Distribution of epstein-barr virus antigenic sites on the carboxyl terminal end of ribonucleotide reductase against nasopharyngeal carcinoma serum antibodies using an immunoabsorption method.

In an attempt to clone and express proteins from the Epstein-Barr virus (EBV) cDNA library to be used as antigens in an enzyme-linked immunosorbent assay (ELISA) format to test against the antibodies found in the sera of nasopharyngeal carcinoma (NPC) patients, we have isolated and characterized three clones. All three clones expressed the same polypeptides of different lengths, which belong to the carboxyl terminal end of the large subunit of ribonucleotide reductase (RR) of the EBV genome. All three clones were found to be immunogenic and could be used in an IgA and IgG ELISA against the NPC sera with various degrees of sensitivity and specificity. Because the clones varied in length, this difference provides a simple system to determine where most of the antibody epitopes lies on the protein. We designed an immunoabsorption assay and a mathematical model to help map the segment of the polypeptide most immunogenic to 43 NPC patients. Results were unexpected: 77% of the patients were most immunogenic to region z, which was the smallest fragment among the three fragments studied. Fragment z was only 33 amino acids in length. Only 14% and 19% of patients showed the most immunogenic region in segment x and y, respectively. This variation could be due to major histocompatibility complex antigens. The patients could be divided into three groups based on the immunoabsorption assays, in which each group responded to a different immunodominant segment in the RR antigen. The largest group responded to an immunodominant segment, which was only 33 amino acids long. This domain was coded for by the gene fragment from nucleotide 78,129 to nucleotide 78,227 of the EBV genome. This segment of the protein would be suitable for further epitope mapping studies.

Strong association between hyperferritinaemia and metastatic disease in nasopharyngeal carcinoma.

We have investigated the role of serum ferritin, in relation to disease stages, in patients with nasopharyngeal carcinoma. Patients with localised disease (Ho's stage I-IV) had levels which were not significantly different from age, sex matched normal subjects and there was no relationship between mean serum ferritin levels and stage. However, in patients with metastatic disease levels were grossly elevated with mean levels increased more than 6-fold compared to normal subjects and patients with localised disease. Furthermore, among the small group of patients with localised disease but hyperferritinaemia, the subsequent development of metastatic disease within 1 year was significantly much higher (32.4%) than in those with levels falling within the reference range (10.3%). Hyperferritinaemia is strongly associated with, and may predict, metastatic disease in patients with nasopharyngeal carcinoma.

No association between HLA-DQ and -DR genotypes with nasopharyngeal carcinoma in southern Chinese.

The pathogenesis of nasopharyngeal carcinoma (NPC) is multifactorial. Associations have been reported between HLA and NPC. We studied the HLA-DR and -DQ regions on the molecular level in 136 persons (51 NPC patients and 85 healthy controls) from southern China, a particularly high-prevalence area for NPC. Restriction fragment-length polymorphism (RFLP) was used to genotype the MHC class II DR beta, DQ alpha, and DQ beta regions of the subjects. Polymerase chain reaction (PCR) using sequence-specific primer (SSP) for DQ beta genes was also performed. By RFLP, no significant difference was observed with respect to DRB, DQA, and DQB genes. By PCR SSP typing, we confirmed that there was no significant difference between NPC patients and controls with respect to DQ beta alleles. Our study suggests that HLA-DQ and -DR genes are not associated with NPC in southern Chinese and there may be other gene loci that predispose them to have such a high prevalence of the disease.

Enzyme-linked immunosorbent assay (ELISA) for IgA and IgG antibodies to Epstein-Barr-virus ribonucleotide reductase in patients with nasopharyngeal carcinoma.

661 bp coding for the carboxyl end of the large sub-unit of EBV ribonucleotide reductase was cloned into the pMal plasmid vector. Purified recombinant protein was tested in IgG and IgA ELISAs. For the IgG assay, 81 out of 100 NPC patients tested positive, whereas for the IgA assay, 60 tested positive. Among 100 normal individuals, I tested positive for the IgG assay and 9 tested positive for the IgA assay. The IgG assay picked up 6 out of 19 NPC sera which were IFA-VCA- and IFA-EA-negative for IgA antibodies. Hence the recombinant ribonucleotide reductase could have good potential as a diagnostic test for NPC or could serve as a complementary test to IFA.

Nasopharyngeal cancer treated in Singapore.

