Iodine-125 brachytherapy in the treatment of colorectal adenocarcinoma metastatic to the liver

BACKGROUND

The liver is the site of distant failure in > 33% of patients with colorectal adenocarcinoma. Liver resection is the only potentially curative option in these patients. Patients with incompletely resected liver lesions (due to the proximity to critical vascular structures) are at high risk of dying of progressive disease in the liver. This pilot study was performed to determine whether the intraoperative implantation of iodine-125 (I-125) seeds could reduce the recurrence and improve the survival of patients with incompletely resected liver metastases.

METHODS

Fifty-six patients with unresectable or residual disease after surgical resection of liver metastases from colorectal carcinoma underwent permanent implantation with I-125 seeds to deliver 160 gray to the periphery of the target volume.

RESULTS

The 1-, 3-, and 5-year actuarial control rates of liver disease were 41%, 23%, and 23%, respectively. The 5-year actuarial control of liver disease was better for patients with a solitary metastasis (39%) than for those with multiple metastases (9%) (P = 0.04). The 1-, 3-, and 5-year actuarial overall survival rates were 71%, 25%, and 8%, respectively (median, 20 months; 95% confidence interval, 17-23). The radiation-related complications were minimal.

CONCLUSIONS

I-125 liver brachytherapy is feasible with minimal radiation-related morbidity. Good prognostic factors for long term liver control and survival are the presence of a solitary metastasis, postresection minimal residual disease requiring smaller volume implants, and no prior liver resections. Future prospective trials should be directed toward this patient population, which has the highest probability of obtaining improved results from the local dose escalation provided by brachytherapy. Adjuvant regional chemotherapy clearly is needed due to the high rate of liver recurrence and ultimate death from liver failure observed in spite of liver resection and brachytherapy.

Iodine-125 brachytherapy in the treatment of colorectal adenocarcinoma metastatic to the liver

BACKGROUND

The liver is the site of distant failure in > 33% of patients with colorectal adenocarcinoma. Liver resection is the only potentially curative option in these patients. Patients with incompletely resected liver lesions (due to the proximity to critical vascular structures) are at high risk of dying of progressive disease in the liver. This pilot study was performed to determine whether the intraoperative implantation of iodine-125 (I-125) seeds could reduce the recurrence and improve the survival of patients with incompletely resected liver metastases.

METHODS

Fifty-six patients with unresectable or residual disease after surgical resection of liver metastases from colorectal carcinoma underwent permanent implantation with I-125 seeds to deliver 160 gray to the periphery of the target volume.

RESULTS

The 1-, 3-, and 5-year actuarial control rates of liver disease were 41%, 23%, and 23%, respectively. The 5-year actuarial control of liver disease was better for patients with a solitary metastasis (39%) than for those with multiple metastases (9%) (P = 0.04). The 1-, 3-, and 5-year actuarial overall survival rates were 71%, 25%, and 8%, respectively (median, 20 months; 95% confidence interval, 17-23). The radiation-related complications were minimal.

CONCLUSIONS

I-125 liver brachytherapy is feasible with minimal radiation-related morbidity. Good prognostic factors for long term liver control and survival are the presence of a solitary metastasis, postresection minimal residual disease requiring smaller volume implants, and no prior liver resections. Future prospective trials should be directed toward this patient population, which has the highest probability of obtaining improved results from the local dose escalation provided by brachytherapy. Adjuvant regional chemotherapy clearly is needed due to the high rate of liver recurrence and ultimate death from liver failure observed in spite of liver resection and brachytherapy.

The American brachytherapy society survey of brachytherapy practice for carcinoma of the cervix in the United States

PURPOSE

The purpose of this study was to survey the brachytherapy practice for cervical cancer in the United States.

METHODS

The Clinical Research Committee of the American Brachytherapy Society (ABS) performed a retrospective survey of individual physicians of the ABS and American Society of Therapeutic Radiologists and Oncologists regarding the details of the brachytherapy techniques they personally used in the treatment of cervical cancer patients for the year 1995. The replies (some of which may have been an estimate only) were tabulated. The scope of this survey did not allow us to verify the data by chart audits.

