Results: Outcomes from 594 patients with 594 UMs were used to create time-dose-response models. The prescribed doses and the number of patients were as follows: 17 to 19 Gy (24 patients), 20 Gy (122 patients), 21 Gy (442 patients), and 22 Gy (6 patients). Averaged over all patients and doses, LC rates at 2, 4, and 7 years were 94.4%, 88.2%, and 69.0%, respectively. Time-dose-response models for LC demonstrated a dose-dependent effect, showing 2-year LC rates of more than 90% with 20 Gy and 95% with 22 Gy. For 4 years and a LC of 90%, a dose of approximately 21 Gy was required. After 7 years, the 21 Gy prescription dose was predicted to maintain a LC above 70%, sharply declining to less than 60% LC with 19 Gy and less than 40% with 18 Gy.

Results: Fifty-four patients were randomized; HFSRT n = 27, WBRT n = 27. HFSRT provided 3-year LC of 96% with similar IC and OS between groups, as reported previously. Median baseline HVLT-R score was 24.0 (Q1-Q3: 18-27) in the HFSRT-group vs. 26.0 (Q1-Q3: 22-28) in the WBRT-group for TR subscale and 8.0 (Q1-Q3: 5-10, HFSRT-group) vs. 9.5 (Q1-Q3: 8-12, WBRT-group) for DR subscale. A drop of =5 points from baseline occurred in 5 patients (18.5%) in the HFSRT-group vs. 8 patients (29.6%) in the WBRT group (risk difference 0.11, 95%-CI [-0.34;0.12], p=0.34). Maximum change in median HVLT-R TR score was +8.3% (Q1-Q3: 23-34, HFSRT-group) vs. -11.5% (Q1-Q3: 18-28, WBRT-group) at 31 weeks from baseline (p=0.079). At no timepoint did the median HVLT-R TR score decline from baseline in the HFSRT-group. For DR subscale, median change from baseline was +17.6% (Q1-Q3: 8-12, HFSRT-group) vs. -15.8% (Q1-Q3: 4-10, WBRT-group) at 31 weeks (p=0.246). Overall hr-QoL (QLQ-C15 PAL) was similar in both groups. Regarding functional subscales, in the WBRT-group a relevant increase in nausea/vomiting (mean +33.3, standard deviation (SD) 13.4 points, p=0.001) and appetite loss (mean +40.3, SD 32.6 points, p<0.001) was observed 7 weeks from baseline with no respective change in the HFSRT-group. The other functional scales of QLQ-C15 PAL and BN-20 were not relevantly different between groups. 

Results:

Cohort characteristics are depicted in Table 1.

Table 1: Clinical and treatment characteristics

Results: From September 2020 to September 2023, 21 patients underwent multisession radiosurgery (mRS) for pituitary adenomas. All patients received a total dose of 25 Gy delivered in 5 fractions over 5 consecutive days. At the time of treatment, the average age was 52 years (range 20-74 years, median 55 years).

The treated lesions had a mean volume of 10 cc (range 0.5-33 cc, median 6 cc). The mean value of the maximum point dose to the chiasm varied from 6 to 32 Gy. The mean value of the maxiumum and the mean doses to the pituitary gland, when identifiable, were 24 Gy (range 14-31 Gy) and 19 Gy (range 6-28 Gy), respectively.

Following a mean follow-up period of 32 months (range 6-36 months), 1 patient experienced transient dysphagia and dysphonia, which was successfully treated with low-dose oral dexamethasone, and 4 patients required minor adjustments in their substitutive hormonal therapy. Overall, visual function was generally maintained, and none of the treated tumors showed progression during the follow-up period.

Results:

56 patients with AVM volume less than 10 cm3 underwent CKRS in Huashan Hosptial. The follow-up time ranged from 36 to 120 months, with median time of 78 months. The prescription dose was 21Gy-22 Gy in 2 fractions or 21Gy – 22.5 Gy in 3 fractions according to AVM volume. A maximum dose to the corticospinal tract of equal to or less than 21 Gy in 3 fractions or 18 Gy in 2 fractions did not cause new neurological deficits. Total obliteration rates were 72% at more than 3 years after one stage or two stage CKRS. One patient had small intracranial hemorrhage 3 years post obliteration. Mild complications were observed in 6 patients because of brain edema, which was required medication.

