High prostate cancer mortality in Norway: Influence of Cancer Registry information?

Norway has among the highest prostate cancer mortality rates in the world. The aim of the present project was to assess whether this can be explained by the unique routine procedure of information transfer from the Cancer Registry of Norway (CR) to the Norwegian Cause of Death Registry (COD Registry). Norwegian prostate cancer patients deceased during 1996 were identified (n=2012). The information basis of the official mortality statistics was reviewed by two physicians, who independently identified the underlying cause of death, primarily prostate cancer or not, supplemented by consensus of two other physicians. The coding was done in two steps; first without, then with CR information. Project physicians identified 1063 deaths from prostate cancer as compared to the official number of 1161, with discrepancy as to prostate cancer death in 126 deceased. Information from the CR increased the project's age-adjusted (world standard population) prostate cancer mortality rate by less than 1% (from 22.7 to 22.9 per 100,000). In conclusion, the high rates of prostate cancer mortality in Norway could not be explained by information transfer from the CR to the COD Registry.

Effects of kojic acid on oxidative damage and on iron and trace element level in iron-overloaded mice and rats

Since members of hydroxypyrone series posses iron chelating properties, kojic acid (KA), 5-hydroxy-2-(hydroxymethyl)-4H-pyran-one, a fungal metabolite of natural origin, has been suggested to might play a role in iron-overload diseases and in oxidative stress conditions involving transition metal. In our experiments in vivo models of iron-overload were used to study iron-chelating properties of KA and its effect on oxidative damage in mice and rats. The treatment of iron-preloaded rats (25 mg Fe x kg(-1) b.w., i.p., daily for five days) with 0.5% KA in drinking water for four weeks did not lower the iron concentration accumulated in the liver, neither diminished the induced hepatic lipid peroxidation in iron-loaded rats. The GSH level decreased in KA-treated group. Similarly, in iron-loaded mice model experiment, the following oral treatment with KA (100 mg x kg(-1)) daily for 7 days did not decrease the level of Fe accumulated in the liver and the lipid peroxidation even enhanced after KA treatment. Though in our experiments in vivo the ability of kojic acid to affect iron kinetics in the organism could not be proved, kojic acid as a molecule of natural origin may serve as a template for the preparation of new biologically active derivatives possessing capability of chelating iron.

The effect of estradiol on the oxidative damage and trace element level determined in the liver of rats treated with dimethylarsinic acid

DMA--dimethylarsinic acid (cacodylic acid)--used as an herbicide, is the major metabolite formed after the exposure to inorganic arsenics in mammals. It is considered to have an important role in arsenic carcinogenesis through the induction of oxidative damage in various tissues. Estradiol, apart from its main hormonal effect, displays both prooxidative and antioxidative action depending on the condition of the treatment. The oxidative stress plays a crucial role in estrogen-induced carcinogenesis. In the experiments performed in female Wistar rats receiving drinking water ad libitum with 0.01% DMA for 10 weeks, one half of rats was treated with 17beta-estradiol (0.1 mg/rat s.c., twice a week) starting the 3rd week. One more group received estradiol only and last group served as controls receiving drinking water without treatment. The DMA enhanced lipid peroxidation in the liver, estradiol treatment potentiated this effect of arsenic. The GSH level was enhanced in DMA+estradiol treated group. In estradiol-only treated group both the lipid peroxidation and GSH content were increased. The administration of estradiol caused an enhancement of several trace element concentrations in the liver, mainly that of iron and copper. The critical role of estrogen on the development of oxidative stress was thus proved.

Effect of long-term storage on the concentration of albumin and free fatty acids in human sera

Stored sera from healthy persons can be used to study relationships between blood variables at the time of sampling and disease appearing several years later but storage may influence the variables. In this work we measured the concentration of albumin and free fatty acids (FFA) in samples from the JANUS serum bank of Norway. Sera from blood donors and persons participating in health screening programs have been added to the bank since 1973. The concentration of albumin and FFA was measured in 443 JANUS bank sera. The material was divided into quartiles according to the length of storage: <3 years (n = 110), 3-6 years (n = 110), 6-12 years (n = 115) and >12 years (n = 108). Albumin was measured colorometrically using the bromcresol green method and FFA was determined enzymatically. The serum albumin concentrations (mean +/- SEM) in the four groups were 55.8+/-0.6, 56.2+/-0.5, 59.9+/-0.6 and 59.5+/-0.6 g/L. The values of groups 3 and 4 were significantly higher than those of groups 1 and 2 (p<0.001). The serum FFA concentrations in the four groups were 0.56+/-0.03, 0.64+/-0.03, 0.77+/-0.03 and 0.85+/-0.04 mmol/L, i.e. a significant storage effect. The Scheffé multiple comparison test showed that FFA values in groups 3 and 4 were significantly higher than those in groups 1 and 2 (p <0.001 for group 4 vs. 1 and 2, and 3 vs. 1; p<0.04 for group 3 vs. 2) Serum FFA and albumin levels were positively associated (r = 0.489, p <0.01). Using linear regression analysis, it was estimated that serum albumin values increased by 0.28 g/L per year (i.e. 0.5%) and FFA by 0.02 mmol/L (i.e. 3.8%). Thus, measured by standard methods, serum FFA and albumin could increase in response to several years of storage at -25 degrees C. It is suggested that the storage time dependent increase in FFA is due to FFA liberation from lipoprotein triglycerides, whereas the apparent increase in albumin concentration possibly could be attributed to an unfolding of the protein, allowing more bromcresol green to be bound.

