Low-dose External Beam Radiotherapy Research Articles

Radiation Therapy for Subretinal Neovascularizadon

Purpose: To evaluate low-dose external beam irradiation and plaque radiotherapy for the treatment of subretinal neovascularization.Methods: The authors treated 137 patients with radiation therapy for subretinal neovascularization. Herein, they examine a subset of 75 patients with exudative age-related macular degeneration who were treated with (4- or 6-MV photons) external beam irradiation at a dose of 1200 to 1500 cGy to the affected macula. In addition, six patients were treated with palladium 103 ophthalmic plaque brachytherapy to an equivalent retinal apex dose of 1200 to 1500 cGy. The authors compared the intralesional, intraocular, and intracranial radiation dose distributions of each treatment modality. Early Treatment Diabetic Retinopathy Study-type visual acuity determinations, ophthalmic examinations, and angiography were performed before and after treatment. Clinical evaluations were performed in a nonrandomized and unmasked fashion.Results: Episcleral plaque brachytherapy was found to provide a higher average radiation dose within the neovascular tissues while delivering less radiation to most normal ocular (both eyes) and all intracranial structures. Both forms of radiotherapy were associated with decreased hemorrhages, exudates, and leakage of neovascular membranes. Ten (13%) patients receiving external beam radiotherapy had transient epiphora and ocular irritation.Conclusion: Observation and laser photocoagulation of subfoveal neovascularization have been associated with poor visual outcomes. Pilot experience suggests that low-dose radiotherapy offers a method to treat subretinal neovascularization without destroying the overlying retina. Although the authors' radiation distribution studies favored plaque radiotherapy, additional factors such as relative efficacy, expense, convenience, and safety must be investigated.

Extramedullary Hematopoiesis Manifesting as a Symptomatic Pleural Effusion

The occurrence of extramedullary hematopoiesis in the pleura is rare and is usually asymptomatic. It is generally diagnosed on postmortem examination. Herein we describe a 61-year-old woman with agnogenic myeloid metaplasia who sought medical assessment because of progressive dyspnea. Thoracentesis yielded sanguineous fluid with 10% myeloblasts. A 99mTc bone marrow scan demonstrated increased tracer activity throughout both lungs, an outcome consistent with extramedullary hematopoiesis. Fine-needle aspiration and video-assisted thoracoscopy were considered but deferred because of the potential risk of profuse bleeding. Treatment with low-dose external beam irradiation to the left posterior pleura was successful. To date, no hemothorax has recurred.

Percutaneous iodine-125 seed implantation for carcinoma of the prostate.

This study was performed to assess the early results of treating stages T1-T3 adenocarcinoma prostate with either Iodine-125 (125I) implant alone (Group 1), for smaller more well differentiated cancers, or with low dose external beam radiation followed by a 125I boost (XRT + 125I) (Group 2) for larger less well differentiated tumours. Eighty-six patients were followed for between 11 and 60 months with a mean follow up of 26.1. All patients were followed by regular prostate specific antigen (PSA) evaluations, and digital rectal examinations (DRE). Eighty patients had a follow-up biopsy at 1 year. Prostate specific antigen progression-free survival (PSA-PFS) was determined and defined. Complications and potency were also assessed. Early results of 125I prostate seed implantation are very promising especially for selected cases of localized carcinoma.

Original Articles: Prostate Cancer: Detailed Preliminary Analysis of Iodine-125 Implantation for Localized Prostate Cancer Using Percutaneous Approach

Recent developments have permitted accurate seed placement and dosimetry for interstitial brachytherapy of selected patients with localized prostate cancer. We present our experience with 76 patients divided into 2 groups. Group 1 included 45 patients with smaller, more well differentiated tumors, usually less than 2 cm. in diameter on digital rectal examination or transrectal ultrasound and a Gleason score of less than 7 who were treated with 125iodine alone. Group 2 consisted of 31 patients with localized tumors greater than 2 cm. in diameter and/or a Gleason sum equal to or greater than 7 who were treated with low dose external beam radiation followed by 125iodine boost 4 weeks later. Complete clinical progression-free survival, including prostate specific antigen, digital rectal examination and biopsy, was 51% for group 1 and 63.3% for group 2, with a mean followup of 26.3 months. Prostate specific antigen progression-free survival was 97.7% for group 1 and 94.7% for group 2. These results appear to be superior to external beam radiation only although longer followup is needed to substantiate these favorable early results. The procedures were well tolerated with good potency sparing. They were performed on an outpatient or short stay basis and provided a good alternative to external beam radiation only or hormonal treatment for select patients with localized prostate cancer who may not be candidates for radical prostatectomy.

Original Articles

Recent developments have permitted accurate seed placement and dosimetry for interstitial brachytherapy of selected patients with localized prostate cancer. We present our experience with 76 patients divided into 2 groups. Group 1 included 45 patients with smaller, more well differentiated tumors, usually less than 2 cm. in diameter on digital rectal examination or transrectal ultrasound and a Gleason score of less than 7 who were treated with 125iodine alone. Group 2 consisted of 31 patients with localized tumors greater than 2 cm. in diameter and/or a Gleason sum equal to or greater than 7 who were treated with low dose external beam radiation followed by 125iodine boost 4 weeks later. Complete clinical progression-free survival, including prostate specific antigen, digital rectal examination and biopsy, was 51% for group 1 and 63.3% for group 2, with a mean followup of 26.3 months. Prostate specific antigen progression-free survival was 97.7% for group 1 and 94.7% for group 2. These results appear to be superior to external beam radiation only although longer followup is needed to substantiate these favorable early results. The procedures were well tolerated with good potency sparing. They were performed on an outpatient or short stay basis and provided a good alternative to external beam radiation only or hormonal treatment for select patients with localized prostate cancer who may not be candidates for radical prostatectomy.

PAPILLARY THYROID CANCER IN CHILDREN

Papillary thyroid cancer has been reported in large numbers of children from regions close to the Chernobil nuclear explosion. The papillary thyroid cancer in these children has been reported to be more aggressive than are similar tumors arising in other settings. To examine the effect of previous radiation therapy on aggressiveness of childhood papillary thyroid cancer, we examined the records of 90 children (66 girls and 24 boys) less than 17 years of age receiving primary surgical treatment for papillary thyroid cancer at the Mayo Clinic between 1940 and 1990. 21 patients (23%) had received previous radiation therapy-usually comprising low-dose external beam radiation for benign conditions such as thymic enlargement. Median followup was 30 years.Conclusion: Children with previous radiation therapy had larger tumors and more frequent neck node metastases than did children without previous radiation. Grade of tumor, extrathyroidal invasion, tumor recurrence and mortality were not significantly different in radiated and nonradiated patients.

Preliminary results of a prospective randomized trial of intraoperative (IORT) and low dose external beam radiotherapy [formula omitted] high dose external beam radiotherapy as adjunctive therapy in resectable soft tissue sarcomas of the retroperitoneum

Preliminary results of a prospective randomized trial of intraoperative (IORT) and low dose external beam radiotherapy [formula omitted] high dose external beam radiotherapy as adjunctive therapy in resectable soft tissue sarcomas of the retroperitoneum