ABSTRACT
Prophylactic cranial irradiation (PCI) is performed on patients with limited or extensive small-cell lung cancer to reduce incidence of brain metastases and prolong survival. PCI may induce neurocognitive impairment. Decreasing irradiation of neural stem cells (NSC) might reduce PCI-induced toxicity. We tested the feasibility of reducing irradiation doses to neural stem cell (NSC) regions while maintaining prescribed doses to the planned target volume (PTV). Irradiation plans utilizing intensity-modulated radiotherapy (IMRT), helical TomoTherapy, and RapidArc for 10 consecutive lung cancer patients were evaluated. The dose distribution, dose-volume histograms, and dose homogeneity indexes were analyzed. Planned and actual dose distributions were compared by dosimetric analysis. Both helical tomotherapy and LINAC-based IMRT reduced the radiation dose to the NSC regions by approximately 45% while maintaining the full dose to the rest of brain. Measured dose distributions matched the planned dose distributions.Protecting the regions of active neurogenesis is technically feasible. Whether reducing the dose by 35% to 45% is sufficient to reduce treatment toxicity, however, can only be addressed in a randomized study. Further reducing the dose within the NSC region might also significantly decrease the dosage to the PTV.
Subject(s)
Adenocarcinoma/radiotherapy , Cranial Irradiation , Lung Neoplasms/radiotherapy , Neurogenesis/radiation effects , Organ Preservation , Radiotherapy, Intensity-Modulated , Small Cell Lung Carcinoma/radiotherapy , Cells, Cultured , Feasibility Studies , Follow-Up Studies , Humans , Neural Stem Cells/radiation effects , Prognosis , Radiometry , Radiotherapy Planning, Computer-Assisted , Tomography, Spiral ComputedABSTRACT
AIMS: Most papers dealing with radiosurgery for cerebral arteriovenous malformations (AVMs) present the results of gamma-knife treatment, whereas linac radiosurgery is becoming increasingly popular. Moreover, there is still much uncertainty about the rationale of combined endovascular and radiosurgical treatment. The aims of this study were to evaluate obliteration and rebleeding rates, and to determine factors influencing obliteration and adverse effects after linac-based stereotactic radiosurgery for cerebral AVMs. MATERIALS AND METHODS: Records of 62 consecutive patients were analysed. Thirty-one had partial embolisation, five surgery, 29 had no prior treatment. The mean follow-up was 28.4 months. The mean volume treated was 11.7cm(3) and included embolised portions of AVMs. Actuarial obliteration rates and annual bleeding hazard rates after radiosurgery were calculated using Kaplan-Meier survival and life table analyses. RESULTS: Actuarial obliteration rates after 1, 2 and 3 years of follow-up were 17, 36 and 40%, respectively. Prior embolisation did not influence the obliteration rate. In 77.3% of patients, obliteration occurred during the first 2 years of follow-up. Annual bleeding hazard rates after stereotactic radiosurgery were 3.4 and 1.1% during the first and second year of follow-up, respectively. Non-symptomatic imaging abnormalities were detected in 33.9% of patients after a median time of 8.8 months. The Spetzler-Martin grade, AVM score, radiation dose, volume and AVM nidus < 3cm significantly influenced the probability of obliteration. A dose less than 15Gy significantly reduced the probability of obliteration. CONCLUSION: At least a 3 year follow-up is required to accurately assess the outcome. The best effects of the treatment are achieved for small (<3cm), low-grade lesions with a low AVM score. The bleeding risk after stereotactic radiosurgery gradually decreases.
Subject(s)
Arteriovenous Fistula , Intracranial Arteriovenous Malformations/pathology , Intracranial Arteriovenous Malformations/surgery , Radiosurgery , Adolescent , Adult , Aged , Child , Female , Follow-Up Studies , Humans , Male , Middle Aged , Survival Rate , Treatment Outcome , Young AdultABSTRACT
The aim of this study was the assessment of diagnostic value of thyroglobulin serum measurement in patients with DTC during endogenous TSH stimulation. Thyroglobulin was measured by immunofluorometric method (Delfia-Wallac) in patients after combined surgery and I131 ablation. Predictive values for two threshold levels 10 and 30 ng/ml were compared. At 5 years follow up it has been demonstrated, that Tg values higher than 10 ng/ml were the true signals of DTC relapse only in 46% patients. Tg values higher than 30 ng/ml were associated with disease progression in 65% of patients. Thus, we accept Tg concentration of 30 ng/ml measured during endogenous TSH stimulation as a good cut-off limit for the detection of DTC progression. Reduction of this threshold up to 10 ng/ml is associated with the increased risk of false positive results.
