Tumor regression patterns by follow-up duration in patients with nasopharyngeal carcinoma treated with concurrent chemoradiotherapy.

The aim of this study was to describe the patterns of tumor regression with respect to follow-up duration after chemoradiotherapy in patients with nasopharyngeal carcinoma. A total of 27 patients with nasopharyngeal carcinoma were included and received definitive concurrent chemoradiotherapy. Patterns of primary tumor regression and development of locoregional recurrences were evaluated by imaging studies every 1 to 2 months. Primary tumors gradually regressed over the period of follow-up. The median time to full regression was 4.9 months (range, 1.5-19.4). In 61.5% of patients, the primary tumor continued to regress for >4 months after completion of chemoradiotherapy. Six patients experienced locoregional recurrence during follow-up, all of which occurred after full regression of the primary tumor. A patient group with delayed regression did not have poorer prognosis than a patient group with early regression. Older age, non-current-smoker status, advanced T stage, and higher daily radiation dose were significantly associated with delayed primary tumor regression. Nasopharyngeal carcinoma continued to regress for >4 months after chemoradiotherapy in a considerable number of patients. We recommend waiting for >4 months for full regression of nasopharyngeal carcinomas after chemoradiotherapy, if signs of persistent or recurrent disease are not evident on follow-up examination.