Trans-oral brush proves useful for NPC detection in a local study
May 2014 , Jackey Suen
The obscured nature of the nasopharynx hinders early detection of nasopharyngeal carcinoma (NPC) with endoscopy, but this obstacle can be overcome with a comfortable and simple trans-oral “brush” device recently validated in a joint Hong Kong-Canadian study. [Otolaryngol Head Neck Surg 2014;150:602-609]
“Most of the patients acquire NPC in their most productive years [35-55 years old], which is of great concern,” said Professor William Wei of the University of Hong Kong (HKU), at a press conference. “Although early-stage NPC is highly curable with radiotherapy, it is not easily detectable with endoscopic examination. In addition, patients are reluctant to undergo endoscopy due to the associated discomfort and the rather asymptomatic nature of early NPC.”
Given the importance of early NPC detection, the HKU, Queen Elizabeth Hospital, Hong Kong, and the University of Toronto, Canada, jointly developed a new screening method by retrieving cells in the nasopharnyx (NP) and quantifying the presence of Epstein-Barr virus (EBV), which is known to be present in almost all NPC specimens. “This method consists of a trans-oral NP brush for cell collection, a dedicated solution for sample preservation, and a polymerase chain reaction [PCR] test for EBV quantification,” explained Dr. Raymond Ng of the University of Toronto.
The investigators conducted a study to validate the trans-oral NP brush method. Among 578 Chinese subjects from Hong Kong and Toronto, the presence or absence of NPC was first determined by the trans-oral NP brush method, and confirmed by biopsy and pathologic diagnosis. Notably, the trans-oral brush NP method showed an improvement in sensitivity (98.9 vs 94 percent), specificity (99.3 vs 97.1 percent), positive predictive value (96.9 vs 85 percent) and negative predictive value (99.7 vs 98.9 percent) compared with endoscopy. “It also provides an objective measurement of EBV DNA that indicates submucosal and early-stage cancers, which may not be visible on routine endoscopy,” noted Ng.
The NPC brush testing is currently available only in the private sector. Professor Dora Kwong of the HKU is now recruiting about 50 patients to assess the possibility of using the trans-oral brush biopsy for the detection of early local recurrence of NPC following radiotherapy. The results will be compared with existing biopsy methods and serum EBV DNA measurement.