resection and intraoperative electron radiotherapy for patients with para-aortic recurrences of gastrointestinal and gynecologic malignancies

BACKGROUND

Para-aortic lymph node (PALN) metastases from primary pelvic malignancies are often treated with resection, but recurrence is common. We report toxicity and oncologic outcomes for patients with PALN metastases from gastrointestinal and gynecologic malignancies treated with resection and intraoperative electron radiotherapy (IORT).

METHODS

We retrospectively identified patients with recurrent PALN metastases who underwent resection with IORT. All patients were included in the local recurrence (LR) and toxicity analyses. Only patients with primary colorectal tumors were included in the survival analysis.

RESULTS

There were 26 patients with a median follow up of 10.4 months. The rate of para-aortic local control (LC) was 77% (20/26 patients) and the rate of any cancer recurrence was 58% (15/26 patients). Median time from surgery and IORT to any recurrence was 7 months. The LR rate for those with positive/close margins was 58% (7/12 patients) versus 7% (1/14 patients) for those with negative margins (p = 0.009). 15% (4/26 patients) developed surgical wound and/or infectious complications, 8% (2/26 patients) developed lower extremity edema, 8% (2/26 patients) experienced diarrhea, and 19% (5/26 patients) developed an acute kidney injury. There were no reported nerve injuries, bowel perforations, or bowel obstructions. For patients with primary colorectal tumors (n = 19), the median survival (OS) was 23 months.

CONCLUSIONS

We report favorable LC and acceptable toxicity for patients receiving surgical resection and IORT for a population that has historically poor outcomes. Our data show disease control rates similar to literature comparisons for patients with strong risk factors for LR, such as positive/close margins.

Clinical feasibility of combining intraoperative electron radiation therapy with minimally invasive surgery: a potential for electron-FLASH clinical development

BACKGROUND

Local cancer therapy by combining real-time surgical exploration and resection with delivery of a single dose of high-energy electron irradiation entails a very precise and effective local therapeutic approach. Integrating the benefits from minimally invasive surgical techniques with the very precise delivery of intraoperative electron irradiation results in an efficient combined modality therapy.

METHODS

Patients with locally advanced disease, who are candidates for laparoscopic and/or thoracoscopic surgery, received an integrated multimodal management. Preoperative treatment included induction chemotherapy and/or chemoradiation, followed by laparoscopic surgery and intraoperative electron radiation therapy.

RESULTS

In a period of 5 consecutive years, 125 rectal cancer patients were treated, of which 35% underwent a laparoscopic approach. We found no differences in cancer outcomes and tolerance between the open and laparoscopic groups. Two esophageal cancer patients were treated with IOeRT during thoracoscopic resection, with the resection specimens showing intense downstaging effects. Two oligo-recurrent prostatic cancer patients (isolated nodal progression) had a robotic-assisted surgical resection and post-lymphadenectomy electron boost on the vascular and lateral pelvic wall.

CONCLUSIONS

Minimally invasive and robotic-assisted surgery is feasible to combine with intraoperative electron radiation therapy and offers a new model explored with electron-FLASH beams.

Practice-oriented solutions integrating intraoperative electron irradiation and personalized proton therapy for recurrent or unresectable cancers: Proof of concept and potential for dual FLASH effect

Background

Oligo-recurrent disease has a consolidated evidence of long-term surviving patients due to the use of intense local cancer therapy. The latter combines real-time surgical exploration/resection with high-energy electron beam single dose of irradiation. This results in a very precise radiation dose deposit, which is an essential element of contemporary multidisciplinary individualized oncology.

Methods

Patient candidates to proton therapy were evaluated in Multidisciplinary Tumor Board to consider improved treatment options based on the institutional resources and expertise. Proton therapy was delivered by a synchrotron-based pencil beam scanning technology with energy levels from 70.2 to 228.7 MeV, whereas intraoperative electrons were generated in a miniaturized linear accelerator with dose rates ranging from 22 to 36 Gy/min (at Dmax) and energies from 6 to 12 MeV.

Results

In a period of 24 months, 327 patients were treated with proton therapy: 218 were adults, 97 had recurrent cancer, and 54 required re-irradiation. The specific radiation modalities selected in five cases included an integral strategy to optimize the local disease management by the combination of surgery, intraoperative electron boost, and external pencil beam proton therapy as components of the radiotherapy management. Recurrent cancer was present in four cases (cervix, sarcoma, melanoma, and rectum), and one patient had a primary unresectable locally advanced pancreatic adenocarcinoma. In re-irradiated patients (cervix and rectum), a tentative radical total dose was achieved by integrating beams of electrons (ranging from 10- to 20-Gy single dose) and protons (30 to 54-Gy Relative Biological Effectiveness (RBE), in 10-25 fractions).

Conclusions

Individual case solution strategies combining intraoperative electron radiation therapy and proton therapy for patients with oligo-recurrent or unresectable localized cancer are feasible. The potential of this combination can be clinically explored with electron and proton FLASH beams.

Brachial Plexus Tolerance to Single-Session SAbR in a Pig Model

PURPOSE

The single-session dose tolerance of the spinal nerves has been observed to be similar to that of the spinal cord in pigs, counter to the perception that peripheral nerves are more tolerant to radiation. This pilot study aims to obtain a first impression of the single-session dose-response of the brachial plexus using pigs as a model.

METHODS AND MATERIALS

Ten Yucatan minipigs underwent computed tomography and magnetic resonance imaging for treatment planning, followed by single-session stereotactic ablative radiotherapy. A 2.5-cm length of the left-sided brachial plexus cords was irradiated. Pigs were distributed in 3 groups with prescription doses of 16 (n = 3), 19 (n = 4), and 22 Gy (n = 3). Neurologic status was assessed by observation for changes in gait and electrodiagnostic examination. Histopathologic examination was performed with light microscopy of paraffin-embedded sections stained with Luxol fast blue/periodic acid-Schiff and Masson's trichrome.

RESULTS

Seven of the 10 pigs developed motor deficit to the front limb of the irradiated side, with a latency from 5 to 8 weeks after irradiation. Probit analysis of the maximum nerve dose yields an estimated ED₅₀ of 19.3 Gy for neurologic deficit, but the number of animals was insufficient to estimate 95% confidence intervals. No motor deficits were observed at a maximum dose of 17.6 Gy for any pig. Nerve conduction studies showed an absence of sensory response in all responders and absent or low motor response in most of the responders (71%). All symptomatic pigs showed histologic lesions to the left-sided plexus consistent with radiation-induced neuropathy.

CONCLUSIONS

The single-session ED₅₀ for symptomatic plexopathy in Yucatan minipigs after irradiation of a 2.5-cm length of the brachial plexus cords was determined to be 19.3 Gy. The dose-response curve overlaps that of the spinal nerves and the spinal cord in the same animal model. The relationship between the brachial plexus tolerance in pigs and humans is unknown, and caution is warranted when extrapolating for clinical use.

Emerging Translational Opportunities in Comparative Oncology With Companion Canine Cancers: Radiation Oncology

It is estimated that more than 6 million pet dogs are diagnosed with cancer annually in the USA. Both primary care and specialist veterinarians are frequently called upon to provide clinical care that improves the quality and/or quantity of life for affected animals. Because these cancers develop spontaneously in animals that often share the same environment as their owners, have intact immune systems and are of similar size to humans, and because the diagnostic tests and treatments for these cancers are similar to those used for management of human cancers, canine cancer provides an opportunity for research that simultaneously helps improve both canine and human health care. This is especially true in the field of radiation oncology, for which there is a rich and continually evolving history of learning from the careful study of pet dogs undergoing various forms of radiotherapy. The purpose of this review article is to inform readers of the potential utility and limitations of using dogs in that manner; the peer-reviewed literature will be critically reviewed, and current research efforts will be discussed. The article concludes with a look toward promising future directions and applications of this pet dog “model.”

