The management of patients with cervical lymph node metastases from unknown primary tumours is a major challenge in oncology. This study presents data collected from all five oncology centres in Denmark.

Of the 352 consecutive patients with squamous cell or undifferentiated tumours seen from 1975 to 1995, a total of 277 (79%) were treated with radical intent. The general treatment policy at all centres during the entire study period has been to treat all suitable candidates with radiotherapy to both sides of the neck and include elective irradiation of the mucosal sites in nasopharynx, and larynx, hypopharynx and larynx (81%). Irradiation of the ipsilateral neck only was done in 26 patients (10%). Radical surgery was the only treatment in 23 N1-N2 patients (9%).

The 5-year estimates of neck control, disease-specific survival and overall survival for radically treated patients were 51, 48 and 36%, respectively. The emergence of the occult primary was observed in 66 patients (19%). About half of the emerging primaries were within the head and neck region with oropharynx, hypopharynx and oral cavity being the most common sites. Emerging primaries outside the head and neck region were primarily located in the lung (19 patients) and oesophagus (five patients). The frequency of emerging primary in the head and neck was significantly higher in patients treated with surgery alone, the actuarial risks at 5-year being 54+/-1% (no RT) vs. 15+/-3% (with RT), P<0.0001. The most important factor for neck control was nodal stage (5-year estimates 69% (N1), 58% (N2) and 30% (N3)). Other important parameters for neck control and disease-specific survival included haemoglobin, gender and overall treatment time. Patients treated with ipsilateral radiotherapy had a relative risk of recurrence in the head and neck region of 1.9 compared with patients treated to both neck and mucosa. At 5 years, the estimated control rates were 27% (ipsilateral) and 51% (bilateral; P=0.05). The 5-year disease-specific survival estimates were 28 and 45%, respectively (P=0.10).

This study has confirmed that patients with neck node metastases from occult head and neck cancer have clinical features and prognosis similar to other head and neck malignancies. Extensive irradiation to both sides of the neck and the mucosa in the entire pharyngeal axis and larynx resulted in significantly less loco-regional failures compared with patients treated with ipsilateral techniques, but only a trend towards better survival. A prospective randomized trial is required to determine the optimal strategy in terms of locoregional control, survival and morbidity.