Histosurgical mapping of endoscopic endonasal surgery of sinonasal tumours to improve radiotherapy guidance

PURPOSE

Endoscopic endonasal surgery (EES) is becoming a standard for most malignant sinonasal tumours. Margin analysis after piecemeal resection is complex and optimally relies on accurate histosurgical mapping. Postoperative radiotherapy may be adapted based on margin assessment mapping to reduce the dose to some sinonasal subvolumes. We assessed the use of histosurgical mapping by radiation oncologists (RO).

MATERIAL AND METHODS

A French practice survey was performed across 29 ENT expert RO (2 did not answer) regarding integration of information on EES, as well as quality of operative and pathology reportsto refine radiotherapy planning after EES. This was assessed through an electronic questionnaire.

RESULTS

EES was ubiquitously performed in France. Operative and pathology reports yielded accurate description of EES samples according to 66.7% of interviewed RO. Accuracy of margin assessment was however insufficient according to more than 40.0% of RO. Additional margins/biopsies of the operative bed were available in 55.2% (16/29) of the centres. In the absence of additional margins, quality of resection after EES was considered as microscopically incomplete in 48.3% or dubious in 48.3% of RO. As performed, histosurgical mapping allowed radiotherapy dose and volumes adaptation according to 26.3% of RO only.

CONCLUSIONS

Standardized histosurgical mapping with margin and additional margin analysis could be more systematic. Advantages of accurate EES reporting could be dose painting radiotherapy to further decrease morbidity in sinonasal tumours.

Recommendations for postoperative radiotherapy in head & neck squamous cell carcinoma in the presence of flaps: A GORTEC internationally-reviewed HNCIG-endorsed consensus

INTRODUCTION

Head and neck reconstructive surgery using a flap is increasingly common. Best practices and outcomes for postoperative radiotherapy (poRT) with flaps have not been specified. We aimed to provide consensus recommendations to assist clinical decision-making highlighting areas of uncertainty in the presence of flaps.

MATERIAL AND METHODS

Radiation, medical, and surgical oncologists were assembled from GORTEC and internationally with the Head and Neck Cancer International Group (HNCIG). The consensus-building approach covered 59 topics across four domains: (1) identification of postoperative tissue changes on imaging for flap delineation, (2) understanding of tumor relapse risks and target volume definitions, (3) functional radiation-induced deterioration, (4) feasibility of flap avoidance.

RESULTS

Across the 4 domains, international consensus (median score ≥ 7/9) was achieved only for functional deterioration (73.3%); other consensus rates were 55.6% for poRT avoidance of flap structures, 41.2% for flap definition and 11.1% for tumor spread patterns. Radiation-induced flap fibrosis or atrophy and their functional impact was well recognized while flap necrosis was not, suggesting dose-volume adaptation for the former. Flap avoidance was recommended to minimize bone flap osteoradionecrosis but not soft-tissue toxicity. The need for identification (CT planning, fiducials, accurate operative report) and targeting of the junction area at risk between native tissues and flap was well recognized. Experts variably considered flaps as prone to tumor dissemination or not. Discrepancies in rating of 11 items among international reviewing participants are shown.

CONCLUSION

International GORTEC and HNCIG-endorsed recommendations were generated for the management of flaps in head and neck radiotherapy. Considerable knowledge gaps hinder further consensus, in particular with respect to tumor spread patterns.

Patterns of Failure in Patients With Head and Neck Squamous Cell Carcinomas of Unknown Primary Treated With Chemoradiotherapy

Background:

To evaluate the patterns of failure in patients treated for head and neck carcinoma of unknown primary and to discuss treatment practices concerning radiotherapy target volumes definition and dose prescription.

Methods:

Eleven patients presenting a locoregional recurrence after head and neck carcinoma of unknown primary treatment with curative-intent radiochemotherapy performed between 2007 and 2017 in the departments of radiation oncology of 2 French cancer institutes. Images of the computed tomography scan or the magnetic resonance imaging performed at the time of the recurrence were fused with those of the simulation computed tomography scan to delimit a volume corresponding to the recurrence and to define the area of relapse compared to the volumes treated.

Results:

Irradiation was unilateral in 6 cases and bilateral in 5 cases. The median time to onset of recurrence was 7.24 months (extreme 3-67.7 months). Six patients had only a neck node recurrence, 3 had a neck node and subsequent primary recurrence, and 1 had only a median subsequent primary recurrence. Only 1 patient had synchronous distance progression to local recurrence. All neck node recurrences were solitary and ipsilateral. The subsequent primary recurrences were in the oropharynx in 3 cases and in the contralateral oral cavity in one case. All neck node recurrences were into the irradiated volume. The subsequent primary recurrences were either within or in border of the irradiated volumes. The median of the mean dose, received by neck node recurrences, was 69.9 Gy and that of the mean dose, minimum dose, maximum dose, and dose received by 95% of the volume of recurrence was 66.7 Gy. For the primary relapses, the median of the mean dose was 52.1 Gy and that of the mean dose, minimum dose, maximum dose, and dose received by 95% of the volume of recurrence was 39.9 Gy.

