Volumetric staging in oropharyngeal cancer patients treated with definitive IMRT.

BACKGROUND

The superiority of volumetric staging (VS) over TNM/TNM-grouping system was previously prospectively tested in our head neck cancer population treated with intensity-modulated radiotherapy (IMRT); gross tumor volume (GTV) was the strongest predictor for disease control. Aim of this work was to specifically assess the prognostic value of VS in oropharyngeal cancer (OC).

PATIENTS

Between 04/2002 and 12/2011, 277 consecutive OC patients underwent definitive IMRT. Mean/median follow-up was 33/27 months (3-113). Three volumetric cut-offs were used (resulting in 4 GTV subgroups: 1-15 cc (14%), 16-70 cc (62%), 71-130 cc (20%), >130 cc (4%)).

METHODS

Outcome in the OC subgroup was prospectively assessed with VS and compared with that resulting from TNM and AJCC staging.

RESULTS

Primary GTV was most reliably predicting local control (p<0.0001), all other outcome parameters were predicted best by the total GTV (p<0.0001).

CONCLUSION

This is -to our knowledge- the first volumetric staging system for OC, and was found to be most reliable in predicting outcome in OC patients treated with IMRT.