Trends in cancer mortality, 1955-1989: Asia, Africa and Oceania

Risk factors for ovarian cancer: an overview with emphasis on hormonal factors

Ovarian cancer is the fifth most frequently occurring cancer among women and leading cause of gynecological cancer deaths in North America. Although the etiology of ovarian cancer is not clear, certain factors are implicated in the etiology of this disease, such as ovulation, gonadotropic and steroid hormones, germ cell depletion, oncogenes and tumor suppressor genes, growth factors, cytokines, and environmental agents. Family history of breast or ovarian cancer is a prominent risk factor for ovarian cancer, with 5-10% of ovarian cancers due to heritable risk. Reproductive factors such as age at menopause and infertility contribute to greater risk of ovarian cancer, whereas pregnancy, tubal ligation, and hysterectomy reduce risk. Oral contraceptive (OC) use has clearly been shown to be protective against ovarian cancer. In contrast, large epidemiologic studies found hormone replacement therapy (HRT) to be a greater risk factor for ovarian cancer. The marked influence of hormones and reproductive factors on ovarian cancer suggests that endocrine disrupters may impact risk; however, there is a notable lack of research in this area. Lifestyle factors such as cigarette smoking, obesity, and diet may affect ovarian cancer risk. Exposure to certain environmental agents such as talc, pesticides, and herbicides may increase risk of ovarian cancer; however, these studies are limited. Further research is needed to strengthen the database of information from which an assessment of environmental and toxicological risk factors for ovarian cancer can be made.

Dietary garcinol inhibits 4-nitroquinoline 1-oxide-induced tongue carcinogenesis in rats

The effects of dietary feeding with a polyisoprenylated benzophenone, garcinol, isolated from Garcinia indica fruit rind on the development of 4-nitroquinoline 1-oxide (4-NQO)-induced oral carcinogenesis were investigated in male F344 rats. At 7 weeks of age, animals were given 4-NQO at 20 ppm in the drinking water for 8 weeks to induce tongue neoplasms. They also received the diets containing 100 or 500 ppm garcinol either during (for 10 weeks) or after (for 22 weeks) the carcinogen exposure. The other rats were given tap water without 4-NQO throughout the experiment, and fed garcinol (500 ppm)-containing diet or basal diet alone. At the end of the study (week 32), incidences of tongue neoplasms and preneoplastic lesions, cell proliferation activity in the normal-like tongue epithelium estimated by 5-bromodeoxyurideine (BrdU)-labeling index and cyclin D1-positive cell ratio, and immunohistochemical expression of cyclooxygenase-2 (COX-2) in the tongue lesions were determined. Dietary garcinol significantly decreased the incidence and multiplicity of 4-NQO-induced tongue neoplasms and/or preneoplasms as compared to the control diet. Dietary administration of garcinol also significantly reduced the BrdU-labeling index and cyclin D1-positive cell ratio, suggesting reduction in cell proliferation activity in the tongue by garcinol. The COX-2 expression in the tongue lesions was also suppressed by feeding with garcinol. These results indicate that dietary administration of garcinol inhibited 4-NQO-induced tongue carcinogenesis through suppression of increased cell proliferation activity in the target tissues and/or COX-2 expression in the tongue lesions.

Mortality from cutaneous malignant melanoma in Europe. Has the epidemic levelled off?

Trends of mortality from cutaneous malignant melanoma (CMM) between 1960 and 1999 in several European countries and the European Union (EU) as a whole have been reviewed, using death certification data for skin cancer available from the World Health Organization. Separate analyses were performed for young (i.e., age 20-44 years) and middle-aged (i.e., age 45-64 years) adults, among whom around 80-90% of skin cancer deaths are attributable to CMM. After steady rises between 1960 and 1990, skin cancer rates among young adults have tended to decline since the mid-1990s in several European countries, with a fall of 14% in men and of 11% in women in the EU as a whole. In middle-aged adults, the trends were less favourable, although mortality started to level off since the mid-1990s. Thus, our data provide further evidence of an improvement of CMM mortality trends in recent years in several European countries. The particularly favourable trends in young people suggest that a further decline in mortality from CMM in Europe is likely to occur within the next few years.