RESULTS

A total of about 3500 questionnaires were mailed out; 521 responses were received. Of these responders, 206 (40%) did not perform any brachytherapy for carcinoma of the cervix in 1995. Of the other 315 responders reporting a total of 4892 patients treated in 1995, 88% used low dose rate (LDR) while 24% used high dose rate (HDR). There was a wide variation in the doses used. For LDR treatments, the median total external beam radiation therapy (EBRT) dose was 45 and 50 Gy and the LDR dose was 42 and 45 Gy for early and advanced cancers, respectively. For HDR treatments, the median EBRT dose was 48 and 50 Gy and the median HDR dose was 29 and 30 Gy for early and advanced cancers, respectively. The median dose per fraction was 6 Gy for a median of five fractions. Interstitial brachytherapy was used as a component of the treatment in 6% of the patients by 21% of responders. Very few responders treated with pulsed or medium dose rates.

CONCLUSION

This retrospective survey showed the current brachytherapy practice pattern in the treatment of cervical cancer in the United States and can serve as a basis for future prospective national brachytherapy data registry. There was wide variation in the practice pattern, emphasizing the urgent need for consensus on these issues.

Brachytherapy for the interventional cardiologist and vascular surgeon

PURPOSE

There has been recent interest in the use of brachytherapy for the possible prevention of restenosis after angioplasty. However, this field is unfamiliar to most interventional cardiologists. This article is meant to serve as an introduction to the principles of brachytherapy especially as it applies to intravascular brachytherapy. Because the intended audience is the interventional cardiologist, the details of physics, radiobiology, and radiation jargon has been kept at a minimum.

METHODS

The main advantages of brachytherapy are that it can irradiate small volumes and conform to the target volume while sparing the surrounding normal tissues from the deleterious effects of irradiation. Various gamma- or beta-emitting radioisotopes can deliver the brachytherapy dose. In general, the beta emitters have fewer radiation exposure hazards, but the limited penetration of beta emitters can be a problem if deeper tissues need to be irradiated. Gamma sources can irradiate deeper but suffer from greater radiation exposure hazards. It should be remembered that the biological effects of radiation depend on a number of parameters, including the radiation modality, dose, dose rate, fractionation, treatment duration, dose prescription point, and the volume irradiated. The use of low energy isotopes, beta emitters, and remote-controlled afterloading has reduced the radiation exposure to the medical caregivers.

CONCLUSION

Intravascular brachytherapy is currently considered to be experimental. Those wishing to start a new intravascular brachytherapy program should comply with the required federal and state regulatory guidelines issued by the Nuclear Regulatory Commission, Food and Drug Administration, and their individual Institutional Review Board.

Medicare physician referral patterns

OBJECTIVE

To study patterns of referral between primary and specialty care providers among Medicare beneficiaries and to identify correlates of the probability of referral.

DATA SOURCES

The 1992 and 1993 Medicare Current Beneficiary Survey (MCBS), including associated claims data. MCBS data are linked to the Area Resource File (ARF) and the Physician Identification Master Record (PIMR).

STUDY DESIGN

This is a retrospective design using cross-sectional descriptive and multivariate correlational analysis. Estimates are made for two years. Key variables include two alternative definitions of referrals, patient socio-demographic and health status, physician characteristics, and county-level descriptors.

DATA COLLECTION

The MCBS is a panel survey of a stratified random sample of Medicare beneficiaries begun in 1991. The data are linked to Medicare claims records for survey respondents. The ARF is a health resources data set that contains more than 7,000 variables at the county level, including information on health facilities, health professions, services resources and utilization, and socioeconomic and environmental characteristics. The PIMR is a record of all physicians in the United States and describes their professional characteristics.

