1/5. Potential reduction of the incidence of radiation-induced second cancers by using proton beams in the treatment of pediatric tumors.PURPOSE: To assess the potential influence of improved dose distribution with proton beams compared to conventional or intensity-modulated (IM) X-ray beams on the incidence of treatment-induced secondary cancers in pediatric oncology. methods AND MATERIALS: Two children, one with a parameningeal rhabdomyosarcoma (RMS) and a second with a medulloblastoma, were used as models for the purpose of this study. After defining the target and critical structures, treatment plans were calculated and optimized, four for the RMS case (conventional X-ray, IM x-rays, protons, and IM protons) and three for the irradiation of the spinal axis in medulloblastoma (conventional X-ray, IM x-rays, protons). Secondary cancer incidence was estimated using a model based on Publication No. 60 of the International Commission on Radiologic Protection. This model allowed estimation of absolute risks of secondary cancer for each treatment plan based on dose-volume distributions for the nontarget organs. RESULTS: Proton beams reduced the expected incidence of radiation-induced secondary cancers for the RMS patient by a factor of >or=2 and for the medulloblastoma case by a factor of 8 to 15 when compared with either IM or conventional X-ray plans. CONCLUSIONS: The potential for a significant reduction in secondary cancers with pediatric cancers after using proton beams (forward planned or IM) in the treatment of RMS and MBD in children and adolescents represents an additional argument supporting the development of proton therapy for most radiotherapy indications in pediatric oncology.- - - - - - - - - - ranking = 1keywords = radiation-induced (Clic here for more details about this article) |
2/5. Optic neuropathy secondary to radiotherapy for nasal melanoma.Optic neuropathy is a rare but important complication of radiotherapy used in the treatment of cancers of the head and neck, usually resulting in rapidly progressive blindness in one or both eyes. The case is presented of a 77-year-old woman with bilateral optic neuropathy resulting in blindness, secondary to radiotherapy for a melanoma of the nasal cavity. The onset of optic neuropathy occurred 9 months post-radiotherapy, at a cumulative dose of 6000 rad. The left eye was first involved, with the right eye becoming involved within 2 weeks. Despite treatment with oral anticoagulation and high dose intravenous methylprednisolone, there was progressive deterioration resulting in bilateral optic atrophy, with final visual acuities of perception of light in the right eye and no perception of light in the left eye. This case demonstrates that oral anticoagulation was ineffective in the treatment of progressive radiation-induced optic neuropathy.- - - - - - - - - - ranking = 0.2keywords = radiation-induced (Clic here for more details about this article) |
3/5. Postirradiation optic neuropathy in antral carcinoma.A case is described of a patient who developed radiation-induced optic neuropathy 18 months following cobalt-60 irradiation for carcinoma of the left maxillary antrum and ethmoid sinus. This case is unusual because of the early onset of the optic nerve damage following radiation therapy and the ultimate emergence of the eye involved by tumor compression as the better eye in terms of visual acuity.- - - - - - - - - - ranking = 0.2keywords = radiation-induced (Clic here for more details about this article) |
4/5. Postirradiation sarcoma of the head and neck: a report of three late sarcomas following therapeutic irradiation for primary malignancies of the paranasal sinus, nasal cavity, and larynx.Sarcoma of the head and neck region following irradiation for primary malignancy other than retinoblastoma has rarely been reported. Three cases of postirradiation sarcoma arising in the head and neck region following definitive radiotherapy for primary malignancies of the nasal cavity, paranasal sinuses, and larynx are presented. The intervals from initial radiation to diagnosis of sarcoma were 10 years, 10 1/2 years, and 12 1/2 years, respectively. The dosage ranged from 6000--6400 rads using conventional fractionation (1750--1811 ret) on a 60Cobalt teletherapy unit. methotrexate (25 mg I. V. every three days for seven doses) was utilized during the initial course of radiation in two of the three patients. The cases conform well to established criteria for the diagnosis of radiation-induced sarcoma. Postirradiation sarcoma of the head and neck region is a remote hazard that must be weighed against the benefits of curative radiation therapy, particularly when treating in the presence of bone disease or when treating retinoblastoma or benign lesions.- - - - - - - - - - ranking = 0.2keywords = radiation-induced (Clic here for more details about this article) |
5/5. Visual loss following treatment of sphenoid sinus carcinoma.A 71-year-old woman developed complete third nerve palsy and total blindness of the right eye one month after completing a course of radiotherapy for sphenoid sinus carcinoma over a 13-month period. Differential diagnosis included recurrence of the tumor, radiation-induced second neoplasm, empty sella with chiasmal prolapse and secondary chiasmal arachnoid adhesions, and radionecrosis. magnetic resonance imaging demonstrated gadolinium contrast enhancement of the right intracranial optic nerve and chiasm, suggesting a radionecrosis process.- - - - - - - - - - ranking = 0.2keywords = radiation-induced (Clic here for more details about this article) |