Hepatocarcinogenesis: A Polygenic Model of Inherited Predisposition to Cancer

The Prevalence of Cancer: A Review of the Available Data

Aims and Background

Cancer prevalence in a population, defined as the proportion – or the number – of people who were diagnosed with a cancer during their lives and are still alive at a given date, is a crucial indicator for heath care planning and resource allocation. Long-term population-based cancer registries (CR) are the appropriate tools to produce prevalence figures, which, however, are scarcely available. This paper contains a review up to 1999 of the published data world-wide (reports and articles) on cancer prevalence: including measured and estimated figures.

Materials and Methods

Data on cancer prevalence from CRs are available for the Nordic countries, Connecticut, and Italy. In addition, electronic data are available for the European Union (EU). Data for the Nordic countries were first published in the mid-seventies, reporting the prevalence for 1970. The first data from Connecticut were available 10 years later. Estimates for all EU countries were published by the International Agency for Research on Cancer (IARC) in 1997. In Italy, observed and estimated data on the prevalence of respiratory and digestive tract cancer and breast cancer have been published during the nineties, followed by a systematic analysis for all cancers in 1999. By using information obtained from CRs, cancer prevalence data were calculated directly (observed prevalence) by means of incidence and follow-up information on individual cancer patients, or indirectly (estimated prevalence) by means of mathematical models, which generally use epidemiological information at the aggregate level.

Results

Cancer prevalence for all cancers combined (proportions per 100,000 inhabitants) showed values of less than 700 in males and less than 800 in females in 1970 (Finland) to over 2,300 in males and over 3,000 in females in 1992 (Italian registries). With few exceptions, in each country and period considered the cancer sites contributing most to cancer prevalence are lung, colon-rectum, prostate and bladder in males, colon-rectum, breast, uterus (both cervix and corpus) and ovary in females. At present, comparison of measurements from different areas is difficult because there exists no standardized mode of presentation.

Conclusions

In spite of their being potentially useful for health care planning, prevalence data have been produced inconsistently and late by cancer registries, at least in comparison with the systematic availability of incidence and survival statistics. The available data can be compared only to a limited extent due to differences in completeness, in the choice of indicators, in the standard populations, and in the frequency of publication. It would be desirable that in the future data will be produced systematically, with a higher level of standardization compared to the past, and, most importantly, on the same geographic and administrative scale as health-care decision-making.

Risk of HCC: genetic heterogeneity and complex genetics

Hepatocellular carcinoma (HCC) is a common form of cancer that arises from hepatocytes and whose risk may be affected by several known environmental factors, including hepatitis viruses, alcohol, cigarette smoking, and others. Rare monogenic syndromes, such as alpha1-antitrypsin deficiency, glycogen storage disease type I, hemochromatosis, acute intermittent and cutanea tarda porphyria, as well as hereditary tyrosinemia type I are associated with a high risk of HCC. Several common conditions or diseases inherited as polygenic traits e.g. autoimmune hepatitis, type 2 diabetes, a family history of HCC, hypothyroidism, and non-alcoholic steatohepatitis also show an increased risk of HCC compared to the general population. Overall, the genetic susceptibility to HCC is characterized by a genetic heterogeneity; a high individual risk of HCC may thus be caused by several unlinked single gene defects, whose carriers are rare in the general population, or by more common conditions inherited by complex genetics.

Genetic control of resistance to hepatocarcinogenesis by the mouse Hpcr3 locus

The genome of the BALB/c mouse strain provides alleles that dominantly inhibit hepatocellular tumor development in F1 crosses with the highly hepatocarcinogenesis-susceptible C3H/He strain. Genome-wide linkage analysis using a 1536-single-nucleotide polymorphism array in a (C3H/He x BALB/c)F2 intercross population treated with urethane to induce hepatocellular tumor development revealed a locus with a major role in the resistance to hepatocarcinogenesis. This locus, designated hepatocarcinogen resistance 3 (Hpcr3) and mapping to central chromosome 15, showed a linkage at LOD score = 16.52 and accounted for 40% of the phenotypical variance. The BALB/c-derived allele at Hpcr3 reduced tumor-occupied area of the liver up to 25-fold, in a semidominant way. Additional minor loci were mapped to chromosomes 1, 10, and 18. A gene expression profile of normal adult mouse liver showed a significant association with susceptibility of BALB/c, C3H/He, and F1 mice to hepatocarcinogenesis and identified the genes expressed in the Hpcr3 locus region; moreover, this analysis implicated the E2F1 pathway in the modulation of the phenotype susceptibility to hepatocarcinogenesis.