Results: The mean age was 40 (10-78); 17 cases were male, and five were female. The mean follow-up was 22 months. Five cases (23%) had diffuse, and 17 (77%) had circumscribed angioma. Four cases (18%) had peripapillary, and the others had macular lesions. Before treatment, all cases had subretinal fluid (SRF) causing visual deterioration. Nine cases (41%) had serous retinal detachments; mean basal diameter (BD) was 8.6 (5-14) mm, and tumour thickness (TT) was 3.7 (2.5-7) mm. The median radiation dose was 15  (14-18) Gy. After SRS, mean BD regressed to 5.6 (3-9) mm and TT to 1.7 (0.5-4) mm. SRF disappeared in 18 cases (82%) and decreased significantly in the remaining 4 cases. Visual acuity improved in 21 cases (95%) and stayed stable in one case; the mean increase was 5 + 3.3 Snellen lines. In subgroup analysis, tumours greater than 3.7 mm in thickness had significantly more Snellen line increases than those < 3.7 mm (p=0.023). Patients younger than 40 showed a significantly higher rise in Snellen visual acuity than older cases (p=0.001). None of our patients developed radiation retinopathy or radiation-related complications during the follow-up.

Results:

575 TN patients have been treated at CDI with frameless LINAC radiosurgery. 482 patients (83,8%) required a single treatment to achieve long-term pain control while 93 patients (16,2%) underwent retreatment for resistant or recurrent trigeminal pain. The retreatment group includes 48 men and 45 women, Pain was right-sided in 54 and left-sided in 39. Mean age was 61,3 years (range 29-89). 15 patients (16,1%) had no response to the first treatment (resistant pain) and were retreated within six months. 25 patients (26,9 %) had recurrent pain after a short interval of well-being and were retreated within 12 months. 53 patients (57%) were retreated for recurrent pain at later time (12 to 136 months). Mean interval between first and second treatment was 24,2 months (range 4-136 months). Three patients required a third treatment. Two patients with multiple sclerosis had recurrent pain on the other side and required bilateral treatment( not a retreatment on the same nerve). Mean dose delivered at the first treatment was 58,5 Gy (range; 30-75 Gy), prescribed to a mean 82,6% isodose (range 77-89). Mean dose delivered at the second treatment was 45,3 Gy (range: 30-63 Gy), prescribed to a mean 83,2% isodose (range:79-89). Mean treatment volume at the first treatment was 28,8 mm³ (range: 9-55). Mean treatment volume at the second treatment was 25,1 mm³ (range: 8-44,4). One year after the second treatment satisfactory pain control was achieved in 85 out of 93 pts (91.4%). This pain control rate remained stable after 3 and 5 years. Sensory complications appeared in 27 patients out of 93 (29,3%) after 1 year. Somewhat bothersome facial numbness (BNI grade III) was found in 18 retreated patients (19,4%) while very bothersome facial numbness (BNI grade IV) developed in 3 patients (3,2%).

Results: The sCTs and sDRRs displayed similar visualizations compared to their corresponding CT and DRR counterparts, although exhibiting decreased contrast (see Figure 1). The mean Dice coefficient and SSIM index between the DRRs and sDDRs were 0.96 ± 0.1% and 0.91 ± 0.4%, respectively. The mean difference in the target volume covered with the prescribed isodose surface was found equal to 4.3% ± 4.8%. Moreover, the mean difference in the maximum dose to the brainstem and mean dose to the ipsilateral cochlea were found equal to 3.4% ± 8.7% and 4.3% ± 4.8%, respectively. The observed differences could be attributed to the absence of imaging data in the oral cavity in the MRI images, and therefore in the sCTs, that is included in the CTs and DRRs, as well as to the reduced contrast of the sCTs affecting the effective path length calculations.

Results:

CI and DGI median values were respectively 1.09 (0.96-2.23) and 84.77 (range 19.62-108). DGI as a function of PTV volume is shown in figure 1. A strong significant correlation (p<0.0001) was found between PTV size and DGI with Pearson’s r= -0.78 (95% Confidence Interval: -0.82 to -0.73). DGI ideal values were 95, 82, 77, 71, 59 and 52 for group I, II, III, IV, V and VI respectively. The corresponding minimal DGI values were 86, 73, 67, 59, 43, 36. The rate of DGI passing the minimal criteria was about 90% independently of the group. Considering each center separately, the passing rate with respect to the multicenter Minimal values, ranged from 43% to 100% over the six groups. The inter-institute variability of DGI, expressed in terms of standard deviation, increased with target volume from 6.7 for group I to 12.47 for group VI. Restricting to plans with CI<1.2 (n=220), ideal DGI values remain within 1.4% of the values calculated over all cases. Radii of volumes included in 100%, 85%, 50% and 30% isodose lines are shown in figure 2 as a function of PTV radius together with the R2 values for the corresponding linear regression models. The linear fitting showed a good accuracy. R2 ranged from 0.958 (30% isodose) to 0.994 (100% isodose). When considering only plans with CI<1.20, R2 values increased uniformly (0.966-0.997).

