Radiotherapy of Metastatic Neck Nodes from an Unknown Primary Site

Park, In Kyu; Yun, Sang Mo; Kim, Jae Cheol

Abstract

PURPOSE: This study was to evaluate survival, failure patterns, and prognostic factors of patients with metastatic neck nodes from an unknown primary site.
MATERIALS AND METHODS
A retrospective analysis was done for 35 patients with metastatic neck nodes from an unknown primary site who were treated with radiation from January 1986 to September 1994. There were 26 male and 9 female patients. Patients' age ranged from 41 to 74 years (median 58 years). Stage distribution showed 1 patient with N1, 27 with N2, and 7 with N3. Amomg these patients, 7 with a supraclavicular lymph node alone were included. The histologic type was squamous cell carcinoma in 22 patients, undifferentiated carcinoma in 6, adenocarcinoma in 4. We could not classify a histologic type in 3 patients. Radiation therapy alone was done in 7 patients, induction chemotherapy and radiation therapy in 10, and postoperative radiation therapy in 18. Radiation therapy fields included both neck and pharyngeal axis, and total dose was 40-95.6Gy (median 60Gy) using 6MV X-ray. Chemotherapy consisted of 2 cycles of 5-fluorouracil and cisplatin. Surgical methods were a radical neck dissection in 17 patients and an excisional biopsy in 1 patient. Follow-up time ranged from 2 to 95 months, median 15 months.
RESULTS
Overall and disease-free survival rate at 4 years were 33.4% and 33.9%, respectively. The factors associated with the overall survival rate were histologic type(adenocarcinoma vs. non-adenocarcinoma, p=0.0005), N stage(p=0.023), and the site of involved nodes(p=0.021). According to the treatment modality, 2-year survival rate was 14.3% in radiation therapy alone group, 35.8% in induction chemotherapy and radiation thrapy, and 37.5% in postoperative radiation therapy(Fig. 4, p=0.05), which might be due to the difference of N stage distribution. The failure patterns were analyzed in 25 patients with a complete response to the treatment. Local failure wasnoted in 7 patients, distant metastases in 6, local failure and distantmetastases in 1. Excluding the 7 patients with supraclavicular lymph node metastaes alone, 28%(7/25) of the patients had distant metastases. During the follow-up period, 11%(3/35) of the patients showed a delayed primary site, 1 in oral cavity, 1 in nasopharynx, and 1 in hypopharynx.
CONCLUSION
N stage, the site of involved node, and histologic type were associated with survival rate. In patients with advanced N stage, curative rather than inductive chemotherapy is needed because combined surgery and radiation therapy achieved poor results and considerable patients developed distant metastases.