Natural course and tumor doubling time of nasopharyngeal carcinoma. A study of 15 patients.

Nasopharyngeal carcinoma (NPC) is a non-lymphomatous carcinoma that develops in the epithelial lining of the nasopharynx. The knowledge of natural course of tumor progression has been based on anatomical model without clinical correlation. This study is the first to describe and analyze the natural progression of NPC based on clinical information and calculate the tumor growth rate of NPC. Fifteen NPC patients who refused treatment after initial work-up and then subsequent re-presentation at a later time were recruited during the period from January 2003 to August 2009. Clinical data were analyzed and CT scans were used to calculate the tumor volumes. The time interval between the first planning CT image and the subsequent planning CT image was used to calculate the rate of tumor growth in this group of patients. The tumor volume doubling time can be calculated by using the formula DT=tln2/(lnV2-lnV1), where t is the time interval between measurements and V(2) and V(1) are the tumor volumes at the end and beginning of the time interval, respectively. Cranial nerves palsies such as diplopia and systemic upset were the most common reason for re-presentation and the consent for treatment. The median growth rate was 1.63mm(3) per day and the median tumor doubling time was 279days. This study is the first report in the literature looking at the natural progression of nasopharyngeal carcinoma (NPC) based on clinical information. The current study showed that NPC has a propensity to grow superiorly to involve the skull base rather than laterally or anteriorly. Although the tumor growth rate was very variable, the median natural NPC growth rate was 1.63mm(3)/day.