S3585 Physics – Dose prediction, optimisation and applications of photon and electron planning ESTRO 2024

Results: The patient motion-induced shift of lesions has a range of [0.4, 2.3]mm (mean: 1.2+/-0.40mm, based on a 50% likelihood threshold). The Rx dose coverage for each lesion changed from average 99.7+/-0.48% (range: 98% – 100%) to 89.2+/-10.24% (range: 54.5% – 100%). The loss of target coverage is associated with the target distance to the treatment isocenter, and small-sized lesion is more sensitive to intra-fraction motion regarding dose coverage change.

Results: 73 patients were identified who had undergone SBRT pelvic reirradiation: 8 patients received 2 courses of SBRT (4 receiving contemporaneous SBRT to 2 treatment sites, 4 receiving sequential SBRT due to disease progression following first SBRT course).  Treatment data is included in Table 1.

Median OS was 43.5 months (95% CI 33.8 to 69.9 months) (Figure 1). Median PFS was 12.9 months (95% CI 7.9 to 19.5 months) (Figure 2) and median time to local failure of treated lesion was 35.7 months (95% CI 24.7 months to not reached). For cervix versus uterine cancer relapse the median OS was 36.6 months (95% CI 19.7 months to not reached) versus 69.9 months (95% CI 38.6 months to not reached), median PFS was 7.4 months (95% CI 3.6 – 35.7 months) versus 16.1 months (95% CI 10.7 to 30.2 months). Time from primary radiotherapy (r = 0.74) but not GTV/CTV volume (r = 0.25) correlated with longer time to treatment failure. SBRT reirradiation was well tolerated with acute G3 toxicity reported in 2 patients (1x diarrhoea, 1x fatigue). Late G3 toxicity was documented in 2 patients (1x Nausea, 1x Vaginal Stricture), occurring >2 years after treatment.

Results: The HT SFRT plan chosen the combination of FW=5.084 cm, Pitch=0.5 and MF=2.0. A significant decrease in cell viability was observed in HT SFRT with an 8-Gy dose, compared to the CHT. In delivery time, the HT SFRT outperformed SBRT (15.10 minutes vs. 26.43 minutes, p<0.05). In total time, both HT SFRT and SBRT have the significant advantages. For D_max, D_mean, D_median, and D_2% of PTV, HT SFRT in 3 fractions and SBRT was lower than CHT, but HT SFRT in 4 fractions has higher metrics. For bladder and bladder wall, the D_15cc, D_mean and D_max of HT SFRT and SBRT were less than CHT. There were similar values for colon, small intestine and spinal cord between HT SFRT in 4 fractions and CHT. The dose metrics of rectum and femoral head from HT SFRT in 4 fractions were higher than CHT, but this phenomenon can be changed by tightening dose constraints. TCP reached 99.91%-100.00% in all schemes. NTCP of bladder and bladder wall from HT SFRT in 4 fractions was better than CHT, and the two schemes were similar for NTCP of the rectum, colon, and small bowel. But, NTCP of femoral head was greater in HT SFRT with 4 fractions and the phenomenon was also flipped by tightening dose constraints.

Results: With a median follow-up of 12 years, 95% CI [10-14], 19 patients (76%) were in remission, 1 patient had a controlled axillary lymph node relapse (4%)and 5 patients (20%) died due to metastatic progression within a median of 5 years after treatment (min: 1, max: 9). Nine patients (36%) had a complete histological response (pCR). The highest percentage of pCR was in the group of patients treated in the 4th stage (28.5 Gy in 4 fractions). Overall survival at 14 years was 71%, 95% CI [53%-94%]. Two patients developed chronic radiation toxicity during follow-up with a fibrosis (8%), of which one was in the 4th stage and one in the 5th stage (31.5 Gy). Three patients (12%) had a change of prosthesis after treatment which for one patient was 24 months after the end of support.

