Pudendal nerve and internal pudendal artery damage may contribute to radiation-induced erectile dysfunction.

PURPOSE/OBJECTIVES: Erectile dysfunction is common after radiation therapy for prostate cancer; yet, the etiopathology of radiation-induced erectile dysfunction (RI-ED) remains poorly understood. A novel animal model was developed to study RI-ED, wherein stereotactic body radiation therapy (SBRT) was used to irradiate the prostate, neurovascular bundles (NVB), and penile bulb (PB) of dogs. The purpose was to describe vascular and neurogenic injuries after the irradiation of only the NVB or the PB, and after irradiation of all 3 sites (prostate, NVB, and PB) with varying doses of radiation. METHODS AND MATERIALS: Dogs were treated with 50, 40, or 30 Gy to the prostate, NVB, and PB, or 50 Gy to either the NVB or the PB, by 5-fraction SBRT. Electrophysiologic studies of the pudendal nerve and bulbospongiosus muscles and ultrasound studies of pelvic perfusion were performed before and after SBRT. The results of these bioassays were correlated with histopathologic changes. RESULTS: SBRT caused slowing of the systolic rise time, which corresponded to decreased arterial patency. Alterations in the response of the internal pudendal artery to vasoactive drugs were observed, wherein SBRT caused a paradoxical response to papaverine, slowing the systolic rise time after 40 and 50 Gy; these changes appeared to have some dose dependency. The neurofilament content of penile nerves was also decreased at high doses and was more profound when the PB was irradiated than when the NVB was irradiated. These findings are coincident with slowing of motor nerve conduction velocities in the pudendal nerve after SBRT. CONCLUSIONS: This is the first report in which prostatic irradiation was shown to cause morphologic arterial damage that was coincident with altered internal pudendal arterial tone, and in which decreased motor function in the pudendal nerve was attributed to axonal degeneration and loss. Further investigation of the role played by damage to these structures in RI-ED is warranted.

The growth of academic radiation oncology: a survey of endowed professorships in radiation oncology.

PURPOSE: The academic health of a medical specialty can be gauged by the level of university support through endowed professorships. METHODS AND MATERIALS: We conducted a survey of the 86 academic programs in radiation oncology to determine the current status of endowed chairs in this discipline. RESULTS: Over the past decade, the number of endowed chairs has more than doubled, and it has almost tripled over the past 13 years. The number of programs with at least one chair has increased from 31% to 65%. CONCLUSIONS: Coupled with other indicators of academic growth, such as the proportion of graduating residents seeking academic positions, there has been clear and sustained growth in academic radiation oncology.

American Society of Clinical Oncology 2008 clinical practice guideline update: use of chemotherapy and radiation therapy protectants.

PURPOSE: To update a clinical practice guideline on the use of chemotherapy and radiation therapy protectants for patients with cancer. METHODS: An update committee reviewed literature published since the last guideline update in 2002. RESULTS: Thirty-nine reports met the inclusion criteria: palifermin and dexrazoxane, three reports (two studies) each; amifostine, 33 reports (31 studies); and mesna, no published randomized trials identified since 2002. RECOMMENDATIONS: Dexrazoxane is not recommended for routine use in breast cancer (BC) in adjuvant setting, or metastatic setting with initial doxorubicin-based chemotherapy. Consider use with metastatic BC and other malignancies, for patients who have received more than 300 mg/m(2) doxorubicin who may benefit from continued doxorubicin-containing therapy. Cardiac monitoring should continue in patients receiving doxorubicin. Amifostine may be considered for prevention of cisplatin-associated nephrotoxicity, reduction of grade 3 to 4 neutropenia (alternative strategies are reasonable), and to decrease acute and late xerostomia with fractionated radiation therapy alone for head and neck cancer. It is not recommended for protection against thrombocytopenia, prevention of platinum-associated neurotoxicity or ototoxicity or paclitaxel-associated neuropathy, prevention of radiation therapy-associated mucositis in head and neck cancer, or prevention of esophagitis during concurrent chemoradiotherapy for non-small-cell lung cancer. Palifermin is recommended to decrease severe mucositis in autologous stem-cell transplantation (SCT) for hematologic malignancies with total-body irradiation (TBI) conditioning regimens, and considered for patients undergoing myeloablative allogeneic SCT with TBI-based conditioning regimens. Data are insufficient to recommend use in the non-SCT setting.

