Intensity-modulated radiotherapy for cervical lymph node metastases from unknown primary cancer.

Purpose: To compare the effectiveness of intensity-modulated radiotherapy (IMRT) and conventional (two-dimensional) radiotherapy in the treatment of cervical lymph node metastases from unknown primary cancer (UPC).

Methods And Materials: Between February 2003 and September 2006, 23 patients with UPC of squamous cell carcinoma were treated with IMRT. Extended putative mucosal and bilateral nodal sites were irradiated to a median dose of 66 Gy. In 19 patients, IMRT was performed after lymph node dissection, and in 4 patients primary radiotherapy was given. The conventional radiotherapy group (historical control group) comprised 18 patients treated to a median dose of 66 Gy between August 1994 and October 2003.

Results: Twenty patients completed treatment. As compared with conventional radiotherapy, the incidence of Grade 3 acute dysphagia was significantly lower in the IMRT group (4.5% vs. 50%, p = 0.003). By 6 months, Grade 3 xerostomia was detected in 11.8% patients in the IMRT group vs. 53.4% in the historical control group (p = 0.03). No Grade 3 dysphagia or skin fibrosis was observed after IMRT but these were noted after conventional radiotherapy (26.7%, p = 0.01) and 26.7%, p = 0.03) respectively). With median follow-up of living patients of 17 months, there was no emergence of primary cancer. One patient had persistent nodal disease and another had nodal relapse at 5 months. Distant metastases were detected in 4 patients. The 2-year overall survival and distant disease-free probability after IMRT did not differ significantly from those for conventional radiotherapy (74.8% vs. 61.1% and 76.3% vs. 68.4%, respectively).

Conclusions: Use of IMRT for UPC resulted in lower toxicity than conventional radiotherapy, and was similar in efficacy.