Issues in the management of nasopharyngeal carcinoma
Introduction
Nasopharyngeal carcinoma, commonly abbreviated to NPC, has already been noted by many authors to be a malignant disease particular to southern Chinese, with a yearly incidence of between 20 and 25/105 [1], and a male to female ratio of usually 3:1. A survey from Guangzhou has reported an incidence as high as 46/105 [2]. In marked contrast, the incidence in non-Chinese populations are very low: in Australia it is only 0.80/105, in Japan 0.06, and in the United States and the UK 0.05 [3]
Since the majority of overseas Chinese are descended from southern Chinese ancestors, it is not surprising that there is also a high frequency in Southeast Asia. Thus, the greatest number of papers on NPC have come from China and Singapore.
Histopathologically, the World Health Organization (WHO) introduced an NPC classification based on the degree of differentiation: WHO type 1: squamous cell carcinoma which account for one third to one half in low risk populations, but less than 5% in endemic regions; WHO type 2: nonkeratinizing epidermoid carcinoma; WHO type 3: undifferentiated carcinoma [4]. In the Chinese patients, over 95% are WHO type 3, the rest are mostly type 2, and rarely type 1. This may in part explain the differences in treatment results reported for Chinese and non-Chinese patients
Due to the language barrier the majority of articles published in mainland China reporting experiences of treating thousands of NPC cases per year have not be available to radiotherapists abroad. This paper discusses present issues in the management of NPC on the basis of data published in English, as well as those published in Chinese in mainland China.
Numerous papers have dealt with various aspects of basic research, diagnosis and treatment. However, up to date, opinions still differ on several issues, some of which were brought up at the UICC Workshop on Nasopharyngeal Cancer in Singapore in February of 1998. Although some questions were answered, still more remained controversial, and will be the main topics of discussion in this paper.
Section snippets
Clinical diagnosis—role of the physician
In all reports on the clinical results of radiation treatment of NPC, an undisputed prognostic factor that affects survival rates is the clinical stage of disease at presentation for treatment. All authors have reported that the best results are always for early cases, i.e. treated in Stages I and II, (Table 1) with 5-year survival rates of approximately 90 and 70%, respectively [5], [6], [7]. However, in all these reports, whichever method of clinical staging used, the proportion of Stage I,
Treatment
The treatment of choice of nasopharyngeal carcinoma has always been radiotherapy, but in recent years the combination with chemotherapy has been the subject of intensive research in an effort to improve results, especially in the more advanced cases in whom radiotherapy alone has not been found to be capable of controlling the lesions, such as bulky cervical node metastases and in patients suspected of having occult distant metastases. However, many radiotherapists are not convinced that
Radiotherapy—when and how
Despite the fact that the results of treatment of NPC are among the best of the cancers treated by definitive radiotherapy, aside from distant metastases as the main cause of failure, there still remains 20-30% of the cases that recur loco-regionally [86]. However, NPC is one of the few cancers that has been re-treated successfully by radiotherapy for loco-regional recurrence [87].
Personal experience has shown that in post-radiation cases recurrent in the nasopharynx, simply repeating a routine
Complications of radiation treatment
In the past, not much attention was given to late complications of normal tissues surrounding the nasopharyngeal area after radical doses to the primary lesion. Actually, in NPC many kinds of normal tissues surround the nasopharyngeal cavity: the spinal cord, brain stem, temporal lobes, hypothalamus, pituitary gland, optic nerves and optic chiasma, lens, middle ear canals, etc. In recent years however, due to improvements in survival rate and the advent of CT and MRI examinations, late
Conclusion
Nasopharyngeal carcinoma is one of the most frequently seen cancers of the head and neck in southern China and many other countries in Southeast Asia. An enormous amount of work has been done by many well known experts in these regions, yet there are many problems that still need to be solved, concepts to be clarified, and radiation techniques to be standardized. Only then will the efforts of all those treating nasopharyngeal carcinoma be able to be pooled and conclusive solutions to many of
Reviewers
This paper was reviewed by Prof. Karen Fu, MD, Department of Radiation Oncology, University of California, Box 0226, San Francisco, CA 94143-0226, USA; Prof. K. Kian Ang, MD, Department of Radiation Oncology, U.T.M.D. Anderson Cancer Centre, 1515 Holcombe Blvd, Box 97, Houston, TX 77030, USA; and Prof. François Eschwege, MD, Department of Radiotherapy, Institut Gustave Roussy, 39 Rue Camille Desmoulins, 94805 Villejuif Cédex, France.
Prof. Taifu Liu received his M.D. from the Aurora University in Shangai in 1949. Since then he has worked as a radiotherapist at the Cancer Hospital of the Shangai Medical University. He was head of the Department of Radiation Oncology at this hospital until 1989. He was made an Honorary Fellow of the American College of Radiology in 1988. His main interests are in the radiotherapy of Head and Neck cancer.
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Prof. Taifu Liu received his M.D. from the Aurora University in Shangai in 1949. Since then he has worked as a radiotherapist at the Cancer Hospital of the Shangai Medical University. He was head of the Department of Radiation Oncology at this hospital until 1989. He was made an Honorary Fellow of the American College of Radiology in 1988. His main interests are in the radiotherapy of Head and Neck cancer.