Leila Khouri

Assessment and topographic characterization of locoregional recurrences in head and neck tumours.

PurposeTo evaluate the differences between three methods of classification of recurrences in patients with head and neck tumours treated with Radiation Therapy (RT).Materials and methods367 patients with head and neck tumours were included in the study. Tumour recurrences were delineated in the CT images taken during patient follow-up and deformable registration was used to transfer this volume into the planning CT. The methods used to classify recurrences were: method CTV quantified the intersection volume between the recurrence and the Clinical Target Volume (CTV); method TV quantified the intersection between the Treated Volume and the recurrence (for method CTV and TV, recurrences were classified in-field if more than 95% of their volume were inside the volume of interest, marginal if the intersection was between 20-95% and outfield otherwise); and method COM was based on the position of the Centre Of Mass of the recurrence. A dose assessment in the recurrence volume was also made.ResultsThe 2-year Kaplan-Meier locoregional recurrence incidence was 10%. Tumour recurrences occurred in 22 patients in a mean time of 16.5 ± 9.4 months resulting in 28 recurrence volumes. The percentage of in-field recurrences for methods CTV, TV and COM was 7%, 43% and 50%, respectively. Agreement between the three methods in characterizing individually in-field and marginal recurrences was found only in six cases. Methods CTV and COM agreed in 14. The percentage of outfield recurrences was 29% using all methods. For local recurrences (in-field or marginal to gross disease) the average difference between the prescribed dose and D98% in the recurrence volume was -5.2 ± 3.5% (range: -10.1%-0.9%).ConclusionsThe classification of in-field and marginal recurrences is very dependent on the method used to characterize recurrences. Using methods TV and COM the largest percentage of tumour recurrences occurred in-field in tissues irradiated with high doses.

RESPONSE, an Electronic Health Patient Information Software for Radiation Therapy

RESPONSE, a health information software specific for radiation therapy (RT) has been developed. This tool intends to proactively contribute to improve patient outcome registration, helping the radiation oncologist during the medical consultation, but also to be a tool with research goals.

Semi-supervised Self-training Approaches in Small and Unbalanced Datasets: Application to Xerostomia Radiation Side-Effect

Supervised learning algorithms have been widely used as predictors and applied in a myriad of studies. The accuracy of the classification algorithms is strongly dependent on the existence of large and balanced training sets. The existence of a reduced number of labeled data can deeply affect the use of supervised approaches. In these cases, semi-supervised learning algorithms can be a way to circumvent the problem.

Biological dose-escalated definitive radiation therapy in head and neck cancer

OBJECTIVE To compare treatment outcome of patients with head and neck (HN) tumours treated with definitive radiation therapy that, mainly owing to differences in the fractionation scheme used with simultaneous integrated boost techniques, resulted in a different biological dose. METHODS 181 patients with HN cancer, prescribed to about 70.2 Gy in the primary tumour, were included in this study. Population cohort was divided into Group <70 and Group ≥70 when the mean dose converted to a 2 Gy fractionation in the primary tumour was less or higher than 70.2 Gy, respectively. The probability of local control (LC), locoregional control (LRC), disease-free survival (DFS) and overall survival (OS) was determined for both groups. The incidence of acute and late complications was compared between the two groups. RESULTS At 24 months for Groups <70 and ≥70, LC was 83.2% and 87.5%, LRC was 79.5% and 81.6%, DFS was 56.3% and 66.8% and OS was 63.9% and 71.5% p = ns, respectively. The incidence of acute dysphagia, odynophagia and pain, and late mucositis was significantly higher in Group ≥70 than in Group <70. The rate of xerostomia, dysphonia, radiodermatitis, alopecia, dental complications, hypoacusia and weight loss was comparable between the two groups. CONCLUSION The biological dose escalation was safe, but an increase in the incidence of the acute side effects: dysphagia, odynophagia and pain and late mucositis, was obtained. Advances in knowledge: Despite the significant biological dose escalation, within the range of doses delivered to this cohort, no clear dose-response effect was observed.