Inhibitory effects of troglitazone, a peroxisome proliferator-activated receptor gamma ligand, in rat tongue carcinogenesis initiated with 4-nitroquinoline 1-oxide

Ligands for peroxisome proliferator-activated receptor (PPAR) gamma have been implicated in growth inhibition and cell differentiation in certain malignancies. In this study, the effects of troglitazone, a PPAR gamma ligand, given during the postinitiation phase of oral carcinogenesis initiated with 4-nitroquinoline 1-oxide (4-NQO) were investigated in male F344 rats. Rats aged 6 weeks were given 4-NQO at 20 ppm for 8 weeks to induce tongue neoplasms. Starting 1 week after the cessation of 4-NQO exposure, animals were fed diets containing 0, 30 or 100 ppm troglitazone for 22 weeks. At the end of the study (week 32), the incidences of 4-NQO-induced tongue neoplasms and preneoplasms were determined histopathologically and cell proliferation activity was estimated by counting bromodeoxyuridine (BrdU)-labeling indices and cyclin D1-positive cell ratios. In addition, immunohistochemical expression of cyclooxygenase (COX)-2 and PPAR gamma was assessed in the tongue lesions. Feeding with 100 ppm troglitazone significantly decreased the incidence of squamous cell carcinoma when compared to the group without troglitazone treatment (5.0% vs. 45.8%, P < 0.005). Interestingly, the BrdU-labeling index and cyclin D1-positive cell ratio assessed in the non-lesional tongue squamous epithelium were reduced by dietary administration of troglitazone (P < 0.0001-0.005). Additionally, the immunoreactivity of COX-2 in the tongue lesions was also decreased by the treatment (P < 0.01-0.05). These results clearly showed that dietary troglitazone inhibits 4-NQO-induced tongue carcinogenesis and such inhibition is related to suppression of increased cell proliferation and/or COX-2 expression. This study warrants further investigation on the use of PPAR gamma ligands as a novel preventive approach for oral malignancy.

Epidemiology of ovarian cancer: a summary review

Ovarian cancer is among the five leading sites for cancer incidence and mortality in women from developed countries. Its incidence and mortality rates have, however, been declining over the last few decades following the introduction of oral contraceptives, which - together with parity - are the best recognized protective factor for the disease. Late menopause and irregular menstrual cycles may also reduce the risk, while the role of hormone replacement therapy in menopause and fertility treatments is still unclear. Cosmetic talc use and some aspect of diet (i.e. saturated fats, refined carbohydrates) have been associated with increased risk, in some--though not all--studies), while vegetable consumption appears to be inversely related to risk. These issues remain open to debate. Women with a family history of ovarian and breast cancer in first-degree relatives are also at increased risk, but family history accounts for only 4-5% of cases. Most ovarian cancers are therefore environmental in origin and consequently, at least in principle, avoidable.

Trends in incidence and prognosis of the histological subtypes of lung cancer in North America, Australia, New Zealand and Europe

BACKGROUND

Since the incidence of the histological subtypes of lung cancer in industrialised countries has changed dramatically over the last two decades, we reviewed trends in the incidence and prognosis in North America, Australia, New Zealand and Europe, according to period of diagnosis and birth cohort and summarized explanations for changes in mortality.

METHODS

Review of the literature based on a computerised search (Medline database 1966-2000).

RESULTS

Although the incidence of lung cancer has been decreasing since the 1970s/1980s among men in North America, Australia, New Zealand and north-western Europe, the age-adjusted rate continues to increase among women in these countries, and among both men and women in southern and eastern Europe. These trends followed changes in smoking behaviour. The proportion of adenocarcinoma has been increasing over time; the most likely explanation is the shift to low-tar filter cigarettes during the 1960s and 1970s. Despite improvement in both the diagnosis and treatment, the overall prognosis for patients with non-small-cell lung cancer hardly improved over time. In contrast, the introduction and improvement of chemotherapy since the 1970s gave rise to an improvement in - only short-term (<2 years) - survival for patients with small-cell lung cancer.