Conclusions:

All local nodal recurrences occurred at sites that received high radiotherapy doses and doses received by sites of eventual failure did not vary significantly from sites that remain in control.

P14.78 Hypofractionated stereotactic radiotherapy as a salvage therapy for recurrent high-grade gliomas: Single-center experience

BACKGROUND

The standard of care for patients with recurrent glioblastoma or grade III glioma has not yet been clearly defined and many approaches are available for salvage strategies. These include surgery, re-irradiation or systemic agents. For the treatment of High-Grade (HGG) recurrence by radiation therapy, Hypofractionated Stereotactic Radiotherapy (HFSRT) is an interesting approach because it is minimally invasive, ambulatory, short-lasting and well tolerated. The aim of this study was to evaluate the efficacy of and safety to HFSRT as alvage treatment for patients suffering from HGG relapse in our cancer center and to compare these results with the literature.

MATERIAL AND METHODS

Between March 2012 and March 2017, 32 consecutive patients (12 women, 20 men) treated in a single-center were retrospectively included included in this study.Grade III gliomas were diagnosed in 14 patients and grade IV in 18 patients. Thirty-four lesions were treated with HFSRT on LINAC. HFSRT delivered a dose of 30 Gy in six fractions of 5Gy (27 Gy in three fractions for one patient) with two or three fractions per week. The treatment plans were normalized to 100% at the isocenter, and prescribed to the 80 % isodose line. Clinical outcomes and prognostic factors were analyzed.

RESULTS

HFSRT characteristics: The median tumor volume was of 6.1 (0.1–42.2) cm3 and the median PTV was 15 (0.6–67.5) cm3. The median maximum dose, median minimum dose and median mean dose were 38.7 (32.7–42.0) Gy, 29.1 (14.0–32.4) Gy and 35.1 (31.5–37.5) Gy, respectively. Median follow-up was 20.9 months.

Median overall survival (OS) following HFSRT was 15.6 months (Median OS for patients patients with GBM and grade III glioma were 8.2 and 19.5 months, respectively; p=0.0496).

Progression-free survival (PFS) was 3.7 months (Median PFS for patients with GBM and grade III glioma were 3.6 and 4.5months, respectively; p=0.2424).

In multivariate analysis, tumor grade III (p=0.0027), an ECOG status <2 at the time of reirradiation (p=0.0023) and a mean dose >35 Gy (p=0.0055) significantly improved OS. A maximum reirradiation dose above 38 Gy (p=0.0179) was significantly associated with longer PFS.

Treatment was well tolerated, no acute toxicity > grade 2 was observed.

During the follow-up, ten patients (31.25%) had suspected radionecrosis. In six patients, this suspicion corresponded to tumor progression. For the other patients, radionecrosis was suggested on multi-modal MRI.

CONCLUSION

HFSRT appears to be a feasible and effective salvage treatment option for recurrent high-grade gliomas, with OS of 15.6 months. Prognostic factors associated with longer OS were a good general state of health and grade III glioma. Dosimetric data suggested that the dose gradient had an impact on tumor control and indicate that a study with dose-escalation is warranted. These results need to be confirmed in a prospective study with a greater number of patients.

Patterns of locoregional relapses for patients with esophageal cancer for whom exclusive chemoradiotherapy failed: A plea for dose escalation and elective nodal irradiation

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Background: Nearly half of the patients (pts) with an esophageal cancer (EC) have a locoregional failure (LRF) after exclusive chemoradiation (eCRT). eCRT delivering 50Gy remains the standard of care for non operable pts. We aim to evaluate the patterns of LRF with respect to planned dose and/or the incidental (unplanned) dose that covered LRF. Methods: Twenty-two pts with EC who failed locally and/or regionally in their follow-up were exclusively reviewed. All the pts have been initially treated (t0) in a curative intent with eCRT. Co-image registration of CT or PET-CT at time of failure and planning CT at t0 was used for image fusion. Each nodal failure (Nf) and each local failure of the primary tumor (Lf) has been outlined, as well as each nodal station (NS) including Nf according to the RTOG classification. Dosimetric parameters in relation with Lf, Nf and involved NS were derived from the initial dosimetric plan. Results: All the patients underwent eCRT including a 5-FU based chemotherapy regimen. Eighteen patients were treated with elective nodal irradiation (ENI) whereas 4 pts did not. The median dose delivered was 50Gy [50Gy-64Gy]. In the follow-up period, 14 pts were in complete response, 3 pts in partial response, 4 pts had a progressive disease (1pt unknown). The median delay between the start of radiotherapy and LRF was 14.3 months [4.27-48.46]. 13 pts had a Lf (included in “planned-dose”), 9 pts had a Nf, 2 pts had a Lf with Nf and 7 pts had a concomittant distant failure. Among pts with Nf, 8 failures were in-field whereas 3 pts had an out-field relapse. Re-calculated doses for NS delineated on the CT performed at t0 were significantly less important than the planned dose (see Table). Conclusions: Our results suggest that an inadequate dose to both the primary tumor and NS could explain high LRF rates observed in EC. A French randomized phase III trial (NCT 01348217) is currently testing a higher dose to the primary tumor and/or ENI with IMRT in an attempt to improve locoregional control. [Table: see text]