change of motion pattern). Based on these findings, additional modelling functionality was added. Afterward, one additional pt was treated with less pauses (Pre-update:8AE6.2, Post:1.6AE1.5). Another pt was attempted, but difficulty identifying the lesion near the diaphragm led to tx being aborted and gating plan being initiated. Among those with follow up (n Z 4, mean:4 mo, R:1-6 mo), no pts displayed any grade 2 or higher toxicities. Conclusion: We report the first RMSTC for helical tomotherapy delivery in pts. Accuracy and safety of tx delivery was confirmed. Early experience has informed workflow. Appropriate pt selection is evolving, further evaluation is needed for lesions near the diaphragm. Additional study and follow up is warranted and planned.

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BACKGROUND Probable unresectable Glioblastomas (GB) diagnosed by imaging techniques withouth anatomo-pathological (ap) confirmation could be treated under standard treatment. We reported the outcomes from this strategy in our center after tumor board evaluation. MATERIAL AND METHODS From January/10 to September/16, 303 patients (pt) with GB were assessed by tumor board, during the same period 66 patients were consecutive analyzed with suspected GB by radiological criteria without histological diagnosis. We focus in the last group and analyzed the demographic/radiological data, non-biopsy causes, treatment type (concomitant Radio-Chemotherapy (RT/Ch), exclusive RT or Ch or Best supportive care (BSC)), Karnofsky index (KI) and degree of comorbidity (Charlson index (CI)). RESULTS Sixty six patients, 17.88% of the total GB cases (with/without ap). Average age: 77 years (33–91). Biopsy: non-diagnostic in 4pt. No biopsy: 62pt; due to non medical indication (71%), localization (22.7%), voluntary (4.5%). Treatment Type: Active: 43.93%, without biopsy due to non-medical indication (44.8%) and localization (41.37%). BSC: 53.03%, without biopsy due to non-medical indication 82.85%, localization 8.5%, voluntary 5.7%. Overall survival: 11.65 months in patients with active treatment and 4.8 months in BSC, greater benefit in <70 years and KI≥ 70 with statistical signification. CONCLUSION The diagnosis of GB by radiological criteria with the new imaging techniques has a good diagnostic-therapeutic correlation. In cases where surgical intervention is not possible, standard treatment offers good results. Age and KPS are variables that allow predicting a better evolution course. Although it was not possible to obtain a histological diagnosis, in this type of cases liquid biopsy could contribute to diagnosis this type of lesions inaccessible to biopsy.