Results: Median follow-up was 38.6 (4.8 – 65.5)months(m). All pts were evaluable for acute toxicity. Late toxicity and cosmesis data were available for 251 pts. Acute and late toxicity are summarized in Table1. Only 3 pts experienced ≥ G3 acute toxicity and only 1≥ G3 late toxicity. Cosmetic outcome according Harvard breast cosmesis scale was available for 241 pts: excellent 41.5%, good 47.5%, fair 8%, poor 3%. Fourty pts (16%) had liponecrosis, evaluated by mammography, ultrasound or MRI. At the last follow-up cardiac events were diagnosed in 4 pts (3 cases of Trastuzumab-induced pericarditis and 1 case of post-CHT heart failure) and lung fibrosis with symptomatic pneumonitis in 2 cases. Raw local control was 98.8%. Only 3 pts (1.2%) had LR(1 TN, 1 Luminal B HER2+, 1 Luminal B HER2-) and 5 pts(2%) (3 Luminal B HER2-, 1 TN, 1 Luminal A), had distant progression(4 bone metastasis, 1 axillar lymph node), at median TTP of 38.4(22.8-44.5) m. Four pts were dead at the last follow-up (2 old age, 1 comorbidity, 1 metastatic lung tumor diagnosed 21m after RT). Median OS was 44.5 (8.9-73.9) m.

Results: In all patients, the treatments were successfully completed, and the dose prescriptions and dose limits were observed. Median follow-up time was 48 months (range:11-60 months). During the follow-up, we did not detect any local or regional recurrence or distant metastases. Acute side effects included Grade 1 (G1) erythema, which occurred in 8 (11.2%) patients, while G1 oedema was observed in 7 (9.8%) cases. G1 pain was reported by 1 (1.4 %) patient. Late side effects included G1 fibrosis in 11 (15.5%), G1 pain in 4 (5.6%) patients respectively. Asymptomatic (G1) fat necrosis occurred in 8 (11.2%) patients. Cosmetic outcome was excellent in 44 (61.9%), good in 24 (33.9%), and fair in 3 (4.2%) patients. No grade 1-2 acute or late side-effect was detected.

Results: The SGRT system maintained adequate surface coverage and an accurate DIBH-signal at depths averaging 33 cm and 42 cm beyond the treatment iso-center during constant couch speed. Due to the steeper angle of the patient scanned inside the bore and loss of surface images from the two side cameras, effects of occlusion in the clavicular and neck regions were observed for all volunteers. The surface coverage was also influenced by the longitudinal and vertical couch positions within the gantry, the gantry geometry, and patient morphology (Figure 1). Accurate detection of the simulated respiratory motion using the HexaMotion platform was obtained for all cases by the Catalyst⁺HD^TM system during constant couch speed. Significant difference in the dose to the heart and left anterior descending artery (LAD) was found between the DIBH and FB plans as the DIBH plans offered a median (range) average dose reduction up to 27% (13-33%) and 40% (26-49%) (p <0.001) to the heart and LAD respectively. As for the near-maximum dose (D2%) to the heart and LAD, the median (range) dose reduction was 50.0% (47-58%) and 47.0% (42-56%) (p <0.001), respectively. No significant difference between DIBH and FB was observed in the average dose to the PTV and ipsilateral lung, nor in the conformity and homogeneity indices.

Results: The whole sample included 66 treatment plans, 39 performed using TD (26 with 42.4 Gy/16 fx and 13 with 50 Gy/25 fx) and 27 using TH (11 with 42.4 Gy/16 fx, 16 with 50 Gy/25 fx). The TD plans had a mean beam on time of 168.8±26.5 sec, while TH were about 400.6±74.7 sec, with an average gantry period of 17.2±3.5 sec. On the average, mean dose covering the planning target volume (PTV) was 99.4% for TD and 99.9% for TH, V 95%=96.1±1.7% and 95.9±1.4%, with V107%=0.2±0.3 cc and 0.4±1.1 cc for TD and TH, respectively. Regarding dose to the OARs, detailed results are described in table 1, reported as average and standard deviation.