CONCLUSIONS

The epidemic of lung cancer is not over yet, especially in southern and eastern Europe. Except for short-term survival of small cell tumours, the prognosis for patients with lung cancer has not improved significantly.

Comparison of cancers of the oral cavity and pharynx worldwide: etiological clues

We assessed separate and combined sex-specific incidence rates of oral and pharyngeal cancer for 1988-92 and oral/pharyngeal ratios from 49 different cancer registries in five continents. Incidence trends over a period of approximately 30 years were evaluated in 16 long active registries for men and four for women. Cancers of the lip, salivary glands, and nasopharynx were excluded. The incidence of both oral and pharyngeal cancer among men is highest in northern France, southern India, a few areas of central and eastern Europe, and Latin America. Among women, the highest incidence is observed in India. Oral/pharyngeal ratio is everywhere systematically lower in men compared to women. Recent trends for oral cancer are more favourable than those for pharyngeal cancer in developing countries. In developed countries, trends in oral cancer appears to be more closely correlated to changes in alcohol consumption than those of pharyngeal cancer.

Human papillomavirus in head and neck squamous cell carcinoma: are some head and neck cancers a sexually transmitted disease?

There is abundant epidemiologic and virologic evidence that high-risk human papillomaviruses (HPVs) are tumorigenic in human epithelia, particularly in the cervix, where HPV infection is necessary for cancer development. HPV DNA has been detected in a proportion of head and neck squamous cell carcinomas (HNSCCs) in numerous case series. The mere presence of the virus in tumor specimens, by itself, does not imply a causal relationship. However, recent studies support an etiologic role for HPVs in a subset of HNSCC, particularly poorly differentiated tumors arising from Waldeyer's tonsillar ring. Epidemiologic studies have shown that exposure to HPV increases the risk of HNSCC, and HPV infection may interact with alcohol and tobacco exposure in tumor promotion. Molecular studies indicate that transcriptionally active virus is confined to tumor cells. It will be important to clarify further the role that HPV has in HNSCC development, because HPV-based therapeutic vaccines which are currently being developed for cervical cancer may also be of benefit in the management of HNSCC.

Recent declines in worldwide mortality from cutaneous melanoma in youth and middle age

Trends in age-standardised death-certification rates for skin cancer [mainly cutaneous malignant melanoma (CMM)] over the period 1955-1995 were considered for 22 developed countries (18 from Europe, Canada, the United States, Australia and New Zealand) on the basis of the World Health Organization database. Between 1955 and 1984, mortality from CMM has been rising in both young adults (20 to 44 years) and middle aged population (45 to 64 years) in most European countries, North America and Australia. Between 1985 and 1995, CMM mortality rates were still rising in several countries for middle-aged males, though, to a lesser extent, they were more favourable in middle-aged women and declined in young adults in most countries, particularly in northern Europe.

Schistosomiasis and the risk of bladder cancer in Alexandria, Egypt

The relationship between history of schistosomiasis and bladder cancer risk was investigated using data from a case-control study conducted between January 1994 and July 1996 in Alexandria, Egypt. Cases were 190 subjects with incident, histologically confirmed invasive cancer of the bladder, and controls were 187 subjects admitted to hospital for acute, non-neoplastic, non-urinary tract conditions. Eighty-six cases (45%) vs 69 controls (37%) reported a history of urinary schistosomiasis. The corresponding multivariate odds ratio (OR) of bladder cancer -- after allowance for age, sex, education, smoking, other urinary infections and high-risk occupations -- was 1.72 (95% confidence interval (CI) 1.0-2.9). The ORs were 0.22 (95% CI 0.1-0.4) for intestinal schistosomiasis and 0.32 (95% CI 0.1-1.9) for schistosomiasis of other types. The OR for urinary schistosomiasis was higher in subjects who were younger at first diagnosis (OR of 3.3 for <15 years) and in those with a long time since first diagnosis (OR of 3.0 for > or = 35 years). The ORs were 15.8 for male ever-smokers with a history of urinary schistosomiasis, compared with never-smokers without such a history, and 3.2 for men ever-infected with urinary Schistosoma haematobium and ever-employed in high-risk occupations, compared with those never-infected and with no high-risk occupational history. This study confirms that clinical history of urinary schistosomiasis is significantly, but modestly, associated with increased bladder cancer risk, explaining some 16% of bladder cancer cases in this Egyptian population.