Microneurosurgical treatment options in peripheral nerve compression syndromes after chemotherapy and radiation treatment

Chemotherapy-induced peripheral neuropathy and radiation-induced brachial plexopathy are extremely debilitating conditions which can occur after treatment of malignancy. Unfortunately, the diagnosis can be elusive, and this dilemma is further compounded by the lack of efficacious therapeutics to prevent the onset of neurotoxicity before initiating chemotherapy or radiation or to treat these sequelae after treatment. However, microsurgical nerve decompression can provide these patients with a viable option to treat this complication.

Orofacial Pain in Cancer: Part I—Mechanisms

The mechanisms involved, and possible treatment targets, in orofacial pain due to cancer are poorly understood. The aim of the first of this two-part series is to review the involved pathophysiological mechanisms and explore their possible roles in the orofacial region. However, there is a lack of relevant research in the trigeminal region, and we have therefore applied data accumulated from experiments on cancer pain mechanisms in rodent spinal models. In the second part, we review the clinical presentation of cancer-associated orofacial pain at various stages: initial diagnosis, during therapy (chemo-, radiotherapy, surgery), and in the post-therapy period. In the present article, we provide a brief outline of trigeminal functional neuro-anatomy and pain-modulatory pathways. Tissue destruction by invasive tumors (or metastases) induces inflammation and nerve damage, with attendant acute pain. In some cases, chronic pain, involving inflammatory and neuropathic mechanisms, may ensue. Distant, painful effects of tumors include paraneoplastic neuropathic syndromes and effects secondary to the release of factors by the tumor (growth factors, cytokines, and enzymes). Additionally, pain is frequent in cancer management protocols (surgery, chemotherapy, and radiotherapy). Understanding the mechanisms involved in cancer-related orofacial pain will enhance patient management.

Dose delivered to the lumbosacral plexus from high-dose-rate brachytherapy for cervical cancer

OBJECTIVE

To calculate dose delivered to the lumbosacral plexus (LSP) with cervical brachytherapy using 3-dimensional imaging, and to compare this with the position of the tandem in the pelvis using bony landmarks. We also report long-term LSP toxicity outcomes.

METHODS AND MATERIALS

Treatment planning images from 55 patients treated with tandem and ring brachytherapy from October 2009 through November 2012 were reviewed. The LSP was contoured on planning computed tomographic scans to calculate dose received. Lumbosacral plexus dose was studied as a function of tandem distance from the sacrum and pubic symphysis (STratio) measured on digitally reconstructed radiographs. Patient and implant characteristics were included as covariates on LSP dose. Clinical follow up on LSP toxicity was recorded.

RESULTS

Patients were prescribed 550 to 700 cGy using computed tomography-based imaged-guided brachytherapy for 4 to 5 fractions. The maximum dose to 2 cc (D2cc) of LSP ranged from 44 to 287 cGy per implant. The median D2cc was 118 cGy, corresponding to 18% of prescription dose. Patients with an STratio less than 0.33 (closer to the sacrum) and at least 0.33 had median LSP doses of 138 and 98 cGy, respectively. Lumbosacral plexus dose did not change significantly with body mass index, uterus position, or tumor stage. Two patients reported symptoms of peripheral neuropathy, with a median follow-up of 14.7 months.

CONCLUSIONS

The mean D2cc per fraction to the LSP is roughly 20% of the prescribed high dose-rate and varies with the position of the tandem from the sacrum. The dose threshold for radiation-induced neuropathy of the LSP remains undefined.

Use of botulinum toxin type A for the treatment of radiation therapy-induced myokymia and neuromyotonia in a dog

CASE DESCRIPTION A 5-year-old castrated male Maltese was evaluated for intermittent clinical signs of muscle cramping and abnormal movements of the skin of the right pelvic limb at the site where an infiltrative lipoma had twice been resected. After the second surgery, the surgical field was treated with radiation therapy (RT). The clinical signs developed approximately 14 months after completion of RT. CLINICAL FINDINGS When clinical signs were present, the right biceps femoris and semitendinosus muscles in the area that received RT were firm and had frequently visible contractions, and the skin overlying those muscles had episodic vermiform movements. Electromyography of those muscles revealed abnormal spontaneous activity with characteristics consistent with myokymic discharges and neuromyotonia. Magnetic resonance imaging of the affected leg revealed no evidence of tumor regrowth. The myokymia and neuromyotonia were considered secondary to RT. TREATMENT AND OUTCOME 4 U of Clostridium botulinum toxin type A (BoNT-A) neurotoxin complex was injected into the affected muscles at each of 6 sites twice during a 24-hour period (ie, 48 U of BoNT-A were administered). The clinical signs were completely resolved 10 days after BoNT-A treatment and were controlled by repeated BoNT-A treatment every 3 to 4 months for > 1 year. CLINICAL RELEVANCE To our knowledge, this is the first report of myokymia and neuromyotonia secondary to RT in a dog. For the dog of this report, injection of BoNT-A into the affected muscles was safe, effective, and easy to perform.

Direct effect of radiation on the peripheral nerve in a rat model

Radiation neuropathy is one of the severe complications of radiotherapy. Entrapment neuropathy, caused by surrounding soft tissue fibrosis induced by radiation, plays a key role in the onset of this neuropathy. Meanwhile, the pathophysiology of the direct effect of radiation on the peripheral nerve is not yet fully understood. The aim of this study is to investigate the direct effects of radiation on rat sciatic nerves that are isolated from surrounding soft tissue. In the radiation group (R group), only the exposed sciatic nerve was irradiated with 90 Gy X-radiation. In the sham group (S group), the surgical procedures were completed without radiation. The sciatic functional index (SFI) result demonstrated no statistical differences between the R group and S group. However, even though the surrounding soft tissue was not irradiated, the macroscopic and histological findings of the R group at 24 weeks after radiation showed scar formation around the radiated nerve. These findings on radiation neuropathy indicate that neurohumoral factors derived from the radiated nerve itself may cause fibrosis. The electromyographic and histological examination showed axonal degeneration in the R group. Furthermore, the axon diameter and axon packing density in the R group demonstrated the axonal degeneration, even though it was 0.5 cm more proximal to the radiated portion than the axon packing density in the S group. This appearance was assumed to be "dying-back" neuropathy. It is believed that this study is a first step toward identifying an accurate pathophysiology for intractable radiation-induced peripheral neuropathy.

Paralysis following stereotactic spinal irradiation in pigs suggests a tolerance constraint for single-session irradiation of the spinal nerve

BACKGROUND AND PURPOSE

Paralysis observed during a study of vertebral bone tolerance to single-session irradiation led to further study of the dose-related incidence of motor peripheral neuropathy.

MATERIALS AND METHODS

During a bone tolerance study, cervical spinal nerves of 15 minipigs received bilateral irradiation to levels C5-C8 distributed into three dose groups with mean maximum spinal nerve doses of 16.9 ± 0.3 Gy (n=5), 18.7 ± 0.5 Gy (n=5), and 24.3 ± 0.8 Gy (n=5). Changes developing in the gait of the group of pigs receiving a mean maximum dose of 24.3 Gy after 10-15 weeks led to the irradiation of two additional animals. They received mean maximum dose of 24.9 ± 0.2 Gy (n=2), targeted to the left spinal nerves of C5-C8. The followup period was one year. Histologic sections from spinal cords and available spinal nerves were evaluated. MR imaging was performed on pigs in the 24.9 Gy group.