PRINCIPAL FINDINGS

The overall rate of physician referrals in the MCBS, approximately 10 percent, is higher than that found in prior research, as is the level of self-referral to specialists at about 70 percent. Depending on the dependent variable definition, between 60 and 85 percent of all Medicare beneficiaries had at least one referral, and the average number of referrals per person per year was greater than two. Referrals show a multi-directional pattern rather than a simple pattern of primary to specialty care, with referrals between primary care physicians, referrals between specialists, and referrals from specialty to primary care being not uncommon. Strong predictors of referral include patient health and patient insurance coverage and income. Physician factors do not contribute much to explaining referrals.

CONCLUSIONS

Medicare referral patterns are similar to those found in other studies. Patient factors appear to be a more important factor in explaining referrals than was estimated from prior research. Additional research is needed to explain the more complex dynamics of referral patterns.

Spontaneous remission of primary central nervous system lymphoma: report of 3 cases and discussion of pathophysiology

Primary central nervous system lymphoma (PCNSL) is a relatively uncommon disease in which spontaneous remission is exceedingly rare. We are reporting three cases of primary CNS lymphoma with spontaneous regression in two to eight weeks, from the time of the initial diagnosis. The remission lasted for four years in the first case, two years in the second, and one year in the third case. Tissue diagnosis was made in the first two cases after relapse, and in the third case a biopsy was done at the initial presentation. The literature and the possible pathophysiological mechanisms of this interesting phenomenon are discussed.

Radioimmunoguided-intraoperative radiation therapy in colorectal carcinoma: a new technique to precisely define the clinical target volume

PURPOSE

The clinical target volume (CTV) to be irradiated by intraoperative radiation therapy (IORT) after resection is generally based on the surgeon's estimation of close margins. We have developed a new technique, radioimmunoguided-intraoperative radiation therapy (RIG-IORT), that uses an intraoperative hand-held gamma-detecting probe to define areas of residual microscopic disease containing radiolabeled monoclonal antibodies to tumor associated antigen, to more precisely delineate the CTV for IORT.

METHODS AND MATERIALS

Patients were injected i.v. with 2 mCi 125I- radiolabeled CC49 antibody approximately 3 weeks before surgery. They then underwent radioimmunoguided surgery (RIGS) with maximal resection of tumor. A hand-held gamma-detecting probe (Neoprobe 1000) was used intraoperatively to detect and resect areas of high radioactivity, representing tumor. Areas with persistently high probe counts after resection were the areas of occult residual disease, and represented the CTV to be irradiated. The IORT was given with either 6-9 MeV electron beam from a dedicated linear accelerator, or with high-dose-rate brachytherapy from a remote afterloader. If all RIGS-positive tissue had been resected, or if widely disseminated disease remained, the patient was not considered for IORT.

RESULT

This technique was used in 31 patients with colorectal adenocarcinoma recurrent into the pelvis (n = 23) or paraortic nodes (n = 8). The CTV for IORT was delineated by increased RIGS count in 13 of 19 patients (68%) with microscopic residual, and in 11 of 12 patients (92%) with gross residual. In the other 7 patients, the tumor area did not accumulate the radiolabeled antibody; therefore, these tumor beds were irradiated based on the surgeon's estimation of close margins. Hence, overall, the RIG-IORT technique was used to define the tumor bed for IORT in 24 of 31 patients (77%). This technical report focuses on the development of the RIG-IORT technique and does not address the outcome results of the treated patients.

CONCLUSION

A new technique, RIG-IORT, which uses radiolabeled monoclonal antibodies to precisely determine the CTV for IORT, is described. Whether the use of this technique will lead to improved tumor control will only be known upon the outcome analysis of RIG-IORT-treated patients compared with those obtained using traditional IORT techniques.

Intraoperative high dose rate brachytherapy can be used to salvage patients with previously irradiated head and neck recurrences

PURPOSE

To develop a novel technique, intraoperative high-dose rate brachytherapy (IOHDR), in the treatment of previously irradiated head and neck cancers located at anatomical sites inaccessible to intraoperative electron beam radiotherapy (IOERT).

