F. Zerbetto

Higher-than-expected Severe (Grade 3–4) Late Urinary Toxicity After Postprostatectomy Hypofractionated Radiotherapy: A Single-institution Analysis of 1176 Patients

BACKGROUND Dose escalation and hypofractionation may have a role in postprostatectomy radiotherapy (RT), but at the risk of increasing urinary toxicity. OBJECTIVE To address predictors of severe (Grade ≥3) late urinary toxicities (LGUTOX3) after postoperative irradiation. DESIGN, SETTING, AND PARTICIPANTS A single-institution cohort of 1176 patients treated between 1993 and 2010 with adjuvant or salvage RT was analyzed. A total of 929 patients underwent conventionally fractionated (CF) RT (1.8 Gy per fraction; median dose to the prostatic bed: 70.2 Gy) with nonconformal RT (n=169), three-dimensional conformal RT (n=657), or intensity-modulated RT (n=103) technique, while 247 patients received hypofractionated helical TomoTherapy (median: 2.50 Gy per fraction) at the following doses: 117 patients at 65.8 Gy (2.35 Gy in 28 fractions), 80 patients at a median of 71.4 Gy (2.5-2.6 Gy in 28 fractions), and 50 patients at 58 Gy in 20 fractions. Total doses were converted into 2 Gy-equivalent doses (EQD2) following the linear quadratic model taking α/β=5. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Univariable and multivariable Cox regression models tested the relationship between clinicodosimetric variables and the risk of LGUTOX3 retrospectively, graded according to Common Terminology Criteria for Adverse Events v.4.0. RESULTS AND LIMITATIONS After a median follow-up of 98 mo, the 5-yr risk of LGUTOX3 was 6.9% and 18.1% in the CF and hypofractionated cohorts, respectively. At univariable analysis, the risk of LGUTOX3 was predicted by dose per fraction (hazard ratio [HR]: 2.96), acute Grade ≥2 toxicity (HR: 2.37), EQD2, pT4, and year of irradiation. At multivariable analyses, acute Grade ≥2 toxicity and dose per fraction independently predicted LGUTOX3 in the population, while an interaction analysis indicated a predictive role of hypertension in the hypofractionated cohort only. These findings are limited by their retrospective nature. CONCLUSIONS In the postprostatectomy setting, the logistic convenience of hypofractionation should be carefully balanced against the risk of severe late urinary sequelae. PATIENT SUMMARY This study investigated the causes of urinary adverse effects after postprostatectomy radiotherapy. Hypofractionation resulted in an increased risk of severe urinary toxicities.

Early volume variation of positive lymph nodes assessed by in-room mega voltage CT images predicts risk of loco-regional relapses in head and neck cancer patients treated with intensity-modulated radiotherapy

ABSTRACT Background. We investigated the possibility to early identify non-responding patients based on FDG-PET positive lymph nodes (PNs) volume variation assessed with in-room images. Material and methods. Twenty-seven head and neck cancer patients with at least one pre-treatment PNs were retrospectively analyzed; they received 54 Gy, 66 Gy, 69 Gy in 30 fractions on precautionary lymph nodal (N), primary (T) and PET positive (BTV) planning target volumes (PTVs), respectively with Helical TomoTherapy (SIB approach). PNs volume changes during treatment were assessed based on megavoltage computed tomography (MVCT) used for image guidance as ratio between volumes at fractions 10/20/30 and at first fraction. Data on T, N and M relapses (rT, rN, rM) were collected for all patients. The difference of PNs volume changes, during treatment, between patients with versus without relapses was tested (Mann-Whitney test). The impact of shrinkage on the corresponding survival curves (Cox proportional-hazard regression), dividing between no/moderate versus large shrinkage (based on ROC curve best cut-off value) was also investigated. Results. Median follow-up was 27.4 m (3.7–108.9). The numbers for rT, rN, rM were 5, 4, 6, respectively. Differences in PNs shrinkage were found between patients with and without rT/rN at all considered timing [fr 20, rT: 0.56 vs. 1.07 (median), p = 0.06; rN: 0.57 vs. 1.25, p = 0.07]. Differences were lower for rM. Survival curves provide high hazard ratios (HR) between PNs changes and rT/rN at all considered timing [fr 20, rT: best cut-off = 0.58, HR 5.1 (95% CI 0.5–49.4), p = 0.12; rN: best cut-off = 0.98, HR 14.9 (1.6–142.9), p = 0.01]. Conclusion. A limited shrinkage of PNs during treatment is associated with poorer outcome in terms of T/N relapses. The early variation of PNs observed on in-room images may provide useful information about the individual response with potential application in guiding an early adaptation of the treatment.

18F-FAZA PET/CT Hypoxia Imaging of High-Grade Glioma Before and After Radiotherapy

A 57 year-old man underwent MRI with dynamic susceptibility contrast and dynamic contrast-enhanced perfusion for neurological symptoms suggesting the diagnosis of high-grade glioma. A F-FAZA PET/CT was performed because of the enrollment in a prospective clinical trial. Subsequent radiotherapy treatment has been planned based on conventional imaging; moreover, a F-FAZA PET/CT-guided treatment planning highlighting hypoxic regions has been simulated. After radiotherapy treatment, the man underwent MRI and F-FAZA PET/CT, showing partial response.