Individualized IMRT treatment approach for cervical lymph node metastases of unknown primary

The goal of the present study was to evaluate the outcome of risk-adapted planning treatment volumes (PTVs) in patients with cervical lymph node metastases of unknown primary cancer (UPC) treated with intensity-modulated radiotherapy (IMRT).

Between January 2006 and November 2012, 28 patients with cervical lymph node metastases of UPC were treated in our institution with IMRT either postoperatively (n = 20) or as definitive treatment (n = 8). Nodal involvement distributed as follows: N1 (n = 2), N2a (8), N2b (10), N2c (4), and N3 (4). Systemic therapy with cisplatin or cetuximab was added concomitantly in 20 of 28 patients (71 %). Radiotherapy using simultaneously integrated boost (SIB-IMRT) was carried out with 2.0 or 2.11 Gy single doses up to 66/70 Gy.

Mean/median follow-up was 31.6/30.5 months (range 3-78 months). In all, 15 of 28 patients were treated with unilateral SIB-IMRT (54 %). An elective PTV to the contralateral oropharynx and contralateral level II-III lymph nodes was carried out in 8 patients with PET-CT suspected but not histologically proven involvement, recurrences or former tumor of the oropharynx. More extended treatment fields were reserved for patients with N2c or bilaterally N3 status (n = 5). The 3-year overall survival, mucosal control, neck control and distant metastasis-free survival rates were 76, 100, 93, and 88 %, respectively. No patient suffered from a locoregional recurrence. Two patients treated with radiotherapy alone had persistent nodal disease. No grade II or higher late sequel has been observed.

Our single center approach to treat patients with cervical lymph node metastases of UPC with individualized, risk-adapted SIB-IMRT resulted in high locoregional tumor control and was well tolerated.