METHODS

Between October 1992 and June 1997, seven patients (median age = 65 yrs; range = 52 to 71 years) with previously irradiated head and neck recurrences at anatomical sites inaccessible to IOERT in the base of skull were treated with IOHDR after maximal resection for microscopic residual disease. Treatment volume ranged from 6 cc to 24 cc. Six patients received 15 Gy of IOHDR at 0.5 cm; one received 10 Gy using custom-made surface foam applicators.

RESULTS

The median follow-up was 59 months (range 33 to 67 months). It was technically feasible to deliver IOHDR in all seven patients at sites that were inaccessible to IOERT. The morbidity (observed in two patients) was acceptable and generally surgically related. Four of seven patients (57%) were locally controlled at IOHDR site. Two failed regionally, outside the IOHDR treated sites. The disease-free survival ranged from 3 to 30 months (median 9 months) with two patients still alive, disease-free at 28 and 30 months.

CONCLUSIONS

IOHDR can be used, with limited toxicity, to treat previously irradiated head and neck cancers at sites inaccessible to IOERT. We are currently evaluating the addition of limited EBRT dose to improve the local control of these poor prognosis recurrent tumors.

Iodine-125 brachytherapy in the treatment of colorectal adenocarcinoma metastatic to the liver

BACKGROUND

The liver is the site of distant failure in > 33% of patients with colorectal adenocarcinoma. Liver resection is the only potentially curative option in these patients. Patients with incompletely resected liver lesions (due to the proximity to critical vascular structures) are at high risk of dying of progressive disease in the liver. This pilot study was performed to determine whether the intraoperative implantation of iodine-125 (I-125) seeds could reduce the recurrence and improve the survival of patients with incompletely resected liver metastases.

METHODS

Fifty-six patients with unresectable or residual disease after surgical resection of liver metastases from colorectal carcinoma underwent permanent implantation with I-125 seeds to deliver 160 gray to the periphery of the target volume.

RESULTS

The 1-, 3-, and 5-year actuarial control rates of liver disease were 41%, 23%, and 23%, respectively. The 5-year actuarial control of liver disease was better for patients with a solitary metastasis (39%) than for those with multiple metastases (9%) (P = 0.04). The 1-, 3-, and 5-year actuarial overall survival rates were 71%, 25%, and 8%, respectively (median, 20 months; 95% confidence interval, 17-23). The radiation-related complications were minimal.

CONCLUSIONS

I-125 liver brachytherapy is feasible with minimal radiation-related morbidity. Good prognostic factors for long term liver control and survival are the presence of a solitary metastasis, postresection minimal residual disease requiring smaller volume implants, and no prior liver resections. Future prospective trials should be directed toward this patient population, which has the highest probability of obtaining improved results from the local dose escalation provided by brachytherapy. Adjuvant regional chemotherapy clearly is needed due to the high rate of liver recurrence and ultimate death from liver failure observed in spite of liver resection and brachytherapy.

Use of brachytherapy to preserve function in children with soft-tissue sarcomas

Pediatric soft-tissue sarcomas are managed with a multimodality treatment program that includes surgery, chemotherapy, and external-beam radiotherapy (teletherapy). The use of teletherapy in young children can result in significant long-term toxicities (especially growth retardation of bones and organs). Brachytherapy, if feasible, is an attractive alternative for the treatment of pediatric soft-tissue sarcomas, since it irradiates small volumes and, thus, may potentially minimize complications. Aggressive chemotherapy is used to achieve systemic control and tumor shrinkage, thereby facilitating conservative surgery and brachytherapy. The brachytherapy techniques used in children are similar to those employed in adults. Low-dose-rate (LDR) brachytherapy with manually afterloaded removable iridium-192 is commonly used, although it is associated with some radiation exposure hazards. Low-energy radionuclides (e.g., iodine-125) and remote afterloading technology have been used to reduce radiation exposure hazards. Brachytherapy, in conjunction with chemotherapy and surgery but without supplementary teletherapy, has produced good local control with acceptable late complications in selected patients with localized tumors. Brachytherapy can also be used as a boost to moderate dose external-beam radiotherapy for more extensive tumors. The use of newer modalities, such as high-dose-rate, pulsed-dose-rate, and intraoperative brachytherapy, has allowed brachytherapy to be given to younger children and infants, but the long-term morbidities of these modalities need to be established.

