Pretreatment PET and post-treatment pathologic nodal status as a predictor for distant metastasis in locally advanced head and neck squamous cell carcinoma treated with definitive concurrent chemoradiotherapy.

Abstract

5541 Background: Advances in concurrent chemoradiation (CCRT) and neck dissection (ND) have yielded excellent LR control in node+ve head and neck squamous cell cancer (SCC). Distance metastasis (DM) is a major pattern of failure and obstacle to cure. High metabolic tumor volumes derived from pre-treatment PET and persistent pathologic neck disease after CCRT have been associated with worse outcomes. Methods: From 1/99-12/08, 106 pts with node+ve SCC were treated with CCRT using platinum based chemotherapy. Tumor sites consisted of: oropharynx (87), larynx (11), unknown primary (4), hypopharynx (2) and oral cavity (2). 117 planned ND were performed 6-8 weeks after CCRT. Median age: 56. Males: 70% N1 (6) 6%, N2a (6) 6%, N2b (46) 45%, N2c (39) 38%, and N3 (20) 20%. 46 pts (45%) underwent pretreatment PET and the metabolic nodal volume (MNV) was calculated by the product of the mean standard uptake value and the nodal volume. Results: Residual nodal disease (pN+) was found in 29% of ND; N1-2a 17%, N2b 28%, N2c 31% and N3 45%. At a median followup of 35 months (3-128 ms), the main pattern of failure in pN+ compared to pN- was DM (3yr: 33% vs 12%, p=0.01, respectively). 3yr LR failure was also increased in pN+ vs pN- (18% vs 3%-, p=0.07, respectively). The 3yr incidence of DM according to N-stage was as follows: N1-2a:0, N2b12%, N2c 28%, N3, 35%. Patients with high volume ipsilateral neck disease had a higher incidence of DM if pN+ vs pN- as follows: N2b: (3yr DM 32% vs 4%, p=0.02) and N3 (60% vs 14%, p=0.07), respectively. For the subgroup of 46 pts staged with PET/CT, the median value for MNV was 71. Pts with high MNV values (>71) were at lower risk for having pN+ [17% (4/24) vs. 43% (10/23), p=0.045] but higher risk for DM (2yr: 32% vs 15%, p=0.09) compared to those with low MNV values (<71). In pts with high MNV, the 3yr DM was higher in pLN+ vs pLN- (67% vs 25%, p=0.05, respectively) as it was in low MNV pts (3yr DM 30% vs 0%, p=0.12). Conclusions: Pathologic residual nodal disease after definitive CCRT and high pretreatment MNV predicts a greater risk for DM. N2b-3 pts with high MNV and pN+ after CCRT+ND warrant consideration for additional adjuvant therapy.