Happenings in histopathology - a post-World War II perspective.

There have been several important developments in the practice of histopathology since World War II; those reviewed in this lecture are grouped under 4 headings: new techniques (cytopathology, electron microscopy, immunohistochemistry and molecular pathology), organisational issues (recruitment, training and certification, subspecialties, quality control and consultations), ethical and legal issues (service costs, and the ownership and uses of biopsy tissues) and globalisation (international associations, standardised classification and nomenclature, and telepathology). Advances in the fields of molecular pathology and telepathology are expected to have the greatest impact on the practice of pathology in the next decade.

Immunogenetic aspects of nasopharyngeal carcinoma. IV. Increased risk in Chinese of nasopharyngeal carcinoma associated with a Chinese-related HLA profile (A2, Singapore 2).

The results of this study of 110 Singapore Chinese with nasopharyngeal carcinoma (NPC) and 91 controls confirmed the association between the occurrence of HLA antigen Singapore 2 (Sin2) and NPC in the Chinese population, and indicated that their increased risk for NPC was confined to the joint occurrence of Sin 2 and A2 antigens. These findings suggested that the genotype of importance in susceptibility to NPC is the A2-Sin 2 haplotype.

2005 Distinguished Academician Lecture: Evolution of postgraduate medical education in Singapore--role of professional associations.

From 1910 to 1945, doctors in Singapore received postgraduate training through apprenticeship. During the early post-war period, some doctors in the public service were given scholarships to study in Britain and to obtain higher professional qualifications from the British Royal Colleges. The events that most influenced subsequent development of postgraduate education in Singapore occurred between 1956 and 1969: the formation of the Academy of Medicine and the Singapore Medical Association (SMA); organisation of courses for candidates preparing for examinations of the Royal Australasian and British Colleges; competition between the Academy and the University over responsibility for postgraduate medical education; the inauguration of the School of Postgraduate Medical Studies (SPMS); and the introduction of Master of Medicine (M Med) degrees in various medical specialties. From 1970 to 1999, there was expansion in several aspects of postgraduate medical education: SPMS awarded more than 2000 M Med degrees; the Singapore Medical Council (SMC) established a Register of Specialists and formed a Specialist Accreditation Board; the Academy formed Chapters in 10 specialties and developed Advanced Specialty Training programmes leading to Fellowship of the Academy of Medicine Singapore (FAMS); the SMA formed Societies in some 20 specialties; and a College of Family Physicians was inaugurated. There have been more developments from 2000 to 2005: the University restructured SPMS as a Division of Graduate Medical Studies within the Faculty of Medicine; the SMC implemented compulsory Continuing Medical Education; and the Academy converted 6 of its 10 Chapters into Colleges.

Immunodeficiency to hepatitis B virus infection and genetic susceptibility to development of hepatocellular carcinoma.

The high frequency of hepatitis B antigen (HBsAg) in hepatocellular carcinoma (HCC) patients has led to the hypothesis that immunoresponsiveness to hepatitis B virus (HBV) may be deficient in some patients, and that the immune response deficiency may have a genetic basis. Radioelectrocomplexing (REC), a radioimmunoassay in gel based on the principle of counterimmunoelectrophoresis (CIE), has been used to identify four HBV immune status subgroups: 1) HBsAg +ve/HBsAb +ve; 2) HBsAg +ve/HBsAb -ve; 3) HBsAb -ve/HBsAb +ve; 4) HBsAg -ve/HBsAb -ve/HBsAb -ve. These subgroups comprise 2, 6, 70, and 22 percent, respectively, among blood donors, and 32, 19, 23, and 26 percent, respectively, among HCC patients. Although the HBV exposure rates in the two groups were similar, the immune complexemic rates and HBs antigenemic rates were significantly higher in HBB patients than in the blood donors. It is proposed that the failure of termination of HBV infection revealed by these high rates reflects an immunodeficiency state characterized by an inability to produce high-avidity HBsAb. The immunodeficiency might have a primary genetic basis, or it might be secondary to the immunodepressive effects of concurrent viral or parasitic infections.

Teratoid carcinosarcoma of the paranasal sinuses.

Malignant tumours with teratoid or blastomatous features are exceptionally rare in the upper respiratory tract with only 8 documented cases, including the 3 in this report. The tumours occurred in adults aged 27 to 62 yr, and the sites of origin were the ethmoid sinus (4 cases), ethmoid and other paranasal sinuses (2 cases), unspecified sinuses (1 case) and nasopharynx (1 case). The disease was rapidly fatal in 3 cases in which treatment was restricted to surgery and was associated with longer survivals in those given supportive radiotherapy. The tumours are locally aggressive and may invade soft tissues, bone, orbit and cranial cavity. Histologically, the tumours are characterized by a mixture of epithelial and mesenchymal components including cellular elements with immature or embryonal characteristics. These tumours, variously termed malignant teratoma, blastoma, teratocarcinoma or teratoid carcinosarcoma, probably comprise a homogeneous group of neoplasms since their histological and biological features are essentially similar. It is postulated that the tumours develop from primitive embryonic tissues or pluripotential cells that have remained sequestered in the sinonasal tract.

