Biomedical subjects

W M Mendenhall

Publications and source records attributed to W M Mendenhall.

At least 91 records · Page 5Linked to original sources

PubMed1996

The risk of hemorrhage after radiosurgery for arteriovenous malformations.

Two hundred and one patients with arteriovenous malformations (AVMs) treated radiosurgically between May 1988 and February 1995 are analyzed in this study. Twelve patients sustained a posttreatment hemorrhage during this period. Pretreatment factors associated with increased hemorrhage risk were identified in 11 of these patients and included arterial aneurysms, venous aneurysms, venous outflow obstruction, periventricular location, prior embolization, and prior surgical treatment. A detailed statistical analysis, using both Poisson regression and parametric survival regression techniques, was undertaken to determine whether radiosurgery had any effect on the risk of hemorrhage, when compared to the natural history of the disease, in those patients in whom a complete angiographic cure was not achieved. No evidence was found to support a statistically significant departure from the natural hemorrhage rate at any time period after radiosurgical treatment. Significant risk factors for hemorrhage appeared to correlate with increasing AVM volume.

Adolescent↗

PubMed1996

Preliminary results of linear accelerator radiosurgery for acoustic schwannomas.

In this paper the authors evaluate the results of linear accelerator (LINAC)-based stereotactic radiosurgery for acoustic schwannomas. Fifty-six patients underwent LINAC-based stereotactic radiosurgery for acoustic schwannomas at the University of Florida between July 1988 and November 1994. Each patient was followed for a minimum of 1 year or until death; no patient was lost to follow up. One or more follow-up magnetic resonance images or computerized tomography scans were obtained in 52 of the 56 patients. Doses ranged between 10 and 22.5 Gy with 69.6% of patients receiving 12.5 to 15 Gy. Thirty-eight patients (68%) were treated with one isocenter and the dose was specified to the 80% isodose line in 71% of patients. Fifty-five patients (98%) achieved local control after treatment. The 5-year actuarial local control rate was 95%. At the time of analysis, 48 patients were alive and free of disease, seven had died of intercurrent disease, and one was alive with disease. Complications developed in 13 patients (23%). The likelihood of complications was related to the dose and treatment volume: 10 to 12.5 Gy to all volumes, three (13%) of 23 patients; 15 to 17.5 Gy to 5.5 cm3 or less, two (9%) of 23 patients; 15 to 17.5 Gy to more than 5.5 cm3, five (71%) of seven patients; and 20 to 22.5 Gy to all volumes, three (100%) of three patients. Linear accelerator-based stereotactic radiosurgery results in a high rate of local control at 5 years. The risk of complications is related to the dose and treatment volume.

Aged↗

PubMed1996

Does neck stage predict local control after irradiation for head and neck cancer?

The impact of neck stage (N stage) on local control after treatment for head and neck cancer is controversial. This article reviews the pertinent literature. Based on this review, the authors conclude that although N stage may be inversely related to local control, the relationship is relatively weak. Hence, current data are insufficient to justify altering treatment of the primary lesion based solely on N stage.

Head and Neck Neoplasms↗

PubMed1996

Response of the normal eye to high dose radiotherapy.

Radiation therapy of tumors near the eye or optic nerves often requires incidental irradiation of these structures, even when they are not clinically involved by tumor. Depending on the radiation treatment volume and dose required, radiation injury to the lens, lacrimal apparatus, retina, or optic nerve may result. The time to expression and severity of injury are dose-dependent. This paper reviews the results of 157 patients who were followed for a minimum of 3 years after radiotherapy for primary extracranial tumors at the University of Florida, in which the lacrimal gland, lens, retina, and/or optic nerve(s) received irradiation. This review shows that, after treatment at approximately 1.8 to 2.0 Gy per fraction, the incidence of severe dry-eye syndrome, retinopathy, and optic neuropathy appears to increase steeply after doses of 40, 50, and 60 Gy, respectively.