RESULTS

No pig that received a maximum spinal nerve point dose ≤19.0 Gy experienced a change in gait while all pigs that received ≥24.1 Gy experienced paralysis. Extensive degeneration and fibrosis were observed in irradiated spinal nerves of the 24.9 Gy animals. All spinal cord sections were normal. Irradiated spinal nerve regions showed increased thickness and hypointensity on MR imaging.

CONCLUSION

The single-session tolerance dose of the cervical spinal nerves lies between 19.0 and 24.1 Gy for this model.

Intraoperative radiation therapy

Intraoperative radiation therapy (IORT) is the delivery of irradiation at the time of an operation. This is performed by different techniques including intraoperative electron beam techniques and high-dose rate brachytherapy. IORT is usually given in combination with external-beam radiation therapy with or without chemotherapy and surgical resection. IORT excludes part or all dose-limiting sensitive structures, thereby increasing the effective dose to the tumor bed (and therefore local control) without significantly increasing normal tissue morbidity. Despite best contemporary therapy, high rates of local failure occur in patients with locally advanced or recurrent rectal cancer, retroperitoneal sarcoma, select gynecologic cancers, and other malignancies. The addition of IORT to conventional treatment methods has improved local control as well as survival in many disease sites in both the primary and locally recurrent disease settings. More recently, there has been interest in the use of IORT as a technique of partial breast irradiation for women with early breast cancer. Given newer and lower cost treatment devices, the use of IORT in clinical practice will likely grow, with increasing integration into the treatment of nonconventional malignancies. Optimally, phase III randomized trials will be carried out to prove its efficacy in these disease sites.

intraoperative radiation therapy part 2. Clinical results

Intraoperative radiation therapy (IORT) has been used for over 30 years in Asia, Europe and America as a supplementary activity in the treatment of cancer patients with promising results. Modern IORT is carried out with electron beams (IOERT) produced by a linear accelerator generally used for external beam irradiation (EBRT) or a specialized mobile electron accelerator. HDR brachytherapy (HDR-IORT) has also been applied on selected locations. Retrospective analysis of clinical experiences in cancer sites such as operable pancreatic tumour, locally advanced/recurrent rectal cancer, head and neck carcinomas, sarcomas and cervical cancer are consistent with local tumour control promotion compared to similar clinical experiences without IORT. New emerging indications such as the treatment of breast cancer are presented. The IORT component of the therapeutical approach allows intensification of the total radiation dose without additional exposure of healthy tissues and improves dose-deposit homogeneity and precision. Results of the application of IORT on selected disease sites are presented with an analysis on future possibilities. To improve the methodology, clinical trials are required with multivariate analysis including patient, tumour and treatment characteristics, prospective evaluation of early and late toxicity, patterns of tumour recurrence and overall patient outcome.

Effects of External Beam Radiation in the Rat Tibial Nerve after Crush, Transection and Repair, or Nerve Isograft Paradigms

INTRODUCTION

In head and neck surgery, radiation therapy is often administered to an injured nerve. Previous studies have examined the effects of either preoperative or postoperative radiation on nerve regeneration in rodents. In these studies, histomorphometric analysis was performed up to 8 month postoperatively. Given the exceptional neuroregenerative capacity of rodents, significant differences in nerve regeneration may go undetected if nerves are evaluated at such distant postoperative time points. This study is designed with a more appropriate model and investigates the effects of radiation after three common nerve injury paradigms.

METHODS

Sixty-four Lewis rates were randomized to 8 groups corresponding to uninjured, tibial nerve crush, transection and repair, or reconstruction with isografts. Half of the animals in each of these paradigms (n = 8 per group) were treated with 10 Gy of external beam radiation to the site of nerve injury at 7 days postoperatively. On postoperative day 28, functional recovery and histomorphometric assessment was performed.

RESULTS

For a given paradigm of nerve injury, no significant differences in nerve fiber number, neural density, neural debris, or fiber width were noted between the control and radiated groups, and radiation did not affect functional recovery.

CONCLUSION

Radiation had no discernible effect on nerve regeneration or functional recovery in the rodent nerve injury models studied. All assessments were made at time points suitable for detecting differences in nerve regeneration between groups. These findings suggest that administration of radiation to fields containing injured peripheral nerve is unlikely to adversely affect functional outcomes.

Normal tissue tolerance to intraoperative radiotherapy

Much experimental evidence has been accumulated assessing the tolerance of various tissues to IORT, and much of the tolerance data have resulted from the use of canine models. Guidelines of IORT tissue tolerance established in experimental models have been used in the clinical application of IORT at numerous institutions. Although the radiotolerance of differing tissues can vary among species, sufficient clinical experience has accumulated to validate the canine tissue tolerance model as representative of human tissue responses to IORT. Cellular effects from radiation principally stem from direct damage to DNA, and thus proliferating tissues are among the most radiosensitive, with arrested or abnormal cell division. These tissues can manifest striking early toxicity, reflecting the rate of cell division that is affected by the radiation. Irradiation of nonproliferating or slowly proliferating tissues may show little or no early toxicity, but late effects can be manifested to considerable and varying degrees. In much of this late toxicity, pathologic changes develop from progressive ischemia, brought about by the gradual obliteration of small blood vessels. Irradiated endothelium often becomes replaced by a thickened fibrous layer, which, in small vessels, leads to occlusion and ischemic necrotic changes in the supplied tissue. In larger vessels, fibrosis can lead to wall weakening and aneurysmal dilatation, rupture, or thrombosis. The common denominator, then, of radiation damage to many tissues is related to vascular effects. Although the tolerance to IORT-induced toxicity can vary considerably among tissues, doses ranging to 25 Gy can generally be tolerated without significant toxicity. Vital areas where IORT dose must be carefully monitored include critical vasculature, gastrointestinal viscera, ureter, significant motor or sensory nerve trunks, and central nervous system structures. Higher doses can generally be delivered safely to anatomic areas at risk for tumor that are at a distance from sensitive organs or tissues. The general principle providing the rationale of IORT should always be practiced: maximize the radiation dose to the tumor and tumor-harboring tissues while minimizing dose exposure to surrounding normal tissues.

Intraoperative radiotherapy electron boost followed by moderate doses of external beam radiotherapy in resected soft-tissue sarcoma of the extremities

PURPOSE

To analyze the patterns of failure and the toxicity profile of intraoperative electron beam radiotherapy (IOERT) after resection of soft tissue sarcomas of the extremities (STS).

PATIENTS AND METHODS

Forty-five patients with extremity STS were treated with IOERT and moderate-dose postoperative radiotherapy (45-50 Gy). Twenty-six patients were treated for primary disease (PD) and 19 patients for an isolated recurrence (ILR). Tumor size was >5 cm (maximum diameter) in 36 patients (80%), and high-grade histology in PD patients was present in 14 patients (54%). In nine patients, IOERT was used alone, due to previous irradiation or patient refusal. Chemotherapy (neoadjuvant and/or adjuvant) was mainly given to high-grade tumors.

RESULTS

Nine patients relapsed in the extremity (20%), and 12 patients in distant sites (28%). Actuarial local control at 5 years was 88% for patients with negative/close margins and 57% for patients presenting positive margins (P=0.04). Five patients (11%) developed neuropathy associated with the treatment. Extremity preservation was achieved in 40 patients (88%). With a median follow-up of 93 months (range: 27-143 months) for the patients at risk, 25 patients remain alive (a 7-year actuarial survival rate of 75% for PD and 47% for ILR; P=0.01).

