Results
diarrhoea, OA, fatigue, fever, toxicity, toxicities, tenesmus, proctitis, valvulopathy, atrial fibrillation, cystitis
TRANSIENT ISCHAEMIC ATTACK, PROCTITIS, CHRONIC ISCHAEMIC HEART DISEASE, HAND-FOOT SYNDROME, ATRIAL FIBRILLATION, CYSTITIS
From March 2021 to November 2022, 33 patients were recruited. The median overall treatment time (OTT) was 35 days (range 32–53). Of these 33 patients, one patient withdrew from the study after 3 RT sessions due to cardiac problems unrelated to the ongoing CRT treatment, which required treatment to be interrupted, intensive cardiac care, and resumption of RT after six weeks. The patient was therefore excluded from the study and from this interim analysis.Table 
Patient’s clinical characteristics
MaleFemale18 (56.3)14 (43.7)
0126 (81.3)6 (18.7)Smoking statusYesNot8 (25)24 (75)
HypertensionType 2 diabetesChronic obstructive pulmonary diseaseBenign prostatic hyperplasiaHypothyroidismGlaucomaCardiological comorbidities (valvulopathy, atrial fibrillation, transient ischaemic attack, chronic ischaemic heart disease)13 (40.6)4 (12.5)3 (9.4)4 (12.5)4 (12.5)2 (6.3)4 (12.5)
HighMiddleLow2 (6.3)11 (34.4)19 (59.3)
2344 (12.5)26 (81.3)2 (6.2)
0129 (28.1)16 (50)7 (21.93)
IIIII9 (28.1)23 (71.9)Of the 32 patients treated, 16 (50%) were considered “responders” based on the calculation of the ERI index, while 16 (50%) were considered “non-responders” and were re-planned with a SIB3 treatment plan.In all the latter cases, a daily OA approach was applied, from the eleventh treatment fraction onwards.Out of a total of 800 delivered fractions, 209 (26.3%) were delivered with such OA modality.Considering the first two weeks of treatment, overall 13/32 (40.6%) patients reported toxicity: 11 patients (34.4%) developed G1 toxicity (6 (18.8%) responders and 5 (25.6%) non-responders), while only 2 patients (6.3%) (1 of each category) developed G2 toxicity.As for the overall toxicity distribution, 30/32 (93.8%) patients developed toxicity of any grade during CRT, of which 22/32 (68.8%) G1, 7/32 (21.9%) G2 and only one patient (3.2%) G3. These differences were not significant between the two groups using the Mann-Whitney U test (p = 0.54).No G4-G5 toxicities were reported (Table 
Distribution of toxicities for different grades in the two different study arms. *p value is referred to Mann-Whitney U testG122 (68.8)G27 (21.9)G31 (3.2)Total30 (93.8)Overall, the most common acute toxicities were diarrhoea 15/32 (46.9%), mucorrhoea 18/32 (56.3%) and tenesmus 14/32 (43.9%), followed by proctitis 9/32 (28.3%), cystitis 9/32 (28.3%) and fatigue 8/32 (25%). No haematological or other toxicity have been reported.As shown in Table Figure 
Trend of acute toxicities during chemoradiation treatment. On the x-axis, points 1 to 4 represent the clinical visits during treatment, every 7 RT fractions. Point 5 represents the clinical visit 45 days after the end of treatment. On the y-axis, the number of patients is displayed. R: responders; NR: non-respondersCRT treatment was discontinued in 5 (15.6%) patients for a median of 2 days (range 1–13) due to linac failure in 2 cases, G3 toxicity in 1 case, onset of fever which resolved spontaneously in 1 case, and inability of the patient to come to the hospital for treatment in 1 case; furthermore, CHT was discontinued in 2 other patients (overall 7 (21.9%)) due to the onset of hand-foot syndrome, with no differences between the two arms.