CONCLUSION

These findings, indicating the complex genetics of dominant resistance to hepatocarcinogenesis, represent a step toward the identification of the genes underlying this phenotype.

CO2 laser surgery: A larynx preservation alternative for selected hypopharyngeal carcinomas

BACKGROUND

Transoral CO2 laser surgery (TLS) has demonstrated good oncologic results and low morbidity in the treatment of selected laryngeal carcinomas, but experience in hypopharyngeal carcinomas (HC) is limited. The aim of this study was to evaluate the usefulness of TLS in the treatment of selected HC.

METHODS

Twenty-eight patients with HC were treated with TLS and neck dissection. Tumors with preoperative invasion of thyroid cartilage at CT, deep growth into the cervical space or tongue base, and tumors crossing the posterior midline or involving the cervical esophagus were excluded. Postoperative radiation to the neck was administered when more than one lymph node was involved, when the metastasis diameter was greater than 2 cm, or when extranodal spread was found at the pathologic study.

RESULTS

The sample included two T1, 16 T2, nine T3, and one T4 tumors. Stage classification was: II, 21.4%; III, 28.6%; and IV, 50%. Four-year overall and disease-specific survival rates were 43.4% and 59.4%, respectively, with 78.5% function preservation. Nine patients (32.1%) did not need a nasogastric feeding tube. The mean duration of the feeding tube in the remaining patients was 15.27 +/- 27.3 days. We had two postoperative bleeding episodes that required endoscopic coagulation and three postoperative pneumonias caused by aspiration.

CONCLUSIONS

TLS is an alternative for the treatment of selected HC associated with a high larynx preservation rate.

Estimation and projections of cancer prevalence from cancer registry data

A method, PIAMOD (Prevalence, Incidence, Analysis MODel), which allows the estimation and projection of cancer prevalence patterns by using cancer registry incidence and survival data is presented. As a first step the method involves the fit of incidence data by an age, period and cohort model to derive incidence projections. Prevalence is then estimated from modelled incidence and survival estimates. Cancer mortality is derived as a third step from modelled incidence, prevalence and survival. An application to female breast cancer is given for the Connecticut State by using data from the Connecticut Tumor Registry (CTR), 1973-1993. The age, period and cohort model fitted incidence quite well and allowed us to derive long-term projections up to 2030. Patients' survival was also projected to future years according to a scenario approach based on two extreme hypotheses: steady, that is, no more improvements after 1993 (conservative), and continuously improving at the same rate as during the observation period. Age-standardized estimated incidence shows a changing trend around the year 2005, when it starts decreasing. Age-standardized prevalence is expected to increase and change trend at a later date. Breast cancer mortality is projected as decreasing, as the combined result of no further increase in incidence and improving cancer patients' survival. An easy-to-use PIAMOD software package, on which work is in progress, will be made available to individual cancer registries and/or health planning institutions or authorities once it is developed. The use of the PIAMOD method for cancer registries will allow them to provide results of paramount importance for the whole community involved in the assessment of future disease burden scenarios in an evolving society.

Cell-mediated immune system regulation in periodontal diseases

The adaptive immune system consists of humoral and cell-mediated immunity. T-lymphocytes are the key components of cell-mediated immunity. CD4+ helper T-lymphocytes facilitate B-cells to differentiate and produce specific antibodies, whereas CD8+ cytotoxic T-lymphocytes kill virally infected cells. Periodontal diseases have been associated with a variety of imbalances in the regulation of immune responses. Changes in the ratios of peripheral blood CD4+ and CD8+ T-lymphocytes, depressed proliferative responses of peripheral blood lymphocytes, and increased frequency of CD45RO+ memory T-lymphocytes in diseased tissues have been reported in individuals with various forms of periodontal disease. While some studies have shown an increased frequency of gamma delta + T-cells in periodontal lesions, the role of gamma delta + T-cells in periodontal disease remains controversial. The ability of putative periodontopathic bacteria selectively to stimulate certain V beta-expressing T-cells is intriguing and could determine whether a CD4+ Th1 or a CD4+ Th2 cell response is elicited. The prominence of a particular subset of helper T-cells within the periodontal lesion could be a reflection of the stage and activity of the disease, or the types of bacteria present. Regardless, longitudinal studies of the involvement of T-cell subsets and cytokines in periodontal disease are clearly needed.