CONCLUSIONS

IOERT combined with moderate doses of external beam irradiation yields high local control and extremity preservation rates in resected extremity STS. Peripheral nerves in the IOERT field are dose-limiting structures requiring a dose compromise in the IOERT component to avoid severe neurological damage.

High-dose-rate intraoperative irradiation: current status and future directions

Intraoperative irradiation (IORT) refers to the delivery of a single high dose of radiation therapy at the time of surgery when the tumor bed can be precisely defined and adjacent normal tissue maximally protected. It can be effectively delivered using either electrons (IOERT) or photons produced from a high-dose-rate gamma emitting radioisotope (HDR-IORT) and has been explored primarily for locally advanced or recurrent tumors at high risk for local failure despite extensive resection and full dose external beam radiation. With coordinated multidisciplinary interaction, IORT can be integrated in a combined-modality setting without undue additional toxicity. The purpose of this review will be to summarize the growing HDR-IORT experience in the treatment of various cancers, to compare its efficacy and toxicity vis a vis the IOERT data, and to discuss future trials as well as new areas of potential application.

Successful treatment of intimal hyperplasia in renal arteries by endovascular brachytherapy

PURPOSE

The present study shows the possibility of preventing restenosis of renal arteries by endovascular brachytherapy.

METHODS AND MATERIALS

We present a patient suffering from rapid restenosis of both renal arteries with decreasing renal function. Percutaneous transluminal angioplasty (PTA) and stent implantation were unable to stop hypertension and to stabilize renal function. Both renal arteries and the right pole artery were treated by endovascular brachytherapy in one session.

RESULTS

Six months after intervention, intraarterial digital subtraction angiography (DSA) showed no evidence of recurrence, and the blood pressure remained normal without medical treatment.

CONCLUSION

Endovascular brachytherapy can help to prevent restenosis in renal arteries. It is possible to treat both renal arteries and one pole artery in one session without any disadvantage.

Long-term normal tissue effects of intraoperative electron radiation therapy (IOERT): late sequelae, tumor recurrence, and second malignancies

PURPOSE

To evaluate long-term survivors treated with intraoperative electron radiation therapy (IOERT) as a component, with particular emphasis on analyzing late normal tissue toxicity, second malignancies, and patterns of delayed tumor recurrence.

METHODS AND MATERIALS

From September 1984 to December 1991, 739 patients were treated with IOERT. One hundred ninety-five patients were alive at least 5 years after IOERT (26%). Patient information regarding late complications related symptoms, incidence of second tumors, and delayed relapses were analyzed. Normal tissue changes were categorized by a modified LENT/SOMA scale (Grade 0-1, Grade 2, and Grade 3-4). Risk of late toxicity was grouped by type and number of cancer treatment modalities employed in each patient: surgery + IOERT alone (17 patients, 9%); IOERT + external radiotherapy +/- chemosensibilization (90 patients, 46%); IOERT +/- external radiotherapy +/- neoadjuvant chemotherapy (+/- previous radiotherapy) (88 patients, 45%). Biologic effective doses (BED) were calculated for alpha/beta = 3.5 for late fibrosis.

RESULTS

With a mean follow-up time of the surviving patients of 94 months (range: 55-162 months), 99 patients (51%) had Grade 0-1 toxicity, 52 (27%) had Grade 2, and 44 patients (23%) presented Grade 3-4 late normal tissue complications. Risk groups by treatment intensity did correlate with severity of observed toxicity (p < 0.001). BED estimations did not correlate with late normal tissue damage. The tumor type with higher toxicity scores was bone sarcoma (28/46, 60%), in which the estimated BED = 100.5 Gy. Peripheral neuropathy was the dominant IOERT-specific toxicity present in 24 patients (12%). Second malignancies were identified in 8 patients (4%), none inside the IOERT field (3 questionable to be marginal to the external beam radiotherapy volume). In 36 patients (18%), recurrence of the originally treated tumor was detected, including 11 (7%) local relapses.

CONCLUSIONS

The incidence of late normal tissue complications (50%) and severity (23%) is significant in a cohort of patients surviving more the 5 years after IOERT. The understanding of the contribution of IOERT to late tissue damage requires specific analysis. Peripheral neuropathy is a characteristic finding in IOERT trials. Second malignancies inside the IOERT field were not identified during the study period. The risk of recurrences, including local failures, requires an intensive follow-up of long-term survivors from IOERT trials.

Results and complications of surgery combined with intra-operative radiation therapy for the treatment of locally advanced or recurrent cancers in the pelvis

Intra-operative radiation therapy (IORT) can benefit patients with pelvic tumors by delivering a high dose of radiation with precise delineation of tumor bed and maximal protection of surrounding normal tissues. The IORT experience has been particularly promising for locally advanced primary or recurrent rectal cancers in which a gross total resection is achieved. However, its potential benefit must be weighed against added toxicity. The main dose-limiting toxicity of pelvic IORT is peripheral neuropathy and ureteral stenosis. We will review the techniques for optimal IORT delivery, the results of the major studies investigating IORT treatment of rectal cancer, and the pelvic complications associated with combining surgery and IORT. A team of surgeons and radiation oncologists providing close multidisciplinary coordination is essential to integrate IORT with combined modality regimens in a safe and effective manner.

Brachytherapy in the treatment of colorectal malignancies

By precisely delivering a single, high dose fraction of intraoperative radiation under direct visualization while excluding surrounding normal dose-limiting tissues, IORT has improved the therapeutic ratio of tumor control to morbidity. Both IOERT and HDR-IORT represent effective means of delivering this therapy, and either may be chosen with equal confidence, depending upon the facilities available, physician preference, and the clinical situation. The extraordinary efforts often required in the management of these highly selected patients is justified by the improvement achieved in the enhanced local control rates and increased cure rates. Preoperative chemoradiation therapy followed by gross total resection and IORT affords the patient the highest likelihood of local control and survival. The importance of aggressive surgery in achieving gross total resection with pathologically negative margins is reflected by the dramatic correlation reported between margin status and local control. The high complication rate associated with this multidisciplinary therapy is, no doubt, multifactorial and may be attributed to the advanced disease state at presentation and the intensive multidisciplinary treatments administered. In an effort to eradicate disease and prolong survival, many consider these elevated complication rates acceptable, particularly in light of the complexity of these cases, as well as the morbidity and mortality associated with persistent disease in the pelvis.

Effects of intraoperative irradiation (IORT) and intraoperative hyperthermia (IOHT) on canine sciatic nerve: histopathological and morphometric studies

PURPOSE/OBJECTIVE

Peripheral neuropathies have emerged as the major dose-limiting complication reported after intraoperative radiation therapy (IORT). The combination of IORT with hyperthermia may further increase the risk of peripheral nerve injury. The objective of this study was to evaluate histopathological and histomorphometric changes in the sciatic nerve of dogs, after IORT with or without hyperthermia treatment.

METHODS AND MATERIALS

Young adult beagle dogs were randomized into five groups of 3-5 dogs each to receive IORT doses of 16, 20, 24, 28, or 32 Gy. Six groups of 4-5 dogs each received IORT doses of 12, 16, 20, 24, or 28 Gy simultaneously with 44 degrees C of intraoperative hyperthermia (IOHT) for 60 min. One group of dogs acted as hyperthermia-alone controls. Two years after the treatment, dogs were euthanized, and histopathological and morphometric analyses were performed.