Dose-Response Relationship, Radiation↗

PubMed1996

Squamous cell carcinoma of the anal margin treated with radiotherapy.

Squamous cell carcinoma of the anal margin is relatively rare. We present a series of patients treated with radiotherapy alone or combined with concomitant chemotherapy at our institution and review the pertinent literature. Ten patients with AJCC T2N0 and T3N0 squamous cell carcinoma of the anal margin were treated with radiotherapy alone or radiotherapy plus chemotherapy at the University of Florida between 1979 and 1993. All patients had a follow-up for at least 2 years, and no patient was lost to follow-up. All ten patients have remained continuously disease free after treatment. Three patients died of intercurrent disease at 29, 37 and 113 months after treatment. The remaining seven patients were alive and disease-free from 24 to 143 months after radiotherapy. No patient experienced a major complication and all retained a functional anal sphincter. Based on our experience and a review of the literature, superficial, well to moderately differentiated, T1 and T2 cancers may be successfully treated with radiotherapy alone or a local excision. More advanced lesions are best treated with combined radiotherapy and concomitant chemotherapy. Abdominoperineal resection should be reserved for those presenting with faecal incontinence and those with locally recurrent disease after previous radiotherapy.

Abdomen↗

PubMed1996

Squamous cell carcinoma of the anal margin.

Based on our experience and a review of the literature, we conclude that superficial, well- to moderately differentiated T1 cancers of the anal margin may be successfully treated with radiotherapy alone or local excision. Stage T2 lesions have a significant risk of inguinal lymph node metastases and should be treated with radiotherapy to the primary tumor in conjunction with elective inguinal lymph node irradiation. The best treatment for T3 and T4 lesions is radiotherapy to the primary lesion and regional nodes (inguinal and pelvic) combined with concomitant chemotherapy. Abdominoperineal resection (APR) should be reserved for patients who have fecal incontinence at presentation or locally recurrent disease after previous radiotherapy.

Adult↗

PubMed1995

Treatment selection factors for stereotactic radiosurgery of intracranial metastases.

PURPOSE: To define treatment selection criteria for patients with intracranial metastases treated with stereotactic radiosurgery. METHODS AND MATERIALS: Between August 1989 and July 1993, 25 patients with intracranial metastases (28 lesions) were treated with stereotactic radiosurgery at the University of Florida. Thirteen patients were treated for progressive intracranial disease after external-beam radiotherapy, and 12 were treated with radiosurgery as an adjunct to initial treatment. Minimum eligibility criteria included histologic verification of primary disease, Karnofsky performance status 50% or greater, three or fewer intracranial metastases, radiographically distinct lesion(s) 4 cm or less in diameter, and reasonably well-controlled primary disease. Univariate and multivariate analyses tested the prognostic significance of Karnofsky performance status, lesion volume, number of lesions, treatment dose (both external beam and stereotactic), histology, site of primary disease, and time interval (less than or greater than 1 year) from primary diagnosis to development of intracranial metastasis or from treatment of intracranial disease to recurrence. RESULTS: Local control was achieved in 84% of 28 lesions treated. The only significant prognostic indicator among the tested variables was the interval to development or recurrence of intracranial metastasis. CONCLUSION: Although stereotactic radiosurgery improves local control rates and is likely to offer improved palliation for a select cohort of patients, the selection criteria for such patients remain poorly defined. Our data suggest that an interval of greater than 1 year from primary disease diagnosis to development of intracranial metastasis, or from treatment of intracranial metastasis to its recurrence, defines a patient cohort that is more likely to benefit from this treatment technique.

Adenocarcinoma↗

PubMed1995

Salvage surgery following radiation failure in squamous cell carcinoma of the supraglottic larynx.

