Individual patient information to select patients for different radiation techniques.

BACKGROUND AND PURPOSE: Proton therapy is an emerging technique in radiotherapy which results in less dose to the normal tissues with similar target dose than photon therapy, the current standard. Patient-level simulation models support better decision making on which patients would benefit most. MATERIALS AND METHODS: A simulation model was developed tracking individual patients' status regarding the primary tumour and multiple complications. As a proof of principle, the model was populated based on information from a cohort of 1013 head and neck cancer patients. Dose-volume parameters for photon and proton radiation treatment plans were then fed into the model to compare outcomes in terms of length and quality of life and select patients that would benefit most. RESULTS: The illustrative model could adequately replicate the outcomes of photon therapy in the cohort. Improvements from proton therapy varied considerably between patients. The model projects medium-term outcomes for specific individuals and determines the benefits of applying proton rather than photon therapy. CONCLUSIONS: While the model needs to be fed with more and especially recent data before being fully ready for use in clinical practice, it could already distinguish between patients with high and low potential benefits from proton therapy. Benefits are highest for patients with both good prognosis and high expected damage to adjacent organs. The model allows for selecting such patients a priori based on patient relevant outcomes.

Reduced growth hormone secretion after cranial irradiation contributes to neurocognitive dysfunction.

The objective of this study was to investigate the relation between growth hormone (GH) and attentional electro-cortical responses to task-relevant stimuli (N2b), target detections, speed of responding, P300 latencies, and performance on neuropsychological tests in 19 patients who received external beam radiation therapy for brain tumors in adulthood. In addition, we studied the association between IGF-I and activation of the motor cortex responses (lateralized readiness potential, LRP). Brain function was assessed using event-related potentials (ERPs) during a go/no go selective-attention task, including N2b, P300 and selective motor preparation as reflected in the LRP. Correlations were calculated between peak GH levels after a standardized growth hormone-releasing hormone (GHRH)-arginine test, plasma IGF-I, and cognitive functions. We separately studied four patients who were diagnosed with GHD according to the GHRH-arginine test. Performance on WAIS digit span backward and the Rey-Osterrieth complex figure test correlated positively with GH peak. GHD patients performed worse than non-GHD patients on Stroop interference, trail making B/A attentional shifting and Rey-Osterrieth complex figure test. At trend-level significance, trails A performance was better in patients with lower GH levels and higher radiation doses, and GHD participants detected fewer targets in the go/no go selective attention task. N2b was not significantly altered by GH status. Furthermore, plasma IGF-I was positively correlated with the sum of digit span forward and backward. No relations with P300 were observed. In this study only 21% (4/19) of the patients who received fractionated radiotherapy for a non-endocrine brain tumor were diagnosed with GHD. GHD in these patients was associated with impaired interference control, attentional shifting, and visual long-term memory. The results for interference control and attentional shifting suggest an additional effect of the radiation history.

Cognitive performance in older males is associated with growth hormone secretion.

Decreases in GH secretion with age may contribute to cognitive changes associated with aging. We evaluated the relation between GH secretion and cognition in elderly males by assessing correlations between GH secretion and performance on cognitive tests in conjunction with recording of event-related potentials (ERPs) to assess underlying neurophysiological mechanisms. GH secretion of 17 elderly male participants was assessed by a GHRH-GHRP-6 test. Standardized neuropsychological tests were used to assess cognitive function. EEG/ERPs were recorded to assess on-line electrocortical correlates of sensory-cortical processing and selective attention. GH secretion was significantly correlated with target detections and speed of responding in the selection-potential task. Furthermore, GH peak was significantly correlated with the performance letter-digit span test. The present data confirm that cognitive performance in elderly males is associated with GH secretion, with respect to target detection and speed of responding in conditions of selective attention, short-term memory, and basic processing speed.

Differences between low and high trait impulsivity are not associated with differences in inhibitory motor control.

OBJECTIVE: The present study investigates whether there is an association between trait impulsivity in the normal population and inhibitory motor control as assessed by the stop task. METHOD: Low- and high-impulsive participants (as assessed by the I7 questionnaire; both groups n = 31) performed the stop task. Differences in performance were analyzed by an independent samples t-test. Furthermore, a short meta-analysis was performed on this study and three previous studies with a similar aim. RESULTS: The low- and high-impulsive groups did not differ on the speed to stop the response (SSRT). However, the meta-analysis revealed that high-impulsives are marginally slower in stopping than low-impulsives (effect size = -0.26, p= 0.06). CONCLUSIONS: There is only minor evidence that impulsivity inthe common population is associated with poor inhibitory motor control.