RESULTS

Qualitative histological analysis showed prominent changes such as focal necrosis, mineralization, fibrosis, and severe fiber loss in dogs which received combined treatment. Histomorphometric results showed a significantly higher decrease in axon and myelin and small blood vessels, with a corresponding increase in connective tissue in dogs receiving IORT plus hyperthermia treatment. The effective dose for 50% of nerve fiber loss (ED50) in dogs exposed to IORT only was 25.3 Gy. The ED50 for nerve fiber loss in dogs exposed to IORT combined with IOHT was 14.8 Gy. The thermal enhancement ratio (TER) was 1.7.

CONCLUSION

The probability of developing peripheral neuropathies in a large animal model is higher when IORT is combined with IOHT, when compared to IORT application alone. To minimize the risk of peripheral neuropathy, clinical treatment protocols for the combination of IORT and hyperthermia should not assume a thermal enhancement ratio (TER) to be lower than 1.5.

Brachytherapy with iridium-192 HDR to prevent from restenosis in peripheral arteries. An update

The use of stents does not appreciably improve restenosis (usually resulting from intimal hyperplasia) as compared to percutaneous transluminal angioplasty (PTA) alone. The development of small-caliber probes for afterloading therapy in the biliary tract allowed us to use these for therapy in the vascular system. Using a special 9 F catheter, exact measurement of the length of the stented vascular segment and of the insertion length of the afterloading probe could be reproducibly performed. We used a Nucletron (Micro) Selectron HDR planning system version 10.10 for exact calculation, monitoring, and control of the afterloading procedure. Our source was iridium 192 (10 Ci) with a diameter of 1.1 mm. The program controls and monitors the insertion and removal of the iridium probe from the source into the special catheter through to the tip, and monitors the irradiation duration. The exposure time was around 200 seconds for a surface dose of 12 Gy. To date, a total of 40 patients have been treated with endovascular afterloading. All patients suffered from clinically relevant reocclusions or restenoses in stented vascular segments of the superficial femoral artery following successful PTA or laser treatment, within 6 to 8 months after the last therapy. In all patients it was possible to perform re-PTA treatment without remaining residual stenoses in the stented region. The additional time required as compared to PTA alone was approximately 45 minutes with most of this time spending for transportation between the cath lab and afterloading room. The follow-up period of the 40 patients ranged from 4 months to 71/2 years. In 33 patients, there was no deterioration of the clinical stage and no restenosis. One patient suffered from an acute thrombosis approximately 3 months after stent implantation, another patient had a stenosis 3 cm above the stented vascular segment 12 months after irradiation treatment. Follow-up examinations have revealed no evidence of nerve lesions following irradiation therapy. The tissue surrounding the artery showed no change following irradiation therapy, either in the CT, color-coded Doppler, endovascular ultrasonic scan or MRI. No complaints of discomfort were reported during or after irradiation. With the exceptions mentioned above, there was no evidence of any complications.

[Late effects of intraoperative radiotherapy]

Several experimental studies on animals have yielded to the tolerance single doses for different critical organs. Anatomical alterations are located essentially in the intima of the arteries with oedema, histio-lymphoplasmocytoïd infiltration in a first time leading to arterial obstructions and necrosis after the 6th week. These radiation injuries are related to the IORT dose, the target volume and the time interval between the IORT treatment and the apparition of the side-effects. Moreover, some radiation induced sarcomas have been observed in animals after the 5th year which suggest that the follow-up period after IORT must be prolonged enough to appreciate the exact complications rate of IORT. If we exclude the usual post-operative complications, the complications observed in human IORT treatments may be either early side effects on small bowel, esophagus or late effects: peripheral neuropathies, osseous complications, and microvascular obstructions. A more precise clinical description and an improved knowledge of the relationships with different treatment characteristics should allow us to prevent more efficiently the IORT complications.

Dose-response tolerance of the visual pathways and cranial nerves of the cavernous sinus to stereotactic radiosurgery

As the number of patients treated with stereotactic radiosurgery increases, it becomes particularly important to define with precision adverse effects on distinct structures of the nervous system.

OBJECT

This study was designed to assess the dose-response tolerance of the visual pathways and cranial nerves after exposure of the cavernous sinus to radiation.

METHODS

A total of 66 sites in the visual system and 210 cranial nerves of the middle cranial fossa were investigated in 50 patients who had undergone gamma knife treatment for benign skull base tumors. The mean follow-up period was 40 months (range 24-60 months). Follow-up examinations consisted of neurological, neuroradiological, and neuroophthalmological evaluations. The actuarial incidence of optic neuropathy was zero for patients who received a radiation dose of less than 10 Gy, 26.7% for patients receiving a dose in the range of 10 to less than 15 Gy, and 77.8% for those who received doses of 15 Gy or more (p < 0.0001). Previously impaired vision improved in 25.8% and was unchanged in 51.5% of patients. No sign of neuropathy was seen in patients whose cranial nerves of the cavernous sinus received radiation doses of between 5 and 30 Gy. Because tumor control appeared to have been achieved in 98% of the patients, the deterioration in visual function cannot be attributed to tumor progression.

CONCLUSIONS

The structures of the visual pathways (the optic nerve, chiasm, and tract) exhibit a much higher sensitivity to single-fraction radiation than other cranial nerves, and their particular dose-response characteristics can be defined. In contrast, the oculomotor and trigeminal nerves have a much higher dose tolerance.

Locally advanced primary colorectal cancer: intraoperative electron and external beam irradiation +/- 5-FU

PURPOSE

For locally advanced primary colorectal cancer, our institution has combined intraoperative electron irradiation (IOERT) with external beam irradiation (EBRT) +/- 5-fluorouracil (5-FU) and surgical resection. Disease control and survival were compared with the current IOERT and prior non-IOERT regimens.

METHODS AND MATERIALS

From April 1981 through August 1995, 61 patients received an IOERT dose of 10-20 Gy, usually combined with 45-55 Gy of fractionated EBRT; 56 had minimum follow-up of 18 months. The amount of residual disease remaining at IOERT after exploration and maximal resection in the 56 patients was gross in 16, < or = microscopic in 39, and unresected in 1.

RESULTS

Survival (SR) and disease control were analyzed as a function of potential prognostic factors. Factors that achieved statistical significance for improved overall survival included treatment sequence of preop EBRT + 5-FU (vs. postoperative EBRT + 5-FU, p = 0.003) and < or = microscopic residual disease after maximal resection (vs. gross residual, p = 0.005). Those that appeared to favorably impact disease-free survival included EBRT + 5-FU (vs. EBRT alone, p = 0.01), < or = microscopic residual (vs. gross, p = 0.0014), and colon site of primary (vs. rectum, p = 0.009). Failures within an irradiation field have occurred in 4 of 16 patients (25%) who presented with gross residual after partial resection vs. 2 of 39 (5%) with < or = microscopic residual after gross total resection (p = 0.01). The significant prognostic factors for a decrease in distant metastases were the same as for disease-free SR with respective p-values of 0.013 (EBRT + 5-FU), 0.008 (microscopic residual), and 0.03 (colon primary). The current data suggests a relationship between IOERT dose and incidence of Grade 2 or 3 neuropathy (< or = 12.5 Gy--1 of 29 or 3%, > or = 15 Gy--6 of 26 or 23%, p = 0.03).

CONCLUSIONS

Both overall survival and disease control appear to be improved with the addition of IOERT to standard treatment. More routine use of systemic therapy is indicated as a component of IOERT containing treatment regimens because the incidence of distant metastases was 50% of patients at risk.