PURPOSE: We analyzed the clinical course of patients who developed local (primary) recurrence following high-dose irradiation of squamous cell carcinoma of the supraglottic larynx. METHODS AND MATERIALS: Between October 1964 and July 1991, 206 patients with previously untreated squamous cell carcinoma of the supraglottic larynx underwent radiotherapy with curative intent. Local failure occurred in 46 (22%) patients. Successful surgical salvage was defined as no evidence of recurrent cancer for at least 2 years after salvage surgery and continuously thereafter. RESULTS: Sixteen patients did not undergo salvage surgery because of refusal (7 patients), severe medical illness (2 patients), concurrent distant metastasis (5 patients), or unresectable neck disease (2 patients). Twenty-six patients underwent total laryngectomy, and 4 patients had a voice-sparing procedure. Successful salvage was achieved in 50% of patients who underwent surgery. The rate of successful salvage did not correlate with preirradiation T-stage or time to failure after irradiation. Most of the failures after surgery were because of failure to control the primary cancer. The overall rate of postsurgical complications was 37%. No operative or perioperative deaths occurred. The 5-year survival rate for all 46 patients, calculated from the date of irradiation failure, was 20%, while the 5-year survival rate after salvage surgery for the 30 patients who underwent the procedure was 29%. CONCLUSION: There are few data in the literature regarding the clinical outcome in patients whose tumors are not controlled by initial radiotherapy. In the current and previous series, one-half to two-thirds of patients who developed primary failure underwent salvage surgery, which was successful in approximately half of the operated patients, leading to a 25-30% rate of long-term disease-free survival among the entire group of patients who developed failure.

Adult↗

PubMed1995

Linac radiosurgery for high-grade gliomas: the University of Florida experience.

PURPOSE: Stereotactic radiosurgery has been reported as a promising boost technique for the treatment of selected patients with high-grade glioma. The first 11 patients given this treatment at the University of Florida are reported. METHODS AND MATERIALS: Six patients with glioblastoma multiforme and five with anaplastic astrocytoma were carefully selected for treatment with linac radiosurgery. All patients had a Karnofsky performance status > or = 90%. Median age of patients was 42.1 years. External-beam radiotherapy delivered a median dose of 60 Gy. Stereotactic radiosurgery was delivered to the enhancing tumor volume without margin. Median treatment volume was 14 cm3 (equivalent sphere diameter, 3 cm). The maximum volume of any tumor treated was 22.5 cm3 (equivalent sphere diameter, 3.5 cm). Median stereotactic radiosurgery boost dose was 12.5 Gy, and median prescription sphere was the 80% isodose shell. RESULTS: Despite rigorous selection and aggressive stereotactic boost irradiation, this patient cohort had a median actuarial survival of 17 months. All patients have had progression of intracranial disease within 1 year of radiosurgery, and only 3 of 11 remain alive with a median follow-up of 13 months. CONCLUSION: These results differ significantly from others reported. Comparative analysis suggests tumor volume may be an important prognostic factor in patients treated with stereotactic radiosurgery. Future studies need to define appropriate patient cohorts for the boost technique.

Adolescent↗

PubMed1995

Radiotherapy in the management of temporal bone chemodectoma.

Forty patients with 42 temporal bone chemodectomas were treated with radiotherapy alone (37 tumors) or subtotal resection and irradiation (5 tumors) at the University of Florida between 1968 and 1992. Thirty-three lesions were previously untreated, whereas 9 had undergone prior treatment (surgery, 6 lesions; radiotherapy, 1 lesion; or both, 2 lesions) and were treated for locally recurrent disease. All 3 patients who received prior radiotherapy had been treated at other institutions. Patients had minimum follow-up times as follows: 2 years, 40 patients (100%); 5 years, 31 patients (78%); 10 years, 21 patients (53%); 15 years, 16 patients (40%); 20 years, 9 patients (23%); and 25 years, 2 patients (5%). The local control rate at 20 years, calculated by the Kaplan-Meier product-limit method for the overall group of 42 lesions, was 89%. The likelihood of cause-specific survival at 20 years was 94%. The incidence of treatment-related complications was acceptable. We conclude that irradiation offers a high probability of tumor control with relatively minimal risks for patients with chemodectomas of the temporal bone.