Briefly, the heart mean doses, for the two fractionations 42.4 Gy/50 Gy, were 1.0±0.5/1.1±0.4 Gy and 1.7±0.7/2.0±0.7 Gy for TD and TH respectively, resulting comparable with the DIBH values reported in the recent meta-analysis [3], ranging between 0.9 and 2.7 Gy. Similarly, for ipsilateral lung the mean dose was 4.4±1.1/5.2±0.9 Gy and 5.1±0.6/5.3±0.9 Gy for TD and TH respectively, that is included in the range of DIBH for the left lung (0.59-14.9 Gy).

Also for LAD, the mean values were 4.3±3.7/5.0±3.5 Gy and 5.0±1.4/4.7±1.9 Gy for TD and TH respectively, that falls within the reported range (0.4-9.4 Gy). Results were also comparable in terms of near maximum dose (D 0.03cc).

Results: A total of 14 patients with a median age at enrollment of 66.8 years (IQR 63.4 – 69.0) were treated within the study. Nine of them have been enrolled and treated within the phase I of the study (3 patients for each dose step: 18-21 24 Gy) while five were treated within the phase II with 24 Gy in single fraction. Stage at diagnosis was T1N0 for nine patients and T2N0 for 5 patients (luminal A for 10 patients, luminal B for 1 patient, luminal B-HER2+ for 2 patient and triple negative histology for 1 patient). Median PTV volume was 15.1 cm3 (range 3.6-47.8 cm3). At pre-surgery MRI 7 patients experienced stability disease, 4 patients a partial response and one patient a complete response, with a median disease extension reduction of 17.9%. Median time to surgery was 33 days (range 28 – 40 days) with 3 patients who underwent mastectomy and 11 QUAD+BLS. One post-surgical complications (liponecrosis) has been reported. All patients except one experienced a reduction in Ki67 proliferation index (median change between biopsy and histologic exam of 7%). Eleven among the 14 treated patients have received post-operative RT according to study protocol, with two patients receiving also chemotherapy. No G>2 acute toxicities have been reported and only one G1 chronic toxicity (breast pain) has been reported at last follow-up. 1-year follow-up was available for 9 out of 14 patients. At a medium follow up of 13.1 months (range 1.4 – 23.3 months) two patients developed a regional relapse and two patients a second tumor in another site. All the other patients are alive with no evidence of disease.

Results: A total of 146 patients were finally enrolled from July 27, 2018 to November 1, 2021 . Seventy-three patients each were assigned to the experimental group and control group. The median follow-up was 46 months. The 3-year OS was 58.36% in the Hypo-RT versus 38.39% in the Con-RT (P = 0. 02). The median OS from randomization was 41 months in the Hypo-RT group and 30 months in the Con-RT group (HR, 0.61; 95% CI, 0.395–0.939; P = 0. 022). No significant differences in grade 2 or greater TRAEs were found between the two groups.

Results: FW could impact the dose distribution for both the target volume and OARs, particularly for homogeneity, right lung, liver, and esophagus. Meanwhile, FW emerged as the most influential parameter affecting treatment time, resulting in a significant average time reduction of more than half. A tighter PF could slightly reduce OARs dose, especially for the left lung, sum of lung, and liver without increasing the treatment time. MF could impact the dose distribution, especially for the lung. But no obvious differences were observed for CI an HI under varied MFs conditions. The treatment time increased gradually with the rise in MFs, but the increase was modest. After thoracic radiation, three patients archived partial response and on patient with stable disease at 6 months. No severe lung toxicities could be observed in these four patients.

Results: Among a total of 230 lesions (118 right sided and 112 left sided) we found 10 lesions with volumes overlap -6 pts-(equally divided between right and left), 3 of which belong to a single patient and categorized those cases as re-RT type 1 group. Among this group, median re-RT dose was 50Gy (range 32.5-55) delivered in 5 fractions. Treatment was delivered every other day and prescribed at 80% isodose-line. Time interval between re-RT was at least 6 months with a maximum of almost 3 years. Primary was lower gastro-intestinal (GI) tumour in 3 pts, lung tumour in 2 pts and hepatocarcinoma (HCC) in one pt. Two re-irradiated targets were centrally located. All pts well tolerated SBRT with CK and none of them experienced severe toxicity (in particular no fatal bronchial bleeding and/or fistulae were recorded in central targets). One of the 2 pts with centrally located target reported onset of cough (grade 1) few weeks after re-RT.

