Noelle O'Rourke

SYSTEMS-2: A randomised phase II study of radiotherapy dose escalation for pain control in malignant pleural mesothelioma

Highlights • A randomised phase II trial of radiotherapy dose escalation for pain control in MPM.• Comparison of 2 hypofractionated regimes (20 Gy/5# and 36 Gy/6#).• Highly conformal radiotherapy techniques used to aid safe dose escalation.• Primary outcome: pain control at week 5 at radiotherapy site.• Recruitment target: 112 patients from 10 to 15 UK centres.

PO-0667: Cardiac toxicity in lung cancer patients after chemo-radiotherapy (CART): a pilot study

Purpose/Objective: To determine if a weekly cone-beam CT (CBCT) is enough to evaluate the entire tumor inclusion and the reproducibility throughout the radiation course treatment in lung cancer. Materials and Methods: Thirty-six lung cancer patients were treated with image-guided radiotherapy (IGRT) on an Elekta Synergy Beam Modulator linear accelerator. The GTV included the tumor and the positive nodes in PET-CT and pathologic analysis. The PTV was configured with the GTV and a margin of 0.7 cm – 1 cm in all directions. In our protocol of lung cancer treatment, prior to each radiotherapy fraction we make one cone-beam CT every day on the first five days of treatment using automated softtissue registration. The positional errors of the reference image in relation to the acquired image (given in terms of translation movements) were obtained. No rotations were permitted. The average of these translational movements in the three axes (x, y, z) was calculated. This average was applied from the sixth day of treatment until the end. Weekly image guidance was registered resulting in at least 10 CBCT scans for each patient. The deviations in the three axes in every weekly CBCT with respect to the average were analyzed (Tx, Ty, Tz) Results: The graphics summarize the result of our analysis. In 29 patients (80.6%) the mean value of the difference between the positional errors compared to the average was: x = (0.19 ± 0.14) cm, y = (0.21 ± 0.14) cm, z = (0.27 ± 0.16) cm. All these values were less than 0.5cm and were considered correct for the suitable treatment of the patients. The shifts in the z axis showed more variability compared to the other axes mainly related to breathing movements. Nevertheless this z axis variability did not influence on the entire tumor inclusion and the set up reproducibility. In the other 7 patients (19.4%) we obtained a greater difference in either axes, and a CBCT more often than once a week was evaluated by the physician. Conclusions: Our preliminary results showed that in most lung cancer patients treated with IGRT, once an average is calculated after the first five days of treatment, a weekly cone-beam CT is enough to evaluate the entire tumor inclusion and the reproducibility throughout the radiation treatment.