With effect from July 1987 CT-scans of the nasopharynx became routinely available in the staging of nasopharyngeal cancer (NPC) in our department. Eighty-four evaluable cases during these first six months were studied and the results at a median follow-up period of 34 months revealed that 74% were alive at 2 years. The local relapse rate were 4% for T1; 10% for T2 and 35% for T3 tumours.

Intracavitary radiotherapy for nasopharyngeal carcinoma--palliation or cure?

Although nasopharyngeal carcinoma is classically treated by external irradiation, the technique invariably results in decreased parotid secretions and rapid tooth decay. For the treatment of locally relapsed tumours, nasopharyngectomy, though effective, may not always be available for routine salvage, especially in endemic areas. A pilot study was made of ten patients having limited local relapses who were treated by intracavitary irradiation (ICI) with or without an abbreviated dose of external irradiation. With ICI alone, relapses outside the nasopharynx occurred in two patients but the combination with even an abbreviated dose of external irradiation was more successful. Nevertheless, even with relapse, patients were free from local symptoms for a median time of over two years--an excellent palliation result. More work, preferably at the multi-centre level, should be done to define more precisely the role of intracavitary irradiation for nasopharyngeal carcinoma.

Molecular cloning and expression of Epstein-Barr virus antigens in the lambda gt11 expression vector: antibodies towards proteins from the BORF2 and BKRF4 reading frames in nasopharyngeal carcinoma patients.

An easy way to clone and screen for Epstein-Barr virus antigens significant in the diagnosis of nasopharyngeal carcinoma (NPC) has been developed. Two proteins cloned and expressed as fusion proteins in lambda gt11 have been identified to be expressed from 661 bp of the BORF2 and from 500 bp of the BNKRF4 reading frames. Western blotting studies on these proteins using serum from 16 NPC and 16 normal healthy individuals showed that 15 NPC patients have either IgG or IgA antibodies towards either protein whereas only 2 normal individuals were positive. Hence, IgG and IgA antibodies towards these antigens are of diagnostic value for NPC.

Nasopharyngeal carcinoma--a review of radiotherapy techniques.

With modern megavoltage external X-ray treatment for nasopharyngeal carcinoma, results have improved but late sequelae, which are more often associated with the treatment of advanced tumours or multiple courses of external treatment, have also surfaced. Life-threatening complications include temporal lobe necrosis and hypothalamic-pituitary dysfunction. As CT scanning is superior to conventional radiography in tumour mapping, a new dedicated working staging system, catering for cross-sectional imaging parameters, is proposed for a prospective, multi-centre exercise to finalise on a badly needed common system. With it, case selection for more conservative (to minimise complications) or intensified treatments is facilitated. Intracavitary radiation has now been developed well enough for the nasopharynx. For earlier cases, based on the new staging system, this method has the potential to complement a "sub-radical" external treatment dose designed to minimise complications. A multi-centre trial is indicated. To reach cancericidal doses for the more advanced tumours coming very close to vital structures, extra machine time, though precious, is fully justified so that smaller treatment fractions delivered with facial shells for accurate reproduction of precise machine geometry and field geography can be implemented. Otherwise, subsequent management of possible serious treatment complications may cost more than the treatment itself. Various possible complications of radiotherapy and avoidance and management are outlined.

Asymptomatic temporal lobe injury after radiotherapy for nasopharyngeal carcinoma: incidence and determinants.

Computed tomography (CT) scans were performed on a cohort of 60 patients for detection of temporal lobe injury (TLI) at 1-3.5 years after radiation therapy for nasopharyngeal carcinoma. Nine cases of TLI were identified, five of which were asymptomatic. The earliest case of asymptomatic TLI was found at 2.2 years after radiation therapy and the earliest symptomatic case at 2.3 years. A significantly higher incidence of TLI was found in patients with decreased temporal lobe shielding consequent to omitted eyeshield to the anterior photon beam and in patients treated with a hyperfractionation schedule giving 67.2 Gy in 42 fractions in 6 weeks. The incidence in these subgroups at 2-3.5 years after radiation therapy was 56% (5/9 patients) and 35% (8/23 patients), respectively. No patient in this study had TLI in the absence of these two factors. The implications of the results are discussed.

High-dose-rate remote afterloading irradiation of carcinoma of the cervix in Hong Kong: unexpectedly high complication rate.