Remediation of attention deficits in head injury

Head injury is associated with psychological sequelae which impair the patient's psychosocial functioning. Information processing, attention and memory deficits are seen in head injuries of all severity. We attempted to improve deficits of focused, sustained and divided attention. The principle of overlapping sources of attention resource pools was utilised in devising the remediation programme. Tasks used simple inexpensive materials. Four head injured young adult males with post concussion syndrome underwent the retraining program for one month. The patients had deficits of focused, sustained and divided attention parallel processing, serial processing, visual scanning, verbal learning and memory and working memory. After the retraining programme the deficits of attention improved in the four patients. Serial processing improved in two patients. Parallel processing and neuropsychological deficits did not improve in any patient. The symptom intensity reduced markedly and behavioural functioning improved in three of the four patients. The results supported an association between improving attention and reduction of symptom intensity. Attention remediation shows promise as a cost effective, time efficient and simple technique to improve the psychological and psychosocial functioning of the head injured patient.

Bamboo, rats and famines: famine relief and perceptions of British paternalism in the Mizo hills (India)

As the British entered the Mizo hills (part of the Indo-Burmese range of hills, then known as the Lushai hills) to chase the headhunting tribal raiders and try to gain control over them by securing a foothold in the heart of the hills at Aizawl, they witnessed an amazing ecological phenomenon: a severe famine apparently caused by rats. The Mizo hills are covered extensively by various species of bamboo, which periodically rot, flower and seed. The bamboo seeds appeared to be a delicious food item for jungle rats, which emerged in massive numbers to devour them, and the consumption of bamboo seeds seemed to produce a vast increase in the rodent population. Once the millions of rats had exhausted the bamboo seed, they began to attack the standing crops in the fields. As they devoured the grains the resulting scarcity of food led to massive hardship, starvation and deaths....

Use of combined intraoperative radiotherapy and 125I brachytherapy in incompletely resected recurrent colorectal carcinoma

This technique paper describes a new treatment strategy which involves the combination of 125I brachytherapy and intraoperative radiotherapy (IOERT) in the treatment of recurrent colorectal adenocarcinoma. IOERT is used to encompass the areas of presumed microscopic disease with the IOERT dose being kept below the threshold for severe neuropathy. Brachytherapy with 125I is used to boost areas of gross disease within the IOERT treated area that would otherwise require potentially neurotoxic IOERT doses to achieve local control. The outcome results of patients treated with this technique will be reported at a later date after further patient actual and longer follow-up.

The American Brachytherapy Society perspective on intravascular brachytherapy

BACKGROUND

Recent clinical studies indicate that intravascular brachytherapy (IVB) can reduce the rate of restenosis substantially after angioplasty procedures. However, no clinical guidelines exist for optimal therapy.

METHODS

The members of the IVB Subcommittee of the American Brachytherapy Society (ABS) identified the areas of consensus and controversies in IVB to issue the ABS perspective on IVB, based on analysis of published reports and the clinical experience of the members in brachytherapy.