Differential dose delivery using a nondocking applicator for intraoperative radiation therapy

PURPOSE

Although treatment of a field within a field to deliver a boost dose is quite common with external photon beam radiation therapy, the same is not always true with electron beam radiation or in intraoperative radiation therapy (IORT). The purpose of this work is to report the results and details of a new technique developed to treat a field within a field in intraoperative radiation therapy.

METHODS AND MATERIALS

This technique makes use of the nondocking IORT system currently used at our institution. Treatment is given in two segments: the large field is first treated by using standard circular lucite cones; the second dose segment is delivered using a new circular brass cone designed to fit concentrically within the large lucite cone.

RESULTS

Central axis depth dose, surface dose, output factors, and two-dimensional beam profiles have been measured for a 7 cm inner diameter (i.d.) flat lucite cone and 3.8 and 5 cm i.d. flat brass cones for electron beam energies ranging from 4-22 MeV. For different clinical target volumes, summed dose distributions differentially weighted in both energy and dose are presented.

CONCLUSIONS

A simple technique for delivering differential dose in intraoperative radiation therapy is presented. The technique provides a method for escalating dose to higher values for a defined target volume.

A phase I pilot study of pelvic radiation and alpha-2A interferon in patients with locally advanced or recurrent rectal cancer

PURPOSE

The purpose of this pilot study was to determine the maximum tolerated dose of alpha-2a interferon given by subcutaneous injection and combined with high dose pelvic radiation for locally advanced or recurrent rectal cancer.

METHODS AND MATERIALS

In this Phase I pilot study, patients with locally advanced, unresectable, or recurrent rectal cancer with or without distant metastases received external beam pelvic radiotherapy over 5 to 6 weeks combined with escalating doses of alpha-2a interferon. Interferon was escalated in increments of 3 million units for each patient cohort, starting at 3 million units subcutaneously 3 days weekly during pelvic radiation. Radiotherapy consisted of 44 Gy (2 Gy fractions) to the pelvis followed by a boost of 6 Gy or 16 Gy to gross pelvic tumor, depending on the presence or absence of small bowel in the boost field, respectively. Between 1991 and 1993, 10 patients were treated on this study, five with locally advanced and five with locally recurrent rectal cancer.

RESULTS

At 6 million units of interferon, Grade 3 (WHO criteria) toxicities were as follows: diarrhea (one), leukopenia (one), and neutropenia (one). One patient died of a massive GI bleed at this dose level. Death was not felt to be treatment related. The maximum tolerated dose of interferon was 3 million units three times weekly with radiation. Three patients had unusual complications at 4, 6, and 6 months possibly related to treatment. The first had a right distal ureteric stricture with a right urinoma. The second had a sudden left foot drop that has remained stable. The third had sudden onset of bilateral lower extremity paraplegia with spontaneous resolution.

CONCLUSIONS

The maximally tolerated dose of interferon alpha-2a given three times weekly during pelvic radiation was 3 million units based on acute side effects. Nevertheless, even at this dose level there were three unusual subacute complications possibly related to treatment. Caution is advised when combining interferon alpha-2a with high dose pelvic radiation, especially in patients with predisposing conditions (such as diabetes) for radiotherapy complications.

Intraoperative electron and external beam irradiation with or without 5-fluorouracil and maximum surgical resection for previously unirradiated, locally recurrent colorectal cancer

PURPOSE/OBJECTIVE

1) Disease control and survival will be evaluated for treatment regimens containing intraoperative electron irradiation (IOERT) for locally recurrent, previously unirradiated colorectal cancers. 2) Various prognostic factors will be evaluated to determine whether they have an impact on disease control or survival.

MATERIALS AND METHODS

From April 1981 through August 1995, 123 patients with previously unirradiated locally recurrent colorectal cancers received IOERT at our institution, usually as a supplement to external beam irradiation (EBRT) and maximum resection. All received EBRT with or without concomitant 5-fluorouracil-based chemotherapy. Forty-five Gy in 25 fractions was given to the tumor or tumor bed plus 3-cm to 5-cm margins in 121 of 123 patients and a boost of 5.4 to 9 Gy in 3 to 5 fractions to the tumor plus 2-cm margins. Maximum resection was performed before or after EBRT. IOERT doses ranged from 10 to 20 Gy in 119 of 123 patients, with dose dependent on resection margins (130 fields in 123 patients). Maintenance chemotherapy was given to only two patients.

RESULTS

Disease relapse and survival were evaluated. Central failure (within the IOERT field) was documented in 13 of 123 patients (11 percent) with a five-year actuarial rate of 26 percent. Local relapse (in EBRT field) occurred in 24 patients (20 percent); five-year rate was 37 percent. Distant metastases occurred in 66 patients (54 percent); five-year rate was 72 percent. Median survival was 28 months, with overall survival at two, three, and five years of 62, 39, and 20 percent, respectively. Tolerance data suggest a relationship between IOERT dose and incidence of Grade 2 or 3 neuropathy (< or = 12.5 Gy, 2 of 29 or 7 percent; > or = 15 Gy, 19 of 101 or 19 percent; P = 0.12). Survival and disease control were analyzed as a function of potential prognostic factors. None of the prognostic factors had a significant impact on disease control or survival. Although there was a trend for reduction in local relapse rates with gross total vs. partial resection, this neither achieved statistical significance nor translated into improved survival. Patients with gross residual disease after maximum resection had three-year and five-year survival rates of 36 and 18 percent, respectively, which paralleled results for patients with gross total resection at 41 and 24 percent, respectively.

CONCLUSION

Encouraging trends for improved local control with or without survival exist in separate locally recurrent colorectal IOERT analyses from our institution and other institutions. Therefore, continued evaluation of IOERT approaches seems warranted. Disease control within the IOERT and external fields is decreased when the surgeon is unable to accomplish a gross total resection. Therefore, it is reasonable to consistently add 5-fluorouracil or other dose modifiers during EBRT and to evaluate the use of dose modifiers in conjunction with IOERT (sensitizers and hyperthermia). In view of high systemic failure rates of > 50 percent in patients with locally recurrent disease, more routine use of systemic therapy is indicated as a component of IOERT-containing treatment regimens (use existent chemotherapy and/or develop effective immunotherapy and gene transfer therapy). Even with locally recurrent lesions, the aggressive multimodality approaches including IOERT have resulted in improved local control and long-term survival rates of 20 percent vs. an expected 5 percent with conventional techniques.

Intraoperative radiotherapy for pancreatic carcinoma. Experimental and clinical studies

Intraoperative radiotherapy (IORT) is an innovative treatment approach that has been tested in several Phase I-II studies and small Phase III trials in patients with resectable and unresectable pancreatic cancer. The technical approach and dose guidelines for adjacent normal tissues have been established in a series of experiments using a large animal (canine) model. This article reviews the experimental and clinical studies of IORT in cancer of the pancreas.

Retroperitoneal soft tissue sarcomas: a pilot study of intraoperative radiation therapy

This pilot study was conducted to evaluate the feasibility and tolerance of a multimodal therapy of retroperitoneal soft tissue sarcoma (STS), including intraoperative radiation therapy (IORT). Nineteen patients (14 primarily treated patients and 5 treated for a recurrent tumor) were included. Surgery included a complete resection (14), a partial resection (2), and no resection (2). The median IORT dose was 17 Gy. Thirteen patients also received an external radiation therapy (ERT). Nine patients received chemotherapy. There was no postoperative mortality. Immediate postoperative complications occurred in four patients (21%). Delayed complications occurred in six patients, including one lethal iliac artery disruption. With a median follow-up of 17 months, the 2-year disease-free survival rate was 60%, and the 2-year actuarial local control rate was 76%. A multimodality approach of treatment, including IORT and ERT and eventually chemotherapy, appears feasible in patients with retroperitoneal STS. However, the treatment-related morbidity appeared relatively high in this study.