Journal Article↗

PubMed1995

Downstaging of esophageal cancer after preoperative radiation and chemotherapy.

OBJECTIVE: This retrospective, nonrandomized review evaluates 125 patients with esophageal carcinoma (adenocarcinoma and squamous cell) who underwent either surgery only or preoperative chemotherapy and/or radiation therapy followed by surgery. Major end points were survival and postchemoradiation downstaging. METHODS: Forty-four patients underwent radiation therapy of 4500 cGy over 5 weeks. Fluorouracil and cisplatin were administered on the first and fifth week of radiotherapy. Ninety-eight patients underwent "potentially curative" resections-transhiatal esophagectomy (70), Lewis esophagogastrectomy (25), and left esophagogastrectomy (3). All patients with preoperative adjuvant therapy underwent endoscopy and biopsy before surgery. RESULTS: There were no differences in overall mortality (5%) or surgical complications in either group. Fourteen of 44 patients (32%) downstaged to complete pathologic response, with 5-year survival of 57%. Fifteen of 44 patients (34%) downstaged to microscopic residual tumor, with 1- and 3-year survival of 77% and 31%, respectively. Twenty-eight of 29 patients in the two downstaged groups were lymph node negative. Overall, 5-year survival in the adjuvant therapy plus surgery group versus surgery only was 36% and 11% (p = 0.04). Five-year survival in lymph node-negative adjuvant therapy and surgery patients was 49% (p = 0.005). Positive nodes in the surgery only group was 48% versus 23% in the adjuvant therapy and surgery group (p = 0.02). CONCLUSION: Although retrospective and nonrandomized, these results suggest that preoperative chemoradiation results in significant clinical and pathologic downstaging, increases survival, and may sterilize local and regional lymph nodes, accounting for both downstaging and survival statistics.

Adenocarcinoma↗

PubMed1995

Nasal mucociliary clearance after radiation therapy.

Irradiation has been demonstrated to cause decreased mucociliary clearance in animal models. We sought to verify this effect clinically by using the saccharin transport test to evaluate nasal mucociliary clearance in 9 patients previously treated with radiation therapy to the nasal cavity. The patients also completed a questionnaire examining the prevalence of nasal symptoms before and after radiation therapy. Patients who received radiation therapy had no clearance of saccharin from the nasal cavity at a minimum of 20 minutes. The controls had a median clearance time of 5 minutes. The patients noted a higher prevalence of nasal congestion, drainage, and facial pain after radiation therapy. This study demonstrates that radiation therapy to the nasal cavity causes a decrease in nasal mucociliary clearance. This alteration should be considered when selecting therapy for malignancies in the nasal area.

Administration, Intranasal↗

PubMed1995

Linear accelerator radiosurgery for arteriovenous malformations: the relationship of size to outcome.

Between May, 1988 and August, 1993, 158 patients with arteriovenous malformations (AVMs) were treated radiosurgically at the University of Florida. A mean dose of 1560 cGy was directed to the periphery of the lesions, which had a mean volume of 9 cc (0.5 to 45.3 cc). One hundred thirty-nine of these individuals were treated with one isocenter. The mean follow-up interval was 33 months with clinical information available on 153 of these patients. Patients were followed until magnetic resonance (MR) studies suggested complete AVM thrombosis. An arteriogram was then performed, if possible, to verify occlusion status. If arteriography revealed any persistent nidus at 36 months posttreatment, the residual nidus was re-treated. Outcome categories of AVMs analyzed included the following possibilities: 1) angiographic cure; 2) angiographic failure; 3) re-treatment; 4) MR image suggested cure; 5) MR image suggested failure; 6) patient refused follow-up evaluation; 7) patient lost to follow-up study; or 8) patient deceased. The endpoints for success or failure of radiosurgery were as follows: angiographic occlusion (success), re-treatment (failure), and death due to AVM hemorrhage (failure). Fifty-six patients in this series reached one of the endpoints. Successful endpoints were seen in 91% of AVMs between 1 and 4 cc in volume, 100% of AVMs 4 to 10 cc in volume, and 79% of AVMs greater than 10 cc in volume. The more traditional measure of radiosurgical success, percentage of angiograms showing complete obliteration, was obtained in 81% of AVMs between 1 and 4 cc in volume, 89% of AVMs between 4 and 10 cc in volume, and 69% of AVMs greater than 10 cc in volume. A detailed analysis of the relationship of all outcome categories to size is presented.

