Long-term results of radio(chemo)therapy in metastatic carcinoma to cervical lymph nodes from an unknown primary. Adult Comorbidity Evaluation 27 score as a predictor of survival

Purpose To evaluate the effectiveness and toxicity of curative (chemo)radiotherapy in patients with metastatic carcinoma to cervical lymph nodes from an unknown primary. Methods Retrospective study of 90 consecutive patients, treated with curative radiotherapy from 2003 to 2018 (median age 59 years; current/former smokers 76%) was conducted. The distribution of nodal staging was as follows: N1: 12%, N2a: 21%, N2b: 43%, N2c: 10%, N3: 13%. In 62% of patients, neck dissection was performed before radiotherapy. Concomitant chemotherapy was given to 64% of patients. Results The median follow-up of surviving patients was 86 months. The median total radiotherapy dose achieved was 70 Gy. The 5‑ and 10-year locoregional control were 84% in both cases, while 5‑ and 10-year distant control were 90% and 89%, respectively. A primary tumor in the head and neck area was detected in only 2 patients. No patient had an initial failure in the pharyngeal axis or contralateral cervical nodes. The 5‑ and 10-year overall survival were 55% and 42%, respectively. Severe early toxicity occurred in 71%; severe late toxicity in 33% of patients. Multivariate analysis demonstrated N‑status (hazard ratio [HR] 2.424; 95% confidence interval [CI] 1.121–5.241; p = 0.024) and comorbidity scores assessed by ACE-27 (Adult Comorbidity Evaluation; HR 3.058; 95% CI 1.489–6.281; p = 0.002) as two independent prognostic factors for overall survival. Conclusion The results of our work study demonstrate the high effectiveness of curative (chemo)radiotherapy on the pharyngeal axis and bilateral cervical nodes with long-term locoregional and distant control in 3/4 of the treated patients. N‑status and comorbidity scores were shown as strong prognostic factors influencing overall survival.