Recurrences of rectal cancers: results of a multimodal approach with intraoperative radiation therapy. French Group of IORT. Intraoperative Radiation Therapy

PURPOSE

Prognosis of recurrent rectal cancer remains poor, mainly because of the difficulties of achieving a satisfactory local control. Intraoperative radiation therapy (IORT) allows for the delivery of a complementary single dose to the tumor residues or to the tumor bed and could be useful jn a multimodal treatment. In an attempt to evaluate this interest, a retrospective analysis of patients treated with IORT in six French hospitals has been performed.

METHODS AND MATERIALS

Data have been collected in 73 patients (41 men), with a mean age of 62 years, treated with IORT. Initial rectal tumors were large (mean diameter: 45 mm), partially or totally fixed to the contiguous structures in 39%, and with nodal involvement in 50% of the cases. Initial surgery had been a sphincter-sparing surgery in 67%; external radiation therapy had been delivered in 52%, and a chemotherapy had been given in 10% of the patients. Recurrences were isolated (without metastases) in 86%, and were posterior or posterolateral in 55% of the cases. Surgery allowed for a complete macroscopical resection in 57%, a partial resection with gross residual disease in 29%, and no resection in 14% of the recurrences. Intraoperative radiation therapy was delivered in a dose of 10 to 25 Gy (mean 18.5) through localizators of a mean diameter of 75 mm (60 to 110). External radiation therapy, either preoperative or postoperatively was given to 30 patients without prior radiation therapy. Ten patients received additional chemotherapy with 5-fluorouracil.

RESULTS

Four postoperative deaths occurred. Postoperative morbidity occurred in 16 patients and some complications were probably related to the IORT procedure. Four long-term complications were observed. Overall actuarial survival occurred in 72.4% of the patients at 1 year, in 44.6% at 2 years, and in 30.6% at 3 years. Twenty-one local failures have been observed. Actuarial local control occurred in 71.3% of the patients at 1 year, 47.7% at 2 years, and 31.3% at 3 years.

CONCLUSION

Intraoperative radiation therapy is a complementary treatment for recurrences of rectal cancer. It provides encouraging results, particularly in some selected situations, when patients have not previously been treated with external radiation therapy. Further studies of multimodal treatments are necessary.

Effects of intraoperative irradiation and intraoperative hyperthermia on canine sciatic nerve: neurologic and electrophysiologic study

PURPOSE

Late radiation injury to peripheral nerve may be the limiting factor in the clinical application of intraoperative radiation therapy (IORT). The combination of IORT with intraoperative hyperthermia (IOHT) raises specific concerns regarding the effects on certain normal tissues such as peripheral nerve, which might be included in the treatment field. The objective of this study was to compare the effect of IORT alone to the effect of IORT combined with IOHT on peripheral nerve in normal beagle dogs.

METHODS AND MATERIALS

Young adult beagle dogs were randomized into five groups of three to five dogs each to receive IORT doses of 16, 20, 24, 28, or 32 Gy to 5 cm of surgically exposed right sciatic nerve using 6 MeV electrons and six groups of four to five dogs each received IORT doses of 0, 12,16, 20, 24, or 28 Gy simultaneously with 44 degrees C of IOHT for 60 min. IOHT was performed using a water circulating hyperthermia device with a multichannel thermometry system on the surgically exposed sciatic nerve. Neurologic and electrophysiologic examinations were done before and monthly after treatment for 24 months. Electrophysiologic studies included electromyographic (EMG) examinations of motor function, as well as motor nerve conduction velocities studies.

RESULTS

Two years after treatment, the effective dose for 50% complication (ED50) for limb paresis in dogs exposed to IORT only was 22 Gy. The ED50 for paresis in dogs exposed to IORT combined with IOHT was 15 Gy. The thermal enhancement ratio (TER) was 1.5. Electrophysiologic studies showed more prominent changes such as EMG abnormalities, decrease in conduction velocity and amplitude of the action potential, and complete conduction block in dogs that received the combination of IORT and IOHT. The latency to development of peripheral neuropathies was shorter for dogs exposed to the combined treatment.

CONCLUSION

The probability of developing peripheral neuropathies in a large animal model was higher for IORT combined with IOHT, than for IORT alone. The dose required to produce the same level of late radiation injury to the sciatic nerve was reduced by a factor of 1.5 (TER) if IORT was combined with 44 degrees C of IOHT for 60 min.

Intraoperative radiation therapy and Mohs micrographic surgery on an outpatient basis

BACKGROUND

Intraoperative radiation therapy (IORT) is used to deliver therapeutic doses of radiation to a surgically exposed tumor or tumor bed while minimizing the radiation dose to adjacent normal tissue. It is traditionally given with the patient under general anesthesia.

OBJECTIVE

To report a case of a recurrent squamous cell carcinoma treated with Mohs micrographic surgery and IORT on an outpatient basis.

METHODS

Mohs surgery was used to clear the tumor in all fields except for the area of the spinal accessory nerve, which was preserved. IORT was then delivered to the area of nerve with possible residual tumor.

RESULTS

The patient remains clinically tumor free 42 months posttreatment. There were no complications.

CONCLUSION

Intraoperative radiation therapy can be effectively used in the outpatient setting as an adjunctive therapy after Mohs micrographic surgery.

Intraoperative radiation therapy for locally advanced recurrent rectal or rectosigmoid cancer

Recurrent rectal or rectosigmoid cancer is a difficult therapeutic problem. A treatment program of external beam irradiation, surgery, and intraoperative irradiation has been used for 41 patients. The 5-year actuarial local control and disease-free survival of all 41 patients was 30% and 16%, respectively. Subset analysis demonstrated differences in outcome by extent of surgical resection. The 5-year actuarial local control and disease-free survival of 27 patients undergoing complete resection was 47% and 21%, respectively. By contrast, the outcome of 14 patients undergoing partial resection was poor, with a 5-year actuarial local control and survival of 21% and 7%, respectively. Late complications included soft tissue or peripheral nerve injury, with many of these resolving within 4-18 months. Local control and disease-free survival rates are favorable in comparison with the results achieved by aggressive surgery. Patients who achieve a gross total resection at intraoperative irradiation have a markedly better prognosis than that of patients with residual gross disease.

Clinical toxicity of peripheral nerve to intraoperative radiotherapy in a canine model

PURPOSE

The clinical late effects of intraoperative radiotherapy (IORT) on peripheral nerve were investigated in a foxhound model.

METHODS AND MATERIALS

Between 1982 and 1987, 40 animals underwent laparotomy with intraoperative radiotherapy of doses from 0-75 Gy administered to the right lumbosacral plexus. Subsequently, all animals were monitored closely and sacrificed to assess clinical effects to peripheral nerve. This analysis reports final clinical results of all animals, with follow-up to 5 years.

RESULTS

All animals treated with > or = 25 Gy developed ipsilateral neuropathy. An inverse relationship was noted between intraoperative radiotherapy dose and time to neuropathy, with an effective dose for 50% paralysis (ED50) of 17.2 Gy. One of the animals treated with 15 Gy IORT developed paralysis, after a much longer latency than the other animals.

CONCLUSIONS

Doses of 15 Gy delivered intraoperatively may be accompanied by peripheral neuropathy with long-term follow-up. This threshold is less than that reported with shorter follow-up. The value of ED50 determined here is in keeping with data from other animal trials, and from clinical trials in humans.