One hundred and thirty-six patients with biopsy-proven carcinoma of cervix were treated with external beam irradiation to the whole pelvis (46 Gy in 23 fractions) and three weekly applications of high-dose-rate (HDR) intracavitary brachytherapy of 7 or 8 Gy per fraction to point A (2 cm above and 2 cm lateral to the cervical os). The actuarial 5-year survival rate was 72% (Stage IB 85%; IIA 64%; IIB 70%; IIIA 25%; IIIB 53%). Patient age above 61 years and Stage III disease were adverse determinants for survival as shown by multivariate analysis. Late complications developed in 47% (65/137) of patients. Grade 3 or above complications occurred in the bladder, small bowel and sigmoid colon/rectum in 5%, 3% and 7% of patients, respectively. The most significant determinant of severe rectal complications was the addition of a lower vaginal tandem (P less than 0.01); the other determinants of rectal complications included a uterine length greater than 5 cm, a total biologically effective dose to the rectum of more than 120 Gy3 and Stage III disease.

Current problems in radiotherapy, chemotherapy and staging of nasopharyngeal carcinoma (NPC).

Nasopharyngeal carcinoma (NPC) in South East Asia is almost entirely of the undifferentiated or poorly differentiated squamous cell types which are more radiosensitive and have better prospect for locoregional control. Cross-sectional imaging can now detect disease in the parapharynx which is commonly involved by this carcinoma. This has resulted in up-staging and technique modification for better local control. Poor prognostic factors include parapharyngeal, skull bone, cranial nerve or other wide-spread involvements locally. Neck nodes in the supraclavicular fossae or bulky nodes also confer poor prognoses. A simplified staging classification system is proposed. With the availability of afterloading machines, a booster dose of intracavitary radiotherapy can conveniently be given. When given shortly after the usual external radiotherapy, the desired high dose to the primary can be achieved without increasing the risk of long-term side effects. Chemotherapy given before radiotherapy helps to achieve prompt control of bulky neck nodes which distort the anatomy and pose problems in radiotherapy dosimetry. However, the eventual survival rate is still not improved. As staging and major prognostic factors are better defined, trials of adjuvant chemotherapy given after radiotherapy should be undertaken. However, the ultimate control of NPC may rest on the feasibility studies on screening for early NPC.

Nasopharyngeal carcinoma: modes of presentation.

Nasopharyngeal carcinoma (NPC) is a common malignancy among the southern Chinese people and has a poor prognosis. The aim of this study was to describe in detail the presentation of NPC as found between 1984 and 1988 at Prince of Wales Hospital, Hong Kong. Our study confirmed that patients present with an advanced stage of malignancy; 70% were stage III to V. Eighty-two percent of patients were between 21 and 60 years of age. The symptoms often suggested benign disease and most patients would delay seeking treatment for at least 5 months. We recommend inspection of the nasopharynx with flexible nasoendoscopy for all persons in high-risk areas on a regular basis and advise a policy of active health education for both physicians and the general population to reduce the stage of NPC at first presentation.

Loss of heterozygosity on the short arm of chromosome 3 in nasopharyngeal carcinoma.

A consistent loss of constitutional heterozygosity within a specific chromosome locus in a tumor type is suggestive of a tumor suppressor gene important in the genesis of that tumor. We studied whether such genetic alterations are involved, in the development of nasopharyngeal carcinoma (NPC). Tumor and matched blood leukocytes DNA from eleven Hong Kong Chinese patients with primary NPC stages I to IV were subjected to restriction fragment length polymorphism (RFLP) analysis using chromosome 3-specific polymorphic probes. Such probes are assigned to chromosomal region 3p25 (RAF-1), 3p24-22.1 (ERBA beta), 3p21 (DNF15S2), 3p14 (D3S3), and 3q12 (D3S1). The breakpoint varied among tumors, ranging in extent from 3p21-14. However, 100% frequency of complete loss of heterozygosity was observed at two chromosomal loci: RAF-1 locus (ten of ten cases at 3p25) and D3S3 locus (nine of nine cases at 3p14), in all evaluable NPC patients, suggesting the presence of putative tumor suppressor gene(s) within or close to these defined regions. The observed consistent deletion of alleles on the short arm of chromosome 3 in the NPC cases, which is in line with our previously reported and present cytogenetic findings, may represent a critical event in the multistep genesis of NPC. The present report also identifies defined loci for linkage studies on NPC families.

Ovarian ablation failures by radiation: a comparison of two dose schedules.

Sixty Chinese breast cancer patients underwent ovarian irradiation with one of two dose schedules: 12 Gy/4 fractions/4-6 days or 14 Gy/4 fractions/4-6 days. The ovarian ablation failure rates were 14% and 0% respectively in patients above 40 years of age. The overall ablation failure rate in younger patients was unacceptably high at 35%. The significance of the findings is discussed.