EP-1637: Dose plan assessment of coplanar and non-coplanar beam angle optimization algorithms

Material and Methods: Between January 2014 and March 2014, 60 previously irradiated patients with LARC were retrospectively recruited: 40 IMRT plans were selected to configurate the Dose Volume Histogram (DVH) model and to train it. The remaining 20 were firstly manually optimized by 2 medical physicists and then used to validate the model as benchmark plans (BP). OaRs constrains followed Quantec guidelines. Three model based on different PTV objectives have been generated: DVH model 95-105%, DVH model 98105% and DVH model 98-103% where more than 95%, 98% and 98% of the PTV received more than 95% of the prescription dose and less than 5%, 5% and 3% of the PTV received more than 105% of the prescription dose, respectively. The performances of automated plans (one series for each model) vs BP were statistically compared using Wilcoxon signed-rank test, for PTV V95 and V105, hot spot out of PTV (HToPTV), bladder mean dose (BmD) and maximum dose (BMD), bowel mean dose (BomD) and V45 (BV45). Two expert radiotherapists (observer1 and observer2) clinically validated in double blind the IMRT plans.

SU-E-T-399: Determination of the Radiobiological Parameters That Describe the Dose-Response Relations of Xerostomia and Disgeusia From Head and Neck Radiotherapy

PURPOSE To estimate the radiobiological parameters that describe the doseresponse relations of xerostomia and disgeusia from head and neck cancer radiotherapy. To identify the organs that are best correlated with the manifestation of those clinical endpoints. Finally, to evaluate the goodnessof- fit by comparing the model predictions against the actual clinical results. METHODS In this study, 349 head and neck cancer patients were included. For each patient the dose volume histograms (DVH) of parotids (separate and combined), mandible, submandibular glands (separate and combined) and salivary glands were calculated. The follow-up of those patients was recorded at different times after the completion of the treatment (7 weeks, 3, 7, 12, 18 and 24 months). Acute and late xerostomia and acute disgeusia were the clinical endpoints examined. A maximum likelihood fitting was performed to calculate the best estimates of the parameters used by the relative seriality model. The statistical methods of the error distribution, the receiver operating characteristic (ROC) curve, the Pearsons test and the Akaikes information criterion were utilized to assess the goodness-of-fit and the agreement between the pattern of the radiobiological predictions with that of the clinical records. RESULTS The estimated values of the radiobiological parameters of salivary glands are D50 = 25.2 Gy, γ = 0.52, s = 0.001. The statistical analysis confirmed the clinical validity of those parameters (area under the ROC curve = 0.65 and AIC = 38.3). CONCLUSION The analysis proved that the treatment outcome pattern of the patient material can be reproduced by the relative seriality model and the estimated radiobiological parameters. Salivary glands were found to have strong volume dependence (low relative seriality). Diminishing the biologically effective uniform dose to salivary glands below 30 Gy may significantly reduce the risk of complications to the patients irradiated for prostate cancer.

Laryngeal Organ Preservation Protocols: Are They Effective?

Objective: Understand the role of organ preservation protocol in locally advanced laryngeal carcinoma according to our experience and determine predictive factors. Method: The study selected all patients treated between 2004 and 2009. During the study period, all patients began treatment with induction chemotherapy (3 cycles of cisplatin and 5-fluoruracil in the majority of cases) followed by radiotherapy and concomitant or subsequent chemotherapy. The results were analyzed by clinical and image evaluation. Results: The study included 40 patients, with mean age of 55 years (range, 38 to 72 years), mainly men. Smoke and alcohol were present in more than 50%, and 70.7% had no comorbidities. Hypopharynx was the most common place (65.8%). At the end of induction chemotherapy 34.2% of patients had an answer >80%. The overall survival is 59% at 3 years. The relapse rate was of 24.7% with an average of time of 8 months (4 to 56 months). No statistical differences were found between different groups of TMN staging system. Conclusion: Different studies have shown that chemotherapy followed by radiotherapy is a valid alternative to surgery in locally advanced operable head and neck cancer, involving the larynx. Our study confirms these results. Local and cervical disease staging did not contribute as a predictive factor for survival or relapse.