Trends in the clinical management of nasopharyngeal carcinoma

Abstract

Nasopharyngeal carcinoma (NPC) is well known as one of the major cancers seen in radiotherapy departments throughout mainland China. Although the areas of highest incidence remain in the southern regions of our country, it has been noted that there has gradually been an increased frequency northwards. It has, therefore, become increasingly important that on the basis of past experiences, results in the treatment of NPC be further improved. As shown by Lee et al., the most important single factor has been the extent of the primary lesion at first treatment. This has been repeatedly emphasized by all papers on the treatment of NPC (3, 6, 10, 14). Unfortunately, the proportion of early cases (if defined as the primary tumor being limited to the NP cavity with no cervical node metastasis) has remained small, always rarely more than 15% of the total cases seen (1, 2, 3). It has been rather discouraging to find that throughout the past years, although the techniques of radiation therapy have been greatly improved, the proportion of such cases have not improved to any marked degree. Clinical symptoms are usually indicative of more extensive primary lesions, and the appearance of neck node enlargement immediately makes the prognosis poorer. It is now well known that Epstein-Barr virus is serologically associated with NPC, and the presence of antibody to EBV has led to various methods of titration to assay the status of the NPC patient. Li (8) has reported that in a screening of 3,960 persons by IgA/VCA titration, only 0.5% had a positive reaction of l:lO, but in 1,006 NPC patients, it was positive in 90.9%. Although mass screening of large populations would not be feasible, it is possible that such procedures could be of value in high risk populations. For the present, the fact remains that in nearly all reports (3, 6, 15), Stage III-IV cases predominate, comprising 70-75% of the total. It is a regretable fact that most of the N2-N3 cases presenting for treatment were initially seen by doctors when the cervical nodes were in Nl, but misdiagnosis and inadequate treatment often delayed the cases into the late stages of disease. We can only hope that wide-spread reeducation in NPC of our general practitioners would help to reverse the present ratio of early to late cases. Presentation of results in the radiation treatment of NPC is important in the sharing of experiences in order to improve clinical management. However, this needs, above all, a common basis (the most important of which is clinical staging) because overall control or survival rates cannot define the individual situation. As with other cancers, in NPC, the TNM method of staging is used, and the actual definitions of the components T and N differ quite widely. The majority of institutions in mainland China have adopted the Changsha criteria after the national symposium on NPC held in 1979. Hong Kong follows Professor J. H. C. Ho’s methods (5), while most other countries use the UICC or AJCC classification. These disparities make it difficult to share experiences on how to manage different stages of NPC; nevertheless, because there are too many other factors involved, the author believes that it is not truly possible to compare retrospective results even if the same methods of clinical staging are used. This may be possible only when prospective randomized studies are done under strict, regimented protocols. Also, the method of statistical analysis will have to be unified because, as Hwang has pointed out (7), many authors present the results of patients treated by radiotherapy or the results of those that have received adequate doses, while others may include all cases seen. A survey of 572 cases diagnosed as T 1 -T2NO was taken from 5377 cases; these cases were gathered from 12 large hospitals in China (9). Although the Changsha method followed the UICC criteria for Tl and T2, this survey showed that Professor Ho’s concept of Tl defining the primary tumor as being confined to the nasopharynx is more prognostically significant than the Changsha Tl and T2. However, in light of the importance of CT scans of the