RESULTS

IVB is still experimental. The long-term efficacy, toxicity, the target tissue, and dose required for IVB are not established. The ABS recommends that IVB procedures must be performed, with careful attention to radiation-related issues, in the context of controlled multidisciplinary clinical trials with the approval of the institutional review board, the Nuclear Regulatory Commission, the Food and Drug Administration, and under an Investigational Device Exemption. The therapeutic radiologist, with a qualified radiation physicist, is responsible for dose prescription and delivery and needs to be present during the IVB procedure as part of this multidisciplinary team. The long-term outcome from these studies should be reviewed critically and published in peer-reviewed journals. The ABS endorsed the dosimetric guidelines of the American Association of Physicists in Medicine Task Group 60 (AAPM TG-60) report. The ABS recommends that dose specification be defined clearly; to allow comparisons between studies, the dose should be prescribed at 2 mm from the source for intracoronary brachytherapy and at an average luminal radius of +2 mm for peripheral vascular brachytherapy. The prescription doses at the above point is generally in the 12-18 Gy range. Comprehensive procedures for quality assurance, radiation protection, and emergencies should be in place before initiating an IVB program. Higher energy beta sources, lower energy gamma sources, dose-volume histograms, and correlation of three-dimensional reconstructions of delivered dose with patterns of failure are areas for further research.

CONCLUSION

The ABS perspective on IVB is presented to assist the interventional team in developing protocols for the use of IVB in the prevention of restenosis. Long-term outcome data with a standardized reporting system are needed to establish the role of brachytherapy in preventing vascular restenosis. Endovascular brachytherapy is a new and evolving modality, and these recommendations are subject to modifications as new data become available.

Intraoperative electron beam radiotherapy for previously irradiated advanced head and neck malignancies

PURPOSE

This is a retrospective review to evaluate the role of surgery and intraoperative electron beam radiotherapy (IOERT) in the treatment of patients with previously irradiated advanced head and neck cancers.

METHODS AND MATERIALS

Between January 1992 and March 1997, 38 patients (31 males, 7 females; median age of 62 years) with recurrent head and neck cancer were treated with maximal resection and IOERT at the Ohio State University (OSU). All had been previously treated with full-course radiotherapy (median 65.1 Gy, range 50-74.4 Gy). Twenty-nine patients (76%) had previously undergone one or more surgical procedures. After maximal surgery the tumor bed was treated with IOERT (single field in 36 patients and 2 fields in 2 patients), most commonly with 6 MeV electrons (87%). The dose administered (at 90% isodose line) was 15 Gy for close or microscopically positive margins in 34 patients and 20 Gy for gross disease in 1 patient. Further external beam radiation therapy (EBRT) was not given.

RESULTS

After a median follow-up of 30 months (range 8-39 months), 24 of the 38 patients (66%) recurred within the IOERT field. Median time to IOERT failure was 6 months (95% CI: 4.3-7.7). The 6-month, 1-, and 2-year control rates within the IOERT volume were 41%, 19%, and 13%, respectively. Thirty of the 38 patients (79%) recurred in locoregional areas. Median time to locoregional failure was 4 months (95% CI: 3.3-4.7). The 6-month, 1-, and 2-year locoregional control rates were 33%, 11%, and 4%, respectively. Distant metastases occurred in 7 patients, 5 in association with IOERT failure and 2 with locoregional failure. Median overall survival was 7 months (95% CI: 4.7-9.3). The 6-month, 1-, 2-, and 3-year actuarial survival rates were 51%, 21%, 21%, and 8%, respectively. Major treatment-related complications occurred in 6 patients (16%).

CONCLUSION

IOERT alone, at the dose used, is not sufficient for control of recurrent, previously irradiated head and neck cancers. Since higher IOERT doses are associated with high morbidity, we are currently evaluating the addition of limited EBRT dose and/or brachytherapy to improve the local control of these poor prognostic recurrent tumors, with acceptable morbidity.