Results: Of the 68 eligible patients, median age was 73 yrs (range 50-90). Non-small cell lung cancer was the most prominent primary tumour (n=62), followed by colorectal (n=8), cervix (n=1), and renal (n=1). The median tumour volume reached 12.40cc (ranging from 1.24 to 77.30cc). The median maximum dose (Dmax 0.5cc) to the trachea and bronchus was recorded to be 23.2Gy (0.7-59.5Gy range). The median follow-up period lasted 16 months (spanning from 1-67), with a projected median OS of 39 months and an OS at the 12-month mark of 82%. Recorded toxicity rates remained low, with grade 1 toxicity including fatigue and grade 2 comprising of cough and dyspnoea.  

Results: 125 patients were included: 79 (63%) were male and median age at treatment was 69 (range 22-94) years. The median number of previous treatment lines was 1 (range 0-11). Indolent B-cell, diffuse large B-cell and T-cell histology were detected in 24%, 22% and 42% of the patients respectively. Before treatment, 45% of the patients had local skin symptoms such as itching, pain or ulceration in the treated site. RT was delivered with HT in 74% and with LINAC in 26% of patients. Median prescribed dose was 30 Gy (range 4-50 Gy), delivered in daily fractions of 2 Gy (range 1.6-8 Gy) to a median PTV volume of 488 cc (range 7-7871 cc). ORR at 1 month was 97% (61% CR and 36% PR). Acute skin AEs of any grade (G>=1) were detected in 73%, G>=2 events in 22% and G3 events only in 3% of patients. No G4-5 events were observed (Table). Total RT dose >30 Gy was related with higher risk of developing any grade AE (85% vs 54%, p700 cc was related with higher risk of G>=2 AEs (34% vs 16%, p = 0.03). Daily RT dose had no impact on acute AEs. With a median follow-up of 15 months, 1-year LC and PFS were 84% and 60%, respectively (Figure). On MVA, PTV volume >700 cc had a negative impact on LC (HR=5.48; p=0.01). The presence of skin symptoms before RT (HR=2.90; p=0.003), T-cell histology (HR=1.59; p=0.04) and again PTV volume >700 cc (HR=2.90; p=0.003) negatively affected PFS. The prescribed RT dose did not affect neither LC nor PFS.

Results: 74 patients (AML n=56, ALL n=18) were treated from 5/2014-9/2020. Median age was 40.1 (16.5 – 59.3) years. 51 (69%) patients were induction failures. 72 (97%) patients had detectable marrow blasts and 36 (49%) detectable circulating blasts just prior to TMLI. The day+30 BM biopsy CR rate was 92%. Engraftment occurred for all subjects. Mean organ doses (Gy) were lung 8.8, kidneys 7.3, heart 7.5, thyroid 8.0, lens 2.5 and lower GI 10.2. Grade =2 Bearman scale toxicities were stomatitis (Gr2 n=17, Gr3 n=5), gastrointestinal (Gr2 n=10, Gr3 n=4), renal (Gr2 n=1, Gr3 n=5), hepatic (Gr2 n=3, Gr3 n=2), central nervous system (Gr2 n=3, Gr3 n=1), bladder (Gr2 n=4), pulmonary (Gr2 n=1), and cardiac (Gr2 n=1). Median follow-up was 1.8 years (range: 0.1-5.9) and for surviving patients 4.2 years (range: 2.0-5.9). The 2-year PFS and 2-year OS were 31.1% (95%CI: 21%-42%) and 45.9% (95%CI: 34%-57%). The cumulative incidence of NRM at day+100, year 1, and year 2 were 4.1% (95%CI: 1-10%), 8.1% (95%CI: 3-16%), and 12% (95%CI: 6-21%), respectively. Peripheral blasts = 20% prior to TMLI was associated with higher risk of disease relapse/progression or death.

Results: 874 pts were randomized from 38 centers (n=441 (CRT) and n=433 (SBRT)) between 08/2012 and 01/2018. Baseline characteristics were well balanced across CRT and SBRT groups: median age 69.8 years (IQR 65.4,74.0); median PSA ng/mL (IQR): 8.1 (6.3,11) vs 7.9 (5.5,10.9); NCCN risk group 9.3% low, 90.7% intermediate. With median follow-up of 73.1 months (IQR 62.6, 84.0), 5-year BCF event free-rate (95% CI) was 94.6% (91.9% – 96.4%) vs 95.7% (93.2% – 97.3%) for CRT and SBRT groups respectively. SBRT was non inferior to CRT with unadjusted HR (90% CI) = 0.74 (0.47 – 1.17), p-value for non-inferiority=0.007. The estimated absolute differences in the proportion of patients event free in the SBRT group compared with that in the CRT group at 5 years was: 1.36% (90% CI: 0.87 – 2.80). At 5 years, RTOG grade 2 or worst (G2+) genitourinary toxicity was seen in 3.2% (11/348) pts who received CRT and 5.5% (20/363) pts who received SBRT (p=0.14); RTOG G2+gastrointestinal toxicity was seen in 1/348 receiving CRT and 1/363 received SBRT (p=0.99).