Influence of intravenous amifostine on xerostomia, tumor control, and survival after radiotherapy for head-and- neck cancer: 2-year follow-up of a prospective, randomized, phase III trial.

PURPOSE: To evaluate chronic xerostomia and tumor control 18 and 24 months after initial treatment with amifostine in a randomized controlled trial of patients with head-and-neck cancer; at 12 months after radiotherapy (RT), amifostine had been shown to reduce xerostomia without changing tumor control. METHODS AND MATERIALS: Adults with head-and-neck cancer who underwent once-daily RT for 5-7 weeks (total dose, 50-70 Gy) received either open-label amifostine (200 mg/m2 i.v.) 15-30 min before each fraction of radiation (n = 150) or RT alone (control; n = 153). RESULTS: Amifostine administration was associated with a reduced incidence of Grade > or =2 xerostomia over 2 years of follow-up (p = 0.002), an increase in the proportion of patients with meaningful (>0.1 g) unstimulated saliva production at 24 months (p = 0.011), and reduced mouth dryness scores on a patient benefit questionnaire at 24 months (p < 0.001). Locoregional control rate, progression-free survival, and overall survival were not significantly different between the amifostine group and the control group. CONCLUSIONS: Amifostine administration during head-and-neck RT reduces the severity and duration of xerostomia 2 years after treatment and does not seem to compromise locoregional control rates, progression-free survival, or overall survival.

A prospective, nonrandomized study of the impact of amifostine on subsequent hypothyroidism in irradiated patients with head and neck cancers.

The daily administration of subcutaneous amifostine to patients with head and neck cancers before each radiation fraction may reduce the long-term incidence of hypothyroidism (HT) after radiotherapy to the neck and may provide an additional indication for amifostine (Ethyol) use. Cancers of the head and neck afflict 40,000 patients yearly in the United States, and radiotherapy plays a pivotal role in the management of at least half of these patients. Patients commonly are treated with radiation alone, combined surgery and radiation, or definitive chemoradiotherapy. Local control of disease is achieved in many patients who are at risk for late sequelae of treatment that may diminish quality of life.

Gross tumor volume, critical prognostic factor in patients treated with three-dimensional conformal radiation therapy for non-small-cell lung carcinoma.

PURPOSE: Three-dimensional conformal radiation therapy (3D-CRT) has recently become widely available with applications for patients with non-small-cell lung cancer (NSCLC). These techniques represent a significant advance in the delivery of radiotherapy, including improved ability to delineate target contours, choose beam angles, and determine dose distributions more accurately than were previously available. The purpose of this study is to identify prognostic factors in a population of NSCLC patients treated with definitive 3D-CRT. METHODS AND MATERIALS: Between March 1991 and December 1998, 207 patients with inoperable NSCLC were treated with definitive 3D-CRT. Tumor targets were contoured in multiple sections from a treatment planning computed tomography (CT) scan. Three-dimensional treatment volumes and normal structures were reconstructed. Doses to the International Commission on Radiation Units and Measurements (ICRU) reference point ranged from 60 to 83.85 Gy with a median dose of 70 Gy. The median dose inhomogeneity was +/- 5% across planning target volume. Outcome was analyzed by prognostic factors for NSCLC including pretreatment patient and tumor-related factors (age, gender, race, histology, clinical stage, tumor [T] stage, and node [N] stage), parameters from our 3D-CRT system (gross tumor volume [GTV] in cm3), irradiation dose prescribed to isocenter, volume of normal lung exceeding 20 Gy (V20), and treatment with or without chemotherapy. The median follow-up time was 24 months (range, 7.5 months to 7.5 years). RESULTS: One and two-year overall survival rates for the entire group were 59% and 41%, respectively. Overall survival, cause-specific survival, and local tumor control were most highly correlated with the GTV in cm3. On multivariate analysis the independent variable most predictive of survival was the GTV. Traditional staging such as T, N, and overall clinical staging were not independent prognostic factors. Patients receiving ICRU reference doses > or =70 Gy had better local control and cause-specific survivals than those treated with lower doses (p = 0.05). Increased irradiation dose did not improve overall survival. CONCLUSIONS: GTV as determined by CT and 3D-CRT planning is highly prognostic for overall and cause-specific survival and local tumor control and may be important in stratification of patients in prospective therapy trials. T, N, and overall stage were not independent prognostic factors in this population of patients treated nonsurgically. The value of dose escalation beyond 70 Gy should be tested prospectively by clinical trial.