Vascular endothelial growth factor in Alzheimer's disease and experimental cerebral ischemia

Several growth factors have been implicated in the pathogenesis of Alzheimer's disease (AD). We considered whether the vascular endothelial growth factor (VEGF) is involved in the vascular pathology associated with most cases of AD. We observed enhanced VEGF immunoreactivity in clusters of reactive astrocytes in the neocortex of subjects with AD compared to elderly controls. VEGF reactivity was also noted in walls of many large intraparenchymal vessels and diffuse perivascular deposits. In addition, we established that astrocytic and perivascular VEGF reactivity was enhanced in cerebral cortex of rats subjected to cerebral ischemia and to chronic hypoxia; experimental conditions known to be associated with astrogliosis and angiogenesis. We suggest the increased VEGF reactivity, also observed in infarcted human brain tissue, implicates compensatory mechanisms to counter insufficient vascularity or reduced perfusion (oligemia) apparent in AD.

125Iodine brachytherapy for colorectal adenocarcinoma recurrent in the pelvis and paraortics

PURPOSE

To evaluate the results of 125I brachytherapy in colorectal cancers recurrent in the pelvis and paraortics.

METHODS AND MATERIALS

From September 1989 to January 1997, 29 patients with colorectal adenocarcinoma recurrent in the pelvis or the paraortic nodes were treated intraoperatively with permanent 125iodine seed implantation at the James Cancer Center of The Ohio State University (OSU). All patients had undergone prior surgery; 72% had prior EBRT. The implanted residual tumor volume was microscopic in 38% and gross in 62%. The implanted area (median 25 cc) received a median minimal peripheral dose of 140 Gy to total decay. An omental pedicle was used to minimize irradiation of the bowel. Five patients received additional postimplant EBRT (20-50 Gy; median 30 Gy).

RESULTS

The 1-, 2-, and 4-year actuarial local-regional control rates were 38%, 17%, and 17%, respectively, with a median time to local failure of 11 months (95% CI 10-12 months). The first manifestation of disease progression in 52 % of the patients was local-regional. In addition, 22 patients (75%) developed distant metastases. The 1-, 2-, and 4-year actuarial overall survival rates were 70%, 35%, and 21%, (median = 18 months; 95% CI: 14-22 months). Overall survival was better for patients smaller volume implants (p = 0.007), with a lower total activity implanted (p = 0.0003), with a smaller number of implanted sites (p = 0.004), and with microscopic residual disease (p = 0.01). Patients receiving additional EBRT also had a better prognosis (p = 0.005). Local tumor progression was the cause of death in 34% of the patients who have died at the time of this report and 56% died of distant metastases. Of the patients, 13 (45%) experienced 15 toxic events, including 3 patients (10%) with enteric fistula. Neuropathy was not observed.

CONCLUSIONS

125I brachytherapy can be successfully used for salvage in patients with recurrent colorectal cancer. Patients with isolated, microscopic, or minimal gross residual disease requiring small-volume implants and those receiving additional EBRT have a better prognosis. Postimplant EBRT is now routinely added, even for previously irradiated patients, in an attempt to improve local control. Compared to IOERT and IOHDR, 125I brachytherapy is not associated with clinical neuropathy, probably due to the continuous low dose rate irradiation delivered by the 125I seeds.

Simplified non-looping functional loop technique for HDR brachytherapy

The loop technique has been employed in interstitial implantation of head and neck cancers for decades. However, cable-driven afterloading sources may be unable to negotiate the curve of the loop. The technique allows separate afterloading of each catheter ensuring a good dose distribution to the surface of the implanted structure.

Cholinergic lesions of the rat brain by ibotenic acid and 192 IgG-saporin: effects on somatostatin, substance P and neuropeptide Y levels in the cerebral cortex and the hippocampus

Impairment of the basal forebrain cholinergic system is an important change in the brains of Alzheimer's disease patients. Various neurotoxins have been used to achieve this in animal models. In this study the effects of chemical lesions by ibotenic acid (IBO), a glutamate analogue and by 192 IgG-saporin, a highly specific immunotoxin against cholinergic neurons, were investigated. The toxins were delivered stereotaxically into the brains of young Sprague-Dawley rats which were later sacrificed by decapitation. Choline acetyltransferase (ChAT) activity was measured by radioenzymatic assay and substance P (SP), neuropeptide Y (NPY) and somatostatin (SOM) levels by radioimmunoassay. Decreased ChAT and SOM levels were observed in the cortex and the hippocampus in both experiments. Cortical SP levels were increased after IBO lesions but were unaffected after 192 IgG-saporin lesions. NPY levels remained unchanged in both experiments. The results indicate that there were specific changes in neuropeptide contents in the cortex and hippocampus in response to cholinergic damage in the rat brain.