Computed tomography contrast enhancement of cervical lymphadenopathy.

In a prospective study of 51 cases of lymphadenopathy (44 with cervical metastatic nasopharyngeal carcinoma, NPC) using intravenous contrast and computed tomography (CT), a ring enhancement was observed. A retrospective review of 105 cervical carcinomatous lymph nodes (64 with metastatic NPC) showed a prominent peripheral hypervascular pattern not seen in 48 lymphomas and 60 normal controls. We conclude that in carcinomatous cervical lymphadenopathy, enhancement can be achieved by intravenous contrast and CT; and the peripheral hypervascularity is the anatomical basis for the ring appearances seen radiographically.

Staging bone scintigraphy in nasopharyngeal carcinoma.

Bone scintigraphy was performed on 163 new cases of nasopharyngeal carcinoma without clinical evidence of distant metastases. Among the 10 abnormal bone scans one patient had radiographic skeletal metastases corresponding to the areas of increased tracer uptake. Two patients with abnormal bone scans subsequently developed radiographic metastases at the site of abnormal tracer uptake. The detection rate of asymptomatic skeletal metastases on presentation was thus 1.8% (3/163), and the predictive value of an abnormal scan for metastases 30% (3/10). Bone scintigraphy is not justified as a routine staging investigation for nasopharyngeal carcinoma, although it can be considered for a subset of patients considered at high risk of distant metastases.

A proposed modification of the Ho stage-classification for nasopharyngeal carcinoma.

Based on the clinical data of a retrospective study of 659 NPC patients with routine computed tomography of the nasopharyngeal region, a refinement of Ho's stage-classification for NPC is proposed with reduction in the number of overall stages without sacrificing the accuracy in predicting prognosis in the short term. Classifying the cervical lymph nodal metastasis into supraclavicular (Ho's N3) and above supraclavicular (Ho's N1 + N2) and the nasopharyngeal primary into early (Ho's T1 + T2n + T20) and advanced (Ho's T2p + T3 + T3p) forms the conceptual backbone of the present proposed modification of the original Ho stage-classification. Power in predicting the occurrence of distant metastases and the local failures has been enhanced by the proposed T-stage and N-stage re-grouping. Retrospective comparison between Ho's and the UICC stage-classifications showed a more even patients number distribution among the overall stages and a greater power in predicting NPC prognosis for the former. Prospective studies to compare the value of the different stage-classifications are required for recommendation of a single classification for general acceptance to facilitate comparison of treatment results between centres.

Soluble interleukin-2 receptors in patients with nasopharyngeal carcinoma.

The authors performed a retrospective analysis of serum soluble interleukin-2 receptor (sIL-2R) levels in 72 patients with nasopharyngeal carcinoma (NPC) using an enzyme immunoassay. Their objectives were to determine the value of serum sIL-2R in estimating the tumor burden, and its predictive value in response to therapy and prognosis. The data showed that serum sIL-2R levels in patients were significantly higher than that of healthy controls. The serum levels correlated with clinical staging and hence the tumor burden of NPC. Serial measurement of serum sIL-2R provided an accurate prognostic index of the clinical response to radiotherapy in at least 89% of patients with raised serum sIL-2R at initial diagnosis (defined as mean + 2 SD of healthy controls) and a reliable predictive index in all patients who subsequently developed distant metastasis despite initial radiotherapy. Simultaneous measurement of Epstein-Barr virus-related serology (IgA-VCA and IgG-EA) failed to demonstrate predictive value comparable with that of serum sIL-2R. The authors conclude that monitoring serum sIL-2R levels has clinical and prognostic significance in patients with NPC and that prospective studies are indicated.

Staging abdominal ultrasonography in nasopharyngeal carcinoma.

Abdominal ultrasonograms were performed on 81 unselected patients with newly-diagnosed nasopharyngeal carcinoma without clinical evidence of distant metastases. Two patients had ultrasonographic features suspicious of, but not diagnostic of, hepatic metastases. One of these two patients developed hepatic metastases six months after the examination while the other was free of metastases at follow-up 33 months afterwards. Of the 79 patients without evidence of metastases on ultrasonogram, two developed hepatic metastases after 22 and 32 months. Based on these results, we do not recommend abdominal ultrasonography as a routine staging investigation for nasopharyngeal carcinoma.