Adolescent↗

PubMed1995

Radiation therapy for sinus malignancies.

Primary tumors arising in the nasal cavity and paranasal sinuses usually are considered together. Except in the nasal cavity, where occasional lesions present early because of nasal obstruction, most lesions are advanced at presentation, and the exact site of origin may be uncertain. Radiation therapy may be used alone or in combination with surgery in the management of patients with squamous cell carcinoma of these sites.

Aged↗

PubMed1994

Radiation optic neuropathy after megavoltage external-beam irradiation: analysis of time-dose factors.

PURPOSE: To investigate the risk of radiation-induced optic neuropathy according to total radiotherapy dose and fraction size, based on both retrospective and prospectively collected data. METHODS AND MATERIALS: Between October 1964 and May 1989, 215 optic nerves in 131 patients received fractionated external-beam irradiation during the treatment of primary extracranial head and neck tumors. All patients had a minimum of 3 years of ophthalmologic follow-up (range, 3 to 21 years). The clinical end point was visual acuity of 20/100 or worse as a result of optic nerve injury. RESULTS: Anterior ischemic optic neuropathy developed in five nerves (at mean and median times of 32 and 30 months, respectively, and a range of 2-4 years). Retrobulbar optic neuropathy developed in 12 nerves (at mean and median times of 47 and 28 months, respectively, and a range of 1-14 years). No injuries were observed in 106 optic nerves that received a total dose of < 59 Gy. Among nerves that received doses of > or = 60 Gy, the dose per fraction was more important than the total dose in producing optic neuropathy. The 15-year actuarial risk of optic neuropathy after doses of > or = 60 Gy was 11% when treatment was administered in fraction sizes of < 1.9 Gy, compared with 47% when given in fraction sizes of > or = 1.9 Gy. The data also suggest an increased risk of optic nerve injury with increasing age. CONCLUSION: As there is no effective treatment of radiation-induced optic neuropathy, efforts should be directed at its prevention by minimizing the total dose, paying attention to the dose per fraction to the nerve, and using reduced-field techniques where appropriate to limit the volume of tissues that receive high-dose irradiation.

Adolescent↗

PubMed1994

Radiation retinopathy after external-beam irradiation: analysis of time-dose factors.

PURPOSE: To investigate the risk of radiation-induced retinopathy according to total radiation dose and fraction size, based on both retrospective and prospectively collected data. METHODS AND MATERIALS: Between October 1964 and May 1989, 68 retinae in 64 patients received fractionated external-beam irradiation during the treatment of primary extracranial head and neck tumors. All patients had a minimum of 3 years of ophthalmologic follow-up (range, 3 to 26 years; mean, 9 years; median, 8 years). RESULTS: Twenty-seven eyes in 26 patients developed radiation retinopathy resulting in visual acuity of 20/200 or worse. The mean and median times to the onset of symptoms attributable to retinal ischemia were 2.8 and 2.5 years, respectively. Fourteen of the injured eyes developed rubeosis iridis and/or neovascular glaucoma. Radiation retinopathy was not observed at doses below 45 Gy, but increased steadily in incidence at doses > or = 45 Gy. In the range of doses between 45 and 55 Gy, there was an increased risk of injury among patients who received doses per fraction of > or = 1.9 Gy (p = .09). There was also a trend toward increased risk of injury among patients who received chemotherapy (two of two vs. four of ten in the 45-51 Gy range; p = .23). The lowest dose associated with retinopathy was 45 Gy delivered to a diabetic patient by twice-a-day fractionation. The data did not suggest an increased risk of radiation retinopathy with increasing age. CONCLUSION: The current study suggests the importance of total dose as well as dose per fraction, and adds support to a small body of literature suggesting that patients with diabetes mellitus or who receive chemotherapy are at increased risk of injury. A sigmoid dose-response curve is constructed from our current data and data from the literature.