Feasibility of intraoperative high-dose rate brachytherapy to boost low dose external beam radiation therapy to treat pediatric soft tissue sarcomas

PURPOSE

To determine if a single intraoperative high-dose-rate brachytherapy (IOHDR) dose can be used in conjunction with low dose external beam radiation therapy (EBRT) to treat soft tissue malignancies in children with reduced morbidity.

METHODS

From March 1992 to February 1995, six pediatric patients (4 boys, 2 girls; ages ranging from 4-13 years; median 10.5 years) were treated with IOHDR in conjunction with EBRT, chemotherapy, and radical surgery at nine sites not treatable by standard intraoperative electron beam radiation therapy techniques. The IOHDR dose was 10 Gy (at 7 sites with microscopic residual disease) or 12.5 Gy (at 2 sites with minimal gross residual disease) prescribed at 0.5 cm depth. The treatment volume varied from 9-96 cc (mean 30.3 cc). IOHDR was used in these patients because the tumor locations prevented positioning and insertion of conventional intraoperative electron beam applicators. The EBRT dose was limited to 27-30.6 Gy (median dose 27.4 Gy) postoperatively in all patients to minimize growth retardation or altered organ function. The median initial EBRT field size was 211 cm2 (range 25-483), with a median of two fields per patient (range 1-2).

RESULTS

After a median follow-up of 40 months (range 22-62 months), all the patients were alive, five of them without evidence of disease. The other patient, with stage IV undifferentiated synovial sarcoma developed regrowth of pulmonary metastases at 14 months and local failure at 34 months. Toxicity was seen in two patients. One patient developed recurrent urinary infections and ureteral stenosis after 6 months and required a left nephrectomy. Another developed mild to moderate loss of visual acuity and impaired orbital growth after 6 months.

CONCLUSIONS

Use of IOHDR in conjunction with low dose EBRT to obtain local control and long-term disease-free survival in pediatric soft tissue sarcomas is feasible with acceptable toxicity. Tumor beds not treatable with standard electron beam intraoperative radiation therapy could be satisfactorily encompassed with IOHDR.

Interstitial brachytherapy in the management of primary carcinoma of the cervix and vagina

PURPOSE

The purpose of this study was to determine the role of interstitial brachytherapy in the management of selected primary cancers of the cervix and the vagina.

METHODS

Thirty-nine previously untreated patients with histologically confirmed carcinoma of the cervix (31 patients) and of the vagina (8 patients) were treated by a combination of external beam radiotherapy and fluoroscopic-guided interstitial brachytherapy between November 1989 and May 1995 at the Ohio State University Medical Center because they were not suitable for standard intracavitary brachytherapy. Clinical indications for interstitial brachytherapy were extensive parametrial involvement in 22 patients, extensive vaginal involvement in 10, and poor vaginal anatomy in 7.

RESULTS

With a median follow-up of 36 months (range 12-66 months), 16 patients (51%) with cervical carcinomas and 5 patients (62.5%) with vaginal carcinomas have experienced local control of their tumor. The local control was better for tumors < 4 cm in largest diameter compared to tumors > 6 cm in largest diameter. The 5-year actuarial survival was 34 and 38% for cervical and vaginal cancers, respectively. Only 1 patient experienced grade 3 complications (2.5%).

CONCLUSIONS

Interstitial brachytherapy can be safely used to treat patients unsuitable for standard intracavitary brachytherapy. When intracavitary dose distribution is expected to be suboptimal, interstitial brachytherapy is a good alternative.