Patterns of recurrence in electively irradiated lymph node regions after definitive accelerated intensity-modulated radiotherapy for head and neck squamous cell carcinoma
Menée sur 264 patients atteints d'un carcinome épidermoïde de l'oropharynx, du larynx ou de l'hypopharynx de stade cT2-4N0-2M0 et traités par radiothérapie accélérée avec modulation d'intensité entre 2008 et 2012, cette étude évalue le taux actuariel de récidive à deux ans au niveau des régions ganglionnaires irradiées, puis identifie les formes de récidive
Purpose/Objective(s) : To provide a comprehensive risk-assessment on the patterns of recurrence in electively irradiated lymph node regions after definitive radiotherapy for head and neck cancer. Methods and Materials : Two-hundred-and-sixty-four patients with stage cT2-4N0-2M0 squamous cell carcinoma of the oropharynx, larynx or hypopharynx treated with accelerated IMRT between 2008-2012 were included. On the radiotherapy planning CT-scans from all patients, 1166 lymph nodes (short-axis diameter ≥5mm) localized in the elective volume were identified and delineated. The exact sites of regional recurrences were reconstructed and projected on the initial radiotherapy planning CT-scan by performing co-registration with diagnostic imaging of the recurrence. Results : The actuarial rate of recurrence in electively irradiated lymph node regions at 2 years was 5.1%(95% CI:2.4-7.8%). Volumetric analysis showed an increased risk of recurrence with increasing nodal volume. ROC analysis demonstrated that the summed long- and short-axis diameter is a good alternative for laborious volume calculations, using ≥17mm as cut-off (hazard ratio: 17.8; 95%CI: 5.7-55.1; p<0.001). Conclusions : An important risk-factor was identified that can help clinicians in the pre-treatment risk-assessment of borderline-sized lymph nodes. Not overtly pathologic nodes with a summed diameter ≥17mm may require a higher than elective RT dose. For low-risk elective regions(all nodes <17mm), the safety of dose de-escalation below the traditional 45-50Gy should be investigated
http://www.redjournal.org/article/S0360-3016%2815%2926809-5/abstract