Ultrastructural morphometric analysis of peripheral nerves after intraoperative irradiation

Intraoperative irradiation (IORT) is used to enhance local tumour control by using large, single doses while removing critical structures from the treatment field. Peripheral nerve remains a dose-limiting normal tissue that often cannot be removed from the field. To assess ultrastructural changes in canine sciatic nerve after IORT, computerized morphometric analysis of plastic sections and electron micrographs of nerve cross-sections was used. Surgically exposed sciatic nerves were irradiated with 6 MeV electrons to 12, 20 or 28 Gy. Twelve months after treatment dogs were killed humanely and the nerves from three dogs per dose group, including non-irradiated controls, were analyzed. Twelve months after 28-Gy IORT a significant decrease in nerve fiber density occurred. Nerve fiber loss was particularly prominent in the central portion of the nerve predominantly among large nerve fibers. Other nerve fiber parameters including fiber and axon area, diameter and perimeter, myelin thickness, form factor (measure of roundness), and G ratio (axon diameter/fiber diameter) did not show significant, dose-related changes. An increase in microtubule and neurofilament density in irradiated nerve axons was found. These changes are suggestive of radiation-induced hypoxia (damage to microvasculature) resulting in axon damage and subsequent nerve fiber loss as a possible mechanism of late radiation injury to peripheral nerve.

The use of intraoperative radiation therapy in radical salvage for recurrent cervical cancer: outcome and toxicity

OBJECTIVE

Our purpose was to evaluate the contribution of intraoperative radiation therapy in the management of recurrent cervical cancer.

STUDY DESIGN

Twenty-two patients were treated with electron beam intraoperative radiation therapy for recurrent cervical cancers that were confined to the pelvis but were too extensive to be adequately treated by radical surgery alone. All patients underwent extensive surgical dissection for exposure and maximal tumor resection. Doses of intraoperative radiation therapy ranged from 14 to 27.8 Gy (median 22 Gy). Twelve patients received intraoperative radiation therapy to address gross residual disease, and 10 patients were treated for microscopically positive or close surgical margins.

RESULTS

The five-year disease-specific survival and local control rates were 43% and 48%, respectively. There were trends toward better local control and disease-specific survival in patients with microscopic residual disease compared with those with gross residual disease. Seven patients had peripheral neuropathy related to treatment, and four of these cases resolved.

CONCLUSION

In carefully selected cases intraoperative radiation therapy contributes to radical salvage of patients with recurrent cervical cancer involving the pelvic wall.

Late radiation injury to muscle and peripheral nerves

Late radiation injury to muscles and peripheral nerves is infrequently observed. However, the success of radiation oncology has led to longer patient survival, providing a greater opportunity for late effects to develop, increase in severity and, possibly, impact the quality of life of the patient. In addition, when radiation therapy is combined with surgery and/or chemotherapy, the risk of late complications is likely to increase. It is clear that the incidence of complications involving muscles and nerves increases with time following radiation. The influence of volume has yet to be determined; however, an increased volume is likely to increase the risk of injury to muscles and nerves. Experimental and clinical studies have indicated that the alpha/beta ratio for muscle is approximately 4 Gy and, possibly, 2 Gy for peripheral nerve, indicating the great influence of fractionation on response of these tissues. This is of concern for intraoperative radiation therapy, and for high dose rate brachytherapy. This review of clinical and experimental data discusses the response of muscle and nerves late after radiation therapy. A grading system has been proposed and endpoints suggested.

Intraoperative irradiation after palliative surgery for locally recurrent rectal cancer

BACKGROUND

In patients with locally recurrent rectal cancer, long-term disease control and survival is uncommon with single-modality therapy. This report evaluates results achieved at the Mayo Clinic (Rochester, MN) with single- or combined-modality treatment, including intraoperative irradiation.

METHODS

From 1981 to 1988, 106 patients underwent palliative surgical resections at the Mayo Clinic for locally recurrent rectal cancer. None had evidence of extrapelvic disease, and 42 received intraoperative electron beam irradiation (IORT) as a component of treatment. Gross residual disease remained after maximal surgical resection in 34 of the 42 patients and 61 of the patients who did not receive IORT. The IORT dose was 15-20 Gy in 39 patients and 10, 25, and 30 Gy in the other 3. External beam irradiation (EBRT) was administered to 41 of the 42 patients (doses > or = 45 Gy to 38 patients).

RESULTS

Kaplan-Meier survival estimates at 3 and 5 years were analyzed for the 106 patients. Palliative surgical resection alone (12 patients) resulted in a 3-year survival of 8% and a 5-year survival of 0%. Statistically significant factors relative to survival based on the univariate analysis of all patients included amount of residual tumor (microscopic vs. gross, P = 0.032) treatment method (P = 0.005), IORT versus no IORT (P = 0.0006), type of symptoms (P = 0.0075), type of fixation (P < 0.0001), and preoperative Eastern Cooperative Oncology Group status (P = 0.03). For patients who received IORT, 3-year survival with gross residual tumor or presentation with pain was 44% and 43%, respectively. Factors not associated with survival (univariate) included extended versus conventional surgical resection, grade, age, and sex. The 3-year cumulative probability of distant metastasis was 60% in the patients who received IORT and 54% in those who did not. The 3-year local relapse rates were 40% versus 93% in patients who received IORT versus those who did not.

CONCLUSIONS

Although the addition of IORT to external irradiation and maximal surgical resection appears to improve local tumor control and survival in patients who undergo palliative surgical resection for locally recurrent rectal cancer, further gains in treatment are necessary. Considering the high rates of distant metastasis, more routine systemic therapy with 5-fluorouracil (5-FU) leucovorin, 5-FU levamisole, or all three needs to be incorporated into aggressive treatment approaches. In patients with gross residual tumor after maximum surgical resection, local tumor control is inadequate despite treatment combinations including IORT. The evaluation of radiation sensitizers or biologic modifiers during external irradiation and IORT is indicated.

Intra-operative radiotherapy in soft tissue sarcomas

We treated 31 soft tissue sarcoma bearing patients with intraoperative radiation therapy (IORT) with ages ranging from 26 to 71: first curative intent treatment, 16 patients; and recurrent tumors, 15 patients. The tumor site was the pelvis and the retroperitoneal spaces in 13 patients and the limbs or the trunk in 18 patients. The histological type was: malignant histiocytofibroma, 14 patients; liposarcomas, 10 patients; malignant schwanoma, 1 patient; leiomyosarcoma, 2 patients; hemangiopericytoma, 1 patient; embryonic rhabdomyosarcoma, 2 patients; and synovialosarcoma, 1 patient. All the patients were diagnosed without any distant metastatic evolution at the moment of the treatment. All the patients except one underwent a complete surgical excision without any gross residual disease and received an intraoperative radiation single dose of 10 Gy in one case, 12.5 Gy in one case, 13 Gy in one case, 15 Gy in 17 cases, 18 Gy in three cases, 20 Gy in seven cases and 25 Gy in one case. Thereafter the treatment was completed by a postoperative X-ray dose of 45-50 Gy in 4.5-5 weeks for 16 patients. Local control (LC) was obtained in 27 out of 31 patients (87%), with a minimal follow-up duration of 2 years. Eleven out of 31 patients died: seven with local control (one from an intercurrent disease, six from distant metastasis) and four with local failure inside the IORT fields. Twenty patients are alive with no evolutive disease in 19 cases and with a distant metastasis in one case.(ABSTRACT TRUNCATED AT 250 WORDS)