Cancer in siblings of children with cancer in the Nordic countries: a population-based cohort study

BACKGROUND

In some rare inherited disorders such as Li-Fraumeni syndrome, relatives of children with cancer are at increased risk of cancer. We aimed to assess relations between childhood cancer and sibling risk, and evaluate the influence of recessive conditions in cancer causation.

METHODS

We did a population-based cohort study in the Nordic countries of 42277 siblings of 25605 children with cancer. Children with cancer were identified from records in the five Nordic cancer registries, and their siblings from nationwide population registries. Cancers in siblings were documented through record linkage with cancer registries and compared with national incidence rates. We also assessed cancer incidence in parents to identify familial cancer syndromes.

FINDINGS

284.2 cancers were expected in siblings, whereas 353 were diagnosed (standardised incidence ratio 1.24 95% CI 1.12-1.38). Risk ratios for siblings were highest in the first decade of life (2.59, 1.89-3.46). We excluded 56 families with genetic syndromes linked to cancer, which reduced this ratio from 1.7 to 1.0 (0.7-1.3) for siblings younger than 20 years, and from 1.3 to 1.0 (0.8-1.3) for those aged 20-29 years. We found no new patterns of familial cancer that indicated inherited susceptibility, or evidence that recessive conditions might contribute to cancers not explained by syndromes. 40% of cancers in siblings that occurred before age 20 years could be attributed to known genetic factors, whereas 60% remained unexplained.

INTERPRETATION

Apart from rare cancer syndromes, paediatric cancer is not an indicator of increased cancer risk in siblings.

Decreasing late mortality among five-year survivors of cancer in childhood and adolescence: a population-based study in the Nordic countries

PURPOSE

To assess the risk of death in patients who survive more than 5 years after diagnosis of childhood cancer and to evaluate causes of death in fatal cases.

PATIENTS AND METHODS

This was a population-based study in the five Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) using data of the nationwide cancer registries and the cause-of-death registries. The study cohort included 13,711 patients who were diagnosed with cancer before the age of 20 years between 1960 and 1989 and who survived at least 5 years from diagnosis. By December 31, 1995, 1,422 patients had died, and death certificates were assessed in 1,402. Standardized mortality ratios (SMRs) for validated causes of death were calculated based on 156,046 patient-years at risk.

RESULTS

The overall SMR was 10.8 (95% confidence interval [CI], 10.3 to 11.5), mainly due to high excess mortality from the primary cancer. SMR for second cancer was 4.9 (95% CI, 3.9 to 5.9) and was 3.1 (95% CI, 2.8 to 3.5) for noncancer death. The pattern of causes of death varied markedly between different groups of primary cancer diagnoses and was highly dependent on time passed since diagnosis. Overall late mortality was significantly lower in patients treated during the most recent period of time, 1980 to 1989, compared with those treated from 1960 to 1979 (hazard ratio, 0.61; 95% CI, 0.54 to 0.70), and there was no increase in rates of death due to cancer treatment.

CONCLUSION

Long-term survivors of childhood cancer had an increased mortality rate, mainly dying from primary cancers. However, modern treatments have reduced late cancer mortality without increasing the rate of therapy-related deaths.

A pooled analysis of case-control studies of thyroid cancer. VI. Fish and shellfish consumption

OBJECTIVE

To better understand the role of fish and shellfish on thyroid cancer risk, we systematically re-analyzed the original data from 13 case-control studies conducted in the US, Japan, China, and Europe.

METHODS

A total of 2497 cases (2023 women, 474 men) and 4337 controls (3268 women, 1069 men) were considered. Odds ratio (OR) and corresponding 95% confidence interval (CI) were estimated for each study by logistic regression models, conditioned on age and sex, and adjusted for history of goiter, thyroid nodules or adenomas, and radiation. Combined ORs were computed as the weighted average of the estimates from each study.