Results: Of the 12 completed treatments analysed, 11/12 were considered successful. One simulated treatment was considered unsuccessful as two out of the six fractions exhibited underdosage of the SV on the post-fraction CT scan. For both fractions, bladder volumes increased substantially (<200 mL pre-fraction to >800 mL post-fraction) resulting in a large posterior/caudal displacement of the SV and subsequently SV V95 of 78.2% and 84.9%, respectively. Of the remaining 11 treatments (consisting of 66 fractions), only two fractions of different patients exhibited SV underdosage on the post-fraction CT-scan. One fraction showed an anterior/cranial displacement of the SV caused by an intrafraction large rectal gas pocket, whereas the second fraction exhibited a posterior/caudal displacement of the SV due to an intrafraction bladder volume increase.

Comparing adaptation to the non-adapted treatment plan, an improvement in the population average SV V95 on the post-fraction CT-scan from 97.6% to 99.3% (aim ≥ 99%) was seen, as well as a slight improvement of the OAR dosimetrics, within the constraints. However, on an individual patient level, adaptation resulted in only one unsuccessful treatment compared to four using non-adapted plans. Looking at the individual fractions, adaptation resulted in a total of only four fractions with SV underdosage compared to a total of 18 fractions for the non adapted plans. Furthermore, the adapted plans resulted in OAR doses adhering to the OAR constraints for 13 of the fractions in which the non-adapted plans did not adhere to the constraints.

Regarding GU and GI toxicity none out of 12 patients reported toxicity more than grade 1. See figure 1 for a detailed bar chart regarding toxicity scores for all patients.

Results: Between July 2013 and March 2023, 20 participants were enrolled on the study with a median follow-up of 30 months. The median D95 dose to DIL was 47.43Gy. Cumulative acute grade 2 and above genitourinary (GU) and gastrointestinal (GI) toxicity was 25% and 30%, respectively. One patient developed acute grade 3 GU toxicity (5%).

By week 12 post treatment, all grade 2 or above GU and GI toxicity had resolved. There is no late grade 3 GU or GI toxicity to date. IPSS score and urinary quality of life scores recovered to baseline by 6months. Patient-reported outcomes showed no significant change in EQ-5D quality of life scores at 12 weeks and 1 year compared to baseline. There are no cases of biochemical relapse reported to date.

Results: For the urethra, median (range) D0.03cc was 41.8 Gy (38.9–46.8 Gy) and 41.6 Gy (36.2–46.5 Gy), D0.3cc was 41.0 Gy (38.0–46.0 Gy) and 40.9 Gy (34.3–46.0 Gy), and V40Gy was 0.76 cc (0–4.92 cc) and 0.97 cc (0–6.83 cc) for cohorts A and B, respectively. For the bladder, median (range) D0.03cc was 41.2 Gy (29.1–49.0 Gy) and 41.3 Gy (35.7–46.7 Gy), D5cc was 34.5 Gy (17.2–39.5 Gy) and 34.9 Gy (17.9–38.9 Gy), D10cc was 30.1 Gy (14.4–36.4 Gy) and 30.4 Gy (9.6–36.3 Gy), and V37Gy was 2.4 cc (0–8.3 cc) and 2.7 cc (0–7.8 cc) for cohorts A and B, respectively. No statistically significant differences in these parameters were observed between the two cohorts. Late urinary toxicity of grade 3 or higher occurred in 2.25% of patients in the IPB group, with no grade 3 acute toxicities reported. 