Adolescent↗

PubMed1994

Severe dry-eye syndrome following external beam irradiation.

PURPOSE: There are limited data in the literature on the probability of dry-eye complications according to radiotherapy dose. This study investigates the risk of radiation-induced severe dry-eye syndrome in patients in whom an entire orbit was exposed to fractionated external beam irradiation. METHODS AND MATERIALS: Between October 1964 and May 1989, 33 patients with extracranial head and neck tumors received irradiation of an entire orbit. Most patients were treated with 60Co. The dose to the lacrimal apparatus was calculated at a depth of 1 cm from the anterior skin surface, the approximate depth of the major lacrimal gland. The end point of the study was severe dry-eye syndrome sufficient to produce visual loss secondary to corneal opacification, ulceration, or vascularization. RESULTS: Twenty patients developed severe dry-eye syndrome. All 17 patients who received doses > or = 57 Gy developed severe dry-eye syndrome. Three (19%) of 16 patients who received doses < or = 45 Gy developed severe dry-eye syndrome; injuries in the latter group were much slower to develop (4 to 11 years) than in the higher dose group, in whom corneal vascularization and opacification were usually pronounced within 9-10 months. There were no data for the range of doses between 45.01 and 56.99 Gy. The data did not suggest an increased risk of severe dry-eye syndrome with increasing age. CONCLUSION: Data from the current series and the literature are combined to construct a sigmoid dose response curve. The incidence of injury increases from 0% reported after doses < or = 30 Gy to 100% after doses > or = 57 Gy.

Adolescent↗

PubMed1994

Radiotherapy alone for carcinoma of the vagina: the importance of overall treatment time.

PURPOSE: Review treatment results, complications, and the importance of overall treatment time for carcinoma of the vagina treated with radiotherapy alone. METHODS AND MATERIALS: Between October 1964 and October 1990, 65 patients with histologically confirmed carcinoma of the vagina received definitive radiotherapy at the University of Florida. All patients had a minimum 2-year follow-up. Most patients were treated with a combination of external-beam radiotherapy and brachytherapy. The probability of pelvic control, cause-specific survival, and complications was calculated and multivariate analyses were performed. The log-rank test was used to determine significance levels between the curves. RESULTS: The 5-year cause-specific survival rates were, Stage 0 (six patients), 100%; Stage I (17 patients), 94%; Stage IIA (six patients), 80%; Stage IIB (ten patients), 39%; Stage III (twn patients), 79%; and Stage IVA (six patients), 62%. The pelvic control rates at 5 years were: Stage 0, 100%; Stage I, 87%; Stage IIA, 88%; Stage IIB, 68%; Stage III, 80%; and Stage IVA, 67%. The parameters of stage, patient age, total dose to primary site, and overall treatment time were evaluated in a multivariate analysis. The single most important predictor of pelvic control was overall treatment time. If the entire course of radiotherapy (external beam + implant) was completed within 9 weeks (63 days), the pelvic control rate was 97%. The pelvic control rate was only 54% if treatment time extended beyond 9 weeks (p = .0003). The rate of severe complications was 12%, and the incidence increased with increasing total primary dose. CONCLUSION: Radiotherapy alone can cure a significant proportion of patients with carcinoma of the vagina. Treatment should be completed without significant interruption, preferably within 9 weeks.

Brachytherapy↗