LBA2002 Background: Despite treatment advances, survival of elderly GBM patients (pts) is usually < 12 months. Hypofractionated RT is advocated in order to shorten treatment time, and chemotherapy has been proposed as an alternative to RT. In a randomized trial we compared two different RT schedules with single-agent TMZ chemotherapy. Methods: Newly diagnosed GBM pts age ≥ 60 years with PS 0-2, were randomized to either standard RT (60 Gy in 2 Gy fractions over 6 weeks) or hypofractionated RT (34 Gy in 3,4 Gy fractions over 2 weeks) or 6 cycles of chemotherapy with TMZ (200 mg/m2 day 1-5 every 28 days). Follow-up including quality of life, symptom checklist, and steroid dosing was completed at 6 weeks, 3 months, and 6 months after start of treatment. The primary study end point was overall survival (OS). Results: A total of 342 pts were included. 291 pts were randomized between the 3 treatment options, 51 pts between hypofractionated RT and TMZ. Median age was 70 years (range 60-88), 59% were male and 72% had undergone tumor resection, the remaining 28% had a diagnostic biopsy only. Performance status was 0-1 for 75% of pts. Survival data are available for 334 pts (98%), with 11 pts (3%) being alive. There was no significant difference in OS between the three treatment arms, with median survival being 8 months for TMZ, 7.5 months for hypofractionated RT and 6 months for 6 weeks RT (p=0.14). Conclusions: Elderly patients with GBM have a short survival. Time-consuming therapy that does not offer longer survival should therefore be avoided. Our study showed no advantage of standard 6 weeks RT compared to hypofractionated RT over 2 weeks or 6 cycles of TMZ chemotherapy. These results indicate that standard RT should no longer be offered to the elderly pt population with GBM. Exclusive TMZ chemotherapy may be an alternative to RT. Subgroup analyses and determination of molecular markers is ongoing. Whether outcome could be improved by concomitant chemoradiotherapy is subject of ongoing clinical trials. [Table: see text]

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Objective: This study aimed to investigate the tumor volume changes occurring during limited-field radiotherapy (RT) for glioblastoma patients and whether a volume-adapted boost planning approach provided any benefit on tumor coverage and normal tissue sparing. Meterials and Methods: Twenty-four patients underwent simulation with magnetic resonance (MR) and computed tomography (CT) scans prior to RT (MR_initial, CT_initial) and boost treatment (MR_adapt, CT_adapt). For the boost phase, MR_initial and MR_adapt images were used to delineate GTV2 and GTV2_adapt, respectively. An initial boost plan (Plan_initial) created on CT_initial for PTV2 was then reoptimized on CT_adapt by keeping the same optimization and normalization values. Plan_adapt was generated on CT_adapt for PTV2_adapt volume. Dose volume histogram parameters for target volumes and organs-at-risk were compared using these boost plans generated on CT_adapt. Plan_initial and Plan_adaptive boost plans were summed with the first phase plan and the effect on the total dose was investigated. Results: Target volume expansion was noted in 21% of patients while 79% had shrinkage. The average difference for the initial and adaptive gross tumor volume (GTV), clinical target volume (CTV), and planning target volume (PTV) volumes were statistically significant. Maximum dose differences for brainstem and optic chiasm were significant. Healthy brain tissue V10 and ipsilateral optic nerve maximum doses were found to decrease significantly in Plan_adaptive.Conclusion: Results of this study confirm occurrence of target volume changes during RT for glioblastoma patients. An adaptive plan can provide better normal tissue sparing for patients with lesion shrinkage and avoid undercoverage of treatment volumes in case of target volume expansion especially when limited-fields are used.

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Colorectal cancer is the third most common cancer in Turkey. The current guidelines do not provide sufficient information to cover all aspects of the management of rectal cancer. Although treatment has been standardized in terms of the basic principles of neoadjuvant, surgical, and adjuvant therapy, uncertainties in the management of rectal cancer may lead to significant differences in clinical practice. In order to clarify these uncertainties, a consensus program was constructed with the participation of the physicians from the Acıbadem Mehmet Ali Aydınlar and Koç Universities. This program included the physicians from the departments of general surgery, gastroenterology, pathology, radiology, nuclear medicine, medical oncology, radiation oncology, and medical genetics. The gray zones in the management of rectal cancer were determined by reviewing the evidence-based data and current guidelines before the meeting. Topics to be discussed consisted of diagnosis, staging, surgical treatment for the primary disease, use of neoadjuvant and adjuvant treatment, management of recurrent disease, screening, follow-up, and genetic counseling. All those topics were discussed under supervision of a presenter and a chair with active participation of related physicians. The consensus text was structured by centralizing the decisions based on the existing data.