Results: We included 52 patients and performed 55 treatments. The primary tumor was prostate adenocarcinoma in 19 patients (36 %), colorectal in 17 (33%) and 16 patients (31%) had a primary tumor with a different origin. For only 12 patients (22%) plan A was delivered in all fractions and thus received the standard treatment. An adaptive treatment plan was chosen in 58% of the fractions. Plan C was most frequently selected from the library in 45% of the fractions, followed by plan A in 43%. Plan B was chosen in 12% of the fractions. Anatomical variations observed in the fraction CT scan led to replanning for 4 patients, with in 3 cases due to a constraint violation and in 1 patient due to movement of the GTV outside the PTV. A local control of 96% was achieved at 1 year, as shown by the Kaplan Meijer curve displayed in Figure 1. The median overall survival was 49 months (95% CI 39-58). One patient developed a late grade 3 ureter stenosis 2 years after treatment of a left iliacal lymph node. Grade ≤ 2 acute toxicity was reported in 34 patients (62%). Grade ≤2 late toxicity was reported in 4 patients (8%).

Results: Median follow-up was 13.9 (0-61.9) months. Median time between primary tumor diagnosis and SBRT for OMD was 62.2 (0-356.7) months. Median prescribed dose was 30 Gy (16-60) in a median of 3 (1-8) fractions, at a median isodose of 80% (63%-85%). For 47 treatments (48.4%) concomitant systemic therapy was prescribed. Median Biological Equivalent Dose (BED), calculated with tumor specific a/b coefficient of 3, was 146.7 (66.7-378) Gy. OS of all pts at 12- and 24-months was 87.1% and 63.6%, respectively. Twelve- and 24-month LRFS was 81.8% and 78.7%, respectively. At the last follow-up NEST was necessary for 11 pts (25 lesions). Median time to NEST was 8 (1.6-30.8) months. NEST-free survival at 12- and 24-months was 70.7% and 63.2%, respectively. Median NEST-free survival for pts with SBRT only was not reached, and was 30.8 months for pts with SBRT and systemic therapy. Six-, 12- and 24 months NEST-free survival was 85.1%, 82%, and 69% for pts with SBRT only vs 76.5%, 56.6% and 56% for pts with SBRT and systemic therapy (p=0.15), probably due to the selection of pts with more advanced disease for systemic therapy. 

Results: A total of 56 lesions in 40 pts were treated. Median age of the patients at diagnosis was 66 years (29-83). Median follow up was 14.5 months (0.6-81.9). Twenty-five lesions were treated with CK, the remaining 31 with HT. Median number of liver metastases/patient was 4 (1-6). Median GTV was 16.65 (0.3-631.7) cc. Median BED, calculated with tumor specific a/b coefficient, was 100 (59.5-378) Gy. No ≥ G3 toxicities and radiation-induced liver disease (RILD) were recorded. OS at 6- and 12-months of NOMD, ROMD and IOMD were 90%, 84.6%, 80% and 73%, 75.2%, 70% (p=0.4), respectively. Six- and 12-month LRFS for NOMD, ROMD and IOMD was 85.9%, 100%, 100% and 85.9 %, 77.8% and 100%, respectively (p=0.48) (Figure 1). 

Results: Characteristics of the MHRT (608 treated/601 allocated) and SBRT (584/607) groups respectively were: median age: 72.4 vs 73.1 years; NCCN intermediate risk 63.3% vs 64.6%, high risk 36.7% vs 35.4%; Gleason score≤3+4: 62.4% vs 59.9%, 4+3: 30.8% vs 35.6%, 4+4: 6.8% vs 4.5%; PSA median (IQR) 8.3 (6-12.4) vs 8.5 (6-12.4).

RTOG G2+ toxicity was not significantly different for GI events (MHRT 69/606 (11.4%) vs SBRT 75/581 (12.9%), p=0.422; G3+ 3/606 (0.5%) vs 2/581 (0.3%)), nor GU events (MHRT 166/605 (27.4%) vs SBRT 160/579 (27.6%) p=0.94; G3+ 10/605 (1.7%) vs 12/579 (2.1%)). There were differences in CTCAE G2+ GI toxicity: MHRT 60/604 (9.9%) vs SBRT 90/584 (15.4%) p=0.004) but not GU: MHRT 170/604 (28.2%) vs SBRT 194/582 (33.3%) p=0.053. Percentage of pts with MCID for MHRT vs SBRT; UI was 187/511 (36.6%) vs 184/496 (37.1%), p=0.869; UO was 324/493 (65.7%) vs 336/478 (70.3%), p=0.127; bowel was 251/514 (48.8%) vs 287/488 (58.8%), p=0.002