RESULTS

The ORs for the highest level of total fish consumption (three or more times per week) as compared to the lowest one (less than once per week) was above unity in Hawaii, Connecticut, Japan, Norway, Tromsø, and Vaud. Conversely, the ORs for the studies in Los Angeles. Shanghai, southeastern Sweden, Uppsala, northern Sweden, northern Italy, and Athens were below one. The pattern of risk for salt water fish and shellfish was not substantially different from that of total fish. Fish was not associated with thyroid cancer risk in all studies combined (OR = 0.99, 95% CI 0.85-1.2 for moderate, and OR=0.88, 95% CI 0.71-1.1 for high total fish consumption), but there was a suggestion of a protective effect in endemic goiter areas (OR = 0.65, 95% CI 0.48-0.88).

CONCLUSION

This combined analysis indicates that relatively elevated fish consumption does not appreciably increase thyroid cancer risk, and may have a favorable influence in areas where iodine deficiency is, or was, common.

Human papillomavirus infection as a risk factor for squamous-cell carcinoma of the head and neck

BACKGROUND

Oncogenic human papillomaviruses (HPVs), especially HPV type 16 (HPV-16), cause anogenital epithelial cancers and are suspected of causing epithelial cancers of the head and neck.

METHODS

To examine the relation between head and neck cancers and HPVs, we performed a nested case-control study within a joint Nordic cohort in which serum samples were collected from almost 900,000 subjects. Samples collected at enrollment from 292 persons in whom squamous-cell carcinoma of the head and neck developed, on average, 9.4 years after enrollment and from 1568 matched controls were analyzed for antibodies against HPV-16, HPV-18, HPV-33, and HPV-73 and for cotinine levels as a marker of smoking habits. Polymerase-chain-reaction (PCR) analyses for HPV DNA were performed in tumor tissue from 160 of the study patients with cancer.

RESULTS

After adjustment for cotinine levels, the odds ratio for squamous-cell carcinoma of the head and neck in subjects who were seropositive for HPV-16 was 2.2 (95 percent confidence interval, 1.4 to 3.4). No increased risk was observed for other HPV types. Fifty percent of oropharyngeal and 14 percent of tongue cancers contained HPV-16 DNA, according to PCR analysis.

CONCLUSIONS

HPV-16 infection may be a risk factor for squamous-cell carcinoma of the head and neck.

Familial occurrence of nonmedullary thyroid cancer: a population-based study of 5673 first-degree relatives of thyroid cancer patients from Norway

The purpose of this study was to estimate the occurrence of familial nonmedullary thyroid cancer (FNMTC) in a large population-based study. Of the 5274 cases of thyroid cancer on record in the Norwegian Cancer Registry between 1960 and 1995, a total of 1025 patients could be identified with verified thyroid cancer, a unique personal identification number, and a link to at least one parent. For patients with nonmedullary carcinoma, 5457 first-degree relatives in 970 families were found, compared with 216 first-degree relatives in 37 families for the medullary cancers. A standardized incidence ratio (SIR) was calculated among the relatives based on rates from the Cancer Registry of Norway. A significantly increased risk of thyroid cancer was found among the 5457 relatives of nonmedullary index cases, both for males [SIR, 5.2; confidence interval (CI), 2.1-10.7; 7 cases] and females (SIR, 4.9; CI, 3.0-7.7; 19 cases). All of these 26 thyroid cancer cases were of the nonmedullary type. Furthermore, an increased risk was found among 4282 relatives of papillary index cases, for both males (SIR, 5.8; CI, 2.1-12.6; 6 cases) and females (SIR, 4.0; CI, 2.1-7.1; 12 cases). The 36 familial papillary thyroid cancer patients had an average age at diagnosis of 43 years. Genetic influence is probably only modest for the familial nonmedullary cases and clearly weaker than for the classic familial type of medullary thyroid cancer.

A pooled analysis of thyroid cancer studies. V. Anthropometric factors

OBJECTIVE

To assess the relation between anthropometric factors and thyroid cancer risk in a pooled analysis of individual data from 12 case-control studies conducted in the US, Japan, China and Europe.

METHODS

2056 female and 417 male cases, 3358 female and 965 male controls were considered. Odds ratios (OR) were derived from logistic regression, conditioning on age, A-bomb exposure (Japan) and study, and adjusting for radiotherapy.