Nasopharyngeal carcinoma: epidemiology, histopathology and aetiology.

The highest incidence of nasopharyngeal carcinoma (around 20 per 100,000 per year) is found in Chinese populations in many countries. Elevated rates (5--15) are found in Eskimos, and in several racial groups in South-East Asia. The incidence rates in Malta and in some parts of Northern Africa are also moderately elevated. The incidence rates are low (less than 1) in virtually all other parts of the world. In Singapore, the incidence rates are high in Chinese (18.4), intermediate in Malays (4.7) and low in Indians (less than 1). Among the various Chinese communities, the incidence rates in Cantonese (29.1 and 11.0 for males and females respectively) are significantly higher than those in Hokkiens (14.1 and 4.7), Teochews (18.3 and 6.2), Hainanese (14.2 and 3.3) and Hakkas (12.6 and 4.8). The tumour has a male preponderance (2--3 times) and a peak incidence in the 5th and 6th decades. Nasopharyngeal carcinoma (NPC) is the commonest form of nasopharyngeal cancer in man. All histological types of NPC have consistently shown ultrastructural evidence of squamous differentiation and may be regarded as variants of a homogeneous group of tumours. The development of the neoplasm is attributable to the action of environmental factors in genetically susceptible persons. There is growing evidence that nitrosamine compounds and the Epstein-Barr virus may be involved in the aetiology of this neoplasm.

Cancer Epidemiology.

The methods of epidemiological studies of cancer in man are discussed briefly with reference to sources of information and the clues they may provide to cancer aetiology. Some of the features of the cancer patterns in Singapore are presented. Geographical and racial variations in cancer incidence and their possible determinants are discussed and tabulated.

Epidemiology or primary liver cancer in Singapore.

Primary Liver Cancer occurs with high frequency in most parts of the East and South East Asia. The age standarised rates for most Western countries are below 2 per 100,000 per year for males and below 1 for females. In Singapore, the rate is 29.1 for males and 7.7 for females. There is a male preponderance in Singapore by a ratio of male to female of 3.8 in age standardised incidence rates. The peak incidence is the 6th decade (30.1% of cases) and in the 7th decade (31.7% of cases). The Chinese have the highest incidence amongst the different ethnic races. Epidemiological studies done on migrant population strongly suggest that environmental factors are more important than genetic factors in the aetiology of liver cancer.

Trends and ethnic variation in incidence and mortality from cancers of the colon and rectum in Singapore, 1968 to 1982.

Data collected by the population-based Singapore Cancer Registry show rapidly increasing incidence for both cancer of the colon (annual average of 3-6%) and rectum (annual average of 3-5%) over the period 1968 to 1982. The cancer incidence rates were generally highest among the Chinese in whom the latest age-adjusted rates (1978-82) for colon were 14.3 per 100,000 in males and 14.9 in females, and for rectum 12.5 in males and 10.0 in females. The rates were intermediate for Indians and lowest in Malays. In both sexes, foreign-born Singapore Chinese (mostly born in China) had significantly lower risks for colon cancer compared to local-born Chinese (RR 0.71 in males, RR 0.72 in females, both p less than 0.05). There were no discernible differences between the two groups for rectal cancer. Internationally, Singapore's incidence rates for both sites rank roughly midway between the lows of Asia and Eastern Europe and the highs of Western Europe, North America and New Zealand. Among Chinese populations worldwide, the Singapore rates are also intermediate between the low rates in Shanghai and the high rates in Hawaii and California. The rates among Singapore Indians are generally higher than those in Bombay, Madras and Bangalore. These findings strongly suggest the importance of environmental lifestyle related risk factors among which, on current knowledge, dietary intakes feature prominently. The per capita food availability in Singapore especially in meat and animal fat, has also increased markedly over the last two decades.(ABSTRACT TRUNCATED AT 250 WORDS)

Cancer incidence in Singapore, 1998 to 1999.

The age-standardised incidence rates for all cancers for 1998-1999 were 235.0 per 100,000 in males and 199.8 per 100,000 in females. The corresponding rates for 1993-1997 were 233.1 per 100,000 in males and 198.1 per 100,000 in females. The greatest difference was for breast cancer in females with age-standardised incidence rates increasing from 46.1 to 53.1 cases per 100,000 persons per year between these time periods. There also appears to be a shift of the peak age-specific incidence for breast cancer from premenopausal to postmenopausal years over this period. This suggests that our breast cancer incidence pattern is rapidly becoming more similar to populations in the West.