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

Abstract

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.Electronic supplementary materialThe online version of this article (doi:10.1186/s13014-015-0345-4) contains supplementary material, which is available to authorized users.

Analysis of CT-verified loco-regional recurrences after definitive IMRT for HNSCC using site of origin estimation methods

“…The number of CT-verified T-and N-site loco-regional recurrences inside high-dose treatment volume was lower than observed in other studies [4,10,19]. The GTV-CTV1 margin in the present study was 0 mm in 80% of cases, whereas other centers use up to 10 mm margins around GTV or even the entire region harboring the tumor [10][11][12]. If we had included the first 10 mm outside the CTV1 margin, 58% of all loco-regional recurrences would be included in CTV1 þ 10 mm instead of 40%.…”

“…A less time-dependent approach for characterizing a loco-regional failure is to define a possible point of recurrence origin. Assuming that tumor growths isotropically around the point of initial failure, the center of mass (COM) of the recurrence volume can be used to identify the initial recurrence point [10][11]. Nevertheless, recurrences often appear in irregular shapes, which make the COM method less obvious as representative for the initial recurrence point.…”

Treatment failure prediction for head-and-neck cancer radiation therapy

“…All patients included in this study were treated with curative IMRT either alone (non-concomitant) or in combination with concomitant chemotherapy (cisplatin or cetuximab) [16].…”

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

“…7 Patients were divided into two groups depending on whether the value of the mean dose converted to a 2 Gy fractionation in the primary tumour was inferior or superior to 70.2 Gy (Group ,70 and Group $70, respectively). The reasons for selecting the dose delivered to the primary tumour were threefold: first, recurrences occurred mostly in the vicinity of the primary tumour; 8 second, the biological dose escalation, through an increase in dose per fraction, was mostly applied to this volume; and third, reducing OTT resulted in clinical benefits in controlling the gross tumour but had little effect on the control of neck nodes. 2,9 A dose-response effect, resulting from the biological dose escalation obtained by an increase in dose per fraction and reducing OTT, would thus be more evident in the primary tumour.…”

“…6,8 In summary, target volume delineation followed Gregoire et al 10 Prescription dose to primary tumour volume and large adenopathies was around 70.2 Gy and to high-and low-risk lymph nodes, it ranged from 50.4 to 59.4 Gy. The main organs at risk included in plan optimization were: spinal cord, brainstem, mandible, parotid glands, thyroid and others considered relevant for each pathology.…”