Effectiveness of radiotherapy with radical neck dissection in cancers of the head and neck. A retrospective analysis of 457 radical neck dissections performed over a 30-year period for cancers of the oral cavity, pharynx, and larynx was carried out. Two hundred thirteen patients underwent radiotherapy to the primary cancer site and/or to the neck. Of these, 164 underwent perioperative adjuvant radiotherapy and 24 underwent definitive radiation for cure and were followed up by salvage surgery. Thus, 188 patients received radiotherapy for nonrecurrent disease. Twenty-five additional patients underwent radiation for surgical failure following radical neck dissection. The goal of the study was to determine whether radiotherapy altered the course or end result of the disease. The T and N stage at onset of disease was similar for the radiotherapy and nonradiotherapy groups. Preoperative radiotherapy was effective in down staging the disease at the primary site and, to a lesser extent, in the lymph nodes, but had limited impact on survival. Failure to control the disease in the neck occurred in 60 (32%) of the 188 patients who received radiotherapy for primary disease; recurrence rates were lower in the combined therapy group than in the surgical group of patients with N2 and N3 stages of disease. The 3-year disease-free survival was 45%; this was no better than the 63% survival rate in patients who did not receive radiotherapy, although survival was better in the combined therapy group for patients with N3 stage of disease. The worst results were in those patients who were irradiated for surgical failure (14% survival); the 24 patients who required salvage radical neck dissection following failure of definitive radiotherapy for cure had a 42% survival. 