Local recurrences after curative IMRT for HNSCC: Effect of different GTV to high-dose CTV margins.
INTRODUCTION
The aim was to analyze position of CT-verified local recurrences (LR) and local control (LC) among three centers that used different GTV to CTV1 margins.


MATERIALS AND METHODS
In total, 1576 patients completing radical primary IMRT for larynx, pharynx, oral cavity HNSCC in three centers in Denmark between 2006 and 2012 were included. CT-verified LRs were analyzed as possible points of recurrence origin and compared between groups of small (0-2.5 mm), larger (>2.5 mm), and anatomical GTV-CTV1 margins. The recurrence point's position relative to the GTV and 95% prescription dose was evaluated. Overall local control rate was evaluated using Cox uni- and multi-variate analysis.


RESULTS
After a median follow-up of 41 months, 272 patients had local failure. Median GTV-CTV1 margin in Center1, 2 and 3 was 0.0, 3.7 and 9.7 mm, respectively. 51% of local recurrences were inside the GTV. No difference in distribution of LRs in relation to GTV surface (p = 0.4) or the dose to LRs (p = 0.2) was detected between the groups. A difference in LC was found univariate between the centers (p = 0.03), but not in multivariate analysis (p = 0.4).


CONCLUSIONS
No relation was found between the recurrences' distributions as function of the margins used at three centers. In multivariate analysis, local control was not influenced by the centers.
['Zukauskaite|Ruta|R|', 'Hansen|Christian R|CR|', 'Grau|Cai|C|', 'Samsøe|Eva|E|', 'Johansen|Jørgen|J|', 'Petersen|Jørgen B B|JBB|', 'Andersen|Elo|E|', 'Brink|Carsten|C|', 'Overgaard|Jens|J|', 'Eriksen|Jesper G|JG|']
D002294:Carcinoma, Squamous Cell D004307:Dose-Response Relationship, Radiation D005260:Female D006258:Head and Neck Neoplasms D006801:Humans D008297:Male D009364:Neoplasm Recurrence, Local D009367:Neoplasm Staging D011879:Radiotherapy Dosage D011880:Radiotherapy Planning, Computer-Assisted D050397:Radiotherapy, Intensity-Modulated D000077195:Squamous Cell Carcinoma of Head and Neck
Local recurrence IMRT HNSCC Margins Local control GTV to CTV margins