Epidemiology and prevention of oral cancer

Descriptive epidemiology of oral and pharyngeal cancer over the last four decades is reviewed, with specific focus on Europe. Substantial rises in mortality rates have been observed for younger males, mostly in eastern Europe. The independent role of alcohol and tobacco and their interaction on oral carcinogenesis is discussed, since these factors account for about three quarters of oral cancers in Europe. The influence of dietary factors, and in particular of a diet poor in fresh fruit and vegetables on oral carcinogenesis, is also discussed, since diet may account for 10-15% of oral cancer cases in Europe. Finally, among other carcinogens, the possibility of human papillomavirus involvement in the aetiology of cancer of the oral cavity and pharynx is overviewed. Implications for prevention are discussed.

Diet diversity and gastric cancer

It has long been suggested that a varied diet may protect against gastric cancer, in the absence, however, of definition and quantification of the issue. Thus, we considered the relationship between diet diversity (i.e., variety of food intake computed as the total number of foods consumed at least once per week) and the risk of gastric cancer using data of a case-control study conducted between 1985 and 1993 in northern Italy on 746 gastric-cancer cases below age 75 years and 2,053 controls admitted to hospital for acute, non-neoplastic, non-digestive-tract diseases. A significant inverse association was observed between various measures of food diversity and gastric cancer risk. Compared with subjects in the lowest quartile of total diversity, the multivariate odds ratios (ORs) were 0.9 for the second, 0.9 for the third and 0.7 for the highest quartiles. The inverse association was even stronger for vegetable (OR = 0.5 for the highest level) and fruit (OR = 0.6) diversity. Our findings were not explained by allowance for total calorie intake and total number of servings, besides education as an indicator of social class, and support, therefore, the concept that a more diversified and richer diet is a relevant underlying correlate of the decline in gastric cancer rates.

Chemopreventive effect of a xanthine oxidase inhibitor, 1'-acetoxychavicol acetate, on rat oral carcinogenesis

The effect of a xanthine oxidase inhibitor, 1'-acetoxychavicol acetate (ACA), on 4-nitroquinoline 1-oxide (4-NQO)-induced oral carcinogenesis was investigated in male F344 rats. All rats except those in the ACA-alone and untreated groups were given 4-NQO (20 ppm) In the drinking water for 8 weeks to induce oral cancer. Starting 1 week before the 4-NQO exposure, animals were fed diet containing 100 ppm or 500 ppm ACA for 10 weeks, followed by the basal diet without ACA for 22 weeks. Other groups were fed the diet containing ACA at 100 ppm or 500 ppm for 22 weeks, starting 1 week after the cessation of 4-NQO exposure. The remaining groups consisted of rats given 500 ppm ACA alone or untreated rats. At the termination of the experiment (32 weeks), the incidences of tongue neoplasms and preneoplastic lesions, polyamine levels in the tongue tissue, and cell proliferation activity estimated in terms of 5-bromodeoxyuridine (BrdU)-labeling index and by morphometric analysis of silver-stained nucleolar organizer regions' protein (AgNORs) were compared among the groups. Feeding of ACA at the two doses during initiation or postinitiation significantly decreased the development of tongue carcinoma (93-100% reduction, P < 0.001) and preneoplasia (43-50% reduction for hyperplasia and 34-48% reduction for dysplasia, P < 0.05). There were no such lesions in rats fed ACA alone or those in the untreated control group. The number of AgNORs per cell nucleus was significantly decreased by feeding of ACA at a high dose (500 ppm) (29% inhibition, P < 0.05). The BrdU-labeling index was also reduced by dietary administration of ACA (23-32% inhibition, P < 0.01). In addition, ACA feeding reduced tongue polyamine levels (35-40% inhibition, P < 0.05). These results indicate that ACA inhibited rat oral carcinogenesis, and such inhibition might be related to suppression of cell proliferation in the oral mucosa by the xanthine oxidase inhibitor.

Chemoprevention of digestive organs carcinogenesis by natural product protocatechuic acid

The worldwide increase in cancer mortality demands a practical and effective chemopreventive approach to this problem. Using animal bioassay, the authors demonstrated protocatechuic acid (PCA, 3,4-dihydroxybenzoic acid), a simple and antioxidative phenolic acid present in fruits, vegetables, and nuts, to be an efficacious agent in reducing the carcinogenic action of 4-nitroquinoline 1-oxide in oral cavity, N-methyl-N-nitrosourea in glandular stomach, azoxymethane in colon, and diethylnitrosamine in liver. PCA exerts its chemopreventive action partly through inhibition of cell proliferation induced by carcinogens in the target organs. The prospect of this agent as chemopreventive against human cancer warrants a thorough investigation, such as dose-dependent efficacy and its potential toxicity at an effective dose level in other species of animals. Considering its promising anticarcinogenic potency, proliferation biomarkers, including tissue and blood polyamine levels, might eventually be useful in assessing the possible role of PCA intake in high risk populations for cancers of these organs.

Incidence, mortality and survival from invasive cervical cancer in Vaud, Switzerland, 1974-1991

BACKGROUND

Several factors have contributed to the substantial decline in mortality from cervical cancer registered in most areas of the world, i.e., improved sexual hygiene, changes in reproductive factors, cervical screening, and, possibly, improved treatment. Each of these components is evaluated through a systematic inspection of trends in incidence, mortality and survival rates registered for a well-defined population.

PATIENTS AND METHODS

Trends in incidence, mortality and survival from invasive cervical cancer over the period 1974-1991 were analysed for three separate age groups (< 55, 55-64, > or = 65 years), histological type and stage using data from the Cancer Registry of the Swiss Canton of Vaud.

RESULTS

Below age 55, the age-standardized (world standard) incidence rate was 9.3/100,000 women in 1974-76, it declined steadily thereafter down to 2.9 in 1986-88, but increased to 4.3 in 1989-91. In the age group 55-64, cervical cancer incidence remained around 40/100,000 to the end of the 1970s, but thereafter declined to 10.9 in 1989-91. No consistent trend was observed in elderly women, and the rate in 1989-91 (26.7/100,000) was similar to that in 1974-76 (33.7). The overall age-standardized cervical cancer incidence declined from 13.5/100,000 in 1974-76 to 5.8 in 1986-88, but rose to 6.4 in 1989-91. A similar pattern was observed for mortality, with a fall in rates in younger women between 1974 and 1985 (from 2.1 to 0.6/100,000), and a subsequent rise to 1.1/100,000 in 1989-91. A substantial decline in mortality was observed in women aged 55 to 64 since the early 1980's, from 17.2 in 1980-82 to 3.3 in 1989-91. No clear mortality trend was evident in older women. Overall, cervical cancer mortality declined from 4.3/100,000 in 1974-76 to 2.3 in 1989-91. The five-year relative survival rates were around 0.70-0.75 for younger women, around 0.60 for those aged 55 to 64, and 0.50 for elderly ones. In a Cox proportional hazard model, age and clinical stage were significantly related to survival, but not histological type and calendar period of diagnosis. No substantial change in survival from invasive cervical cancer was observed over the 18-year period considered, nor was there any notable change in the stage distribution over time. The proportion of adenocarcinomas, however, appears to have increased in the most recent calendar period.

CONCLUSIONS

These data reflect the impact of screening on cervical cancer rates, which, however, appeared restricted to women below age 65. An upward trend in cervical cancer incidence and mortality rates for younger women was also apparent, and there was no indication from these data of an improved survival for invasive cervical cancer patients over the last two decades. Extention of screening to elderly women appears to be a priority for reducing cervical cancer rates in this population.