RESULTS

Compared to the lowest tertile of height, the pooled OR was 1.2 for females for the highest one, and 1.5 for males, and trends in risk were significant. With reference to weight at diagnosis, the OR for females was 1.2 for the highest tertile, and the trend in risk was significant, whereas no association was observed in males. Body mass index (BMI) at diagnosis was directly related to thyroid cancer risk in females (OR = 1.2 for the highest tertile), but not in males. No consistent pattern of risk emerged with BMI during the late teens. Most of the associations were observed both for papillary and follicular cancers, and in all age groups. However, significant heterogeneity was observed across studies.

CONCLUSIONS

Height and weight at diagnosis are moderately related to thyroid cancer risk.

Reproduction management of tethered cows on Norwegian dairy farms

Dairy farms in southern Norway were surveyed to obtain information regarding reproduction management in tied herds. A total of 1613 farms were included in the analyses. Reproductive performance during the main breeding period of the year (November 1 to February 28) was measured using the following dependent variables: calving to first service and last service interval, number of artificial inseminations per cow, non-return rate at 60 days, and calving interval. Culling for failure to conceive was found to be associated with longer calving to first service interval, more inseminations per cow and lower non-return rate. More inseminations per cow and lower non-return rate were also recorded in herds where breeding was close to calving. Oestrous checks late in the evening and frequent observations were associated with shorter calving to last service interval and shorter calving interval. Calving to last service interval was prolonged if the farmers were occupied with routine work while conducting oestrous checks. Manual rectal pregnancy testing was of little importance for reproductive efficiency in dairy herds with good breeding performance. More inseminations per cow occurred in herds where oestrous checks were conducted systematically 3 and 6 weeks after service. Calving to last service interval and calving interval were shorter when only one person was responsible for the herd breeding management.

A pooled analysis of case-control studies of thyroid cancer. IV. Benign thyroid diseases

OBJECTIVE

To obtain more precise estimates of the association between thyroid cancer and benign thyroid diseases and to elucidate the role of potential confounders or effect modifiers.

METHODS

The original data from 12 case-control studies from the United States, Asia, and Europe were pooled. Based on 2,094 women and 425 men with cancer of the thyroid and, respectively, 3,248 and 928 control subjects, odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were obtained by conditional regression models, conditioning on study and age at diagnosis, and adjusting for age and radiotherapy.

RESULTS

A history of hypothyroidism was not associated with cancer risk (pooled ORs = 0.9, 95% confidence interval, CI: 0.7-1.3 in women and 1.7, 95% CI: 0.3-11.7 in men). ORs for hyperthyroidism were 1.4 (95% CI: 1.0-2.1) in women and 3.1 (95% CI: 1.0-9.8) in men. In women, however, risk was lower in the absence of or after allowance for history of goiter. Pooled ORs for a history of goiter were 5.9 (95% CI: 4.2-8.1) in women and 38.3 (95% CI: 5.0-291.2) in men. Risk for a history of benign nodules/adenomas was especially high (OR = 29.9, 95% CI: 14.5-62.0, in women; 18 cases versus 0 controls in men). The excess risk for goiter and benign nodules/adenomas was greatest within 2-4 years prior to thyroid cancer diagnosis, but an elevated OR was present 10 years or more before cancer.

CONCLUSIONS

Goiter and benign nodules/adenomas are the strongest risk factors for thyroid cancer, apart from radiation in childhood.

Familial risk in head and neck squamous cell carcinoma diagnosed before the age of 45: a population-based study

This population-based study analyses familial risk as a factor in the development of head and neck squamous cell carcinoma before the age of 45. Two different designs were used: (1) estimation of standardised incidence ratios (SIRs) for cancer among first-degree relatives of 127 young head and neck cancer probands; and (2) estimation of odds ratios (ORs) for developing head and neck cancer associated with cancer in a first-degree relative. SIRs of cancer of the respiratory and upper digestive tract (lungs, oesophagus, and smoking-related head and neck sites [RUDT]) for first-degree relatives were 4.3 (95% confidence intervals or 95% CI of 1.6-9.5) for female patients, 1.0 (95% CI = 0.3-2.6) for male patients and 1.9 (95% CI = 0.9-3.5) for both sexes combined. ORs for head and neck cancer before the age of 45, in association with cancer of RUDT in a first-degree relative were 5.0 (95% CI = 1.4-17.3) for women, 1.1 (95% CI = 0.3-3.3) for men, and 2.0 (95% CI = 0.9-4.4) for both sexes combined. Hence, when analysing both sexes combined, our familial risk estimates for head and neck cancer showed non-significant increases. An explanation for the unexpected sex asymmetry in familial risk could be an interaction between inherent cancer susceptibility and a female biological characteristic. Alternatively, it could be artefacts caused by differences in familial smoking habits.

A pooled analysis of case-control studies of thyroid cancer. II. Menstrual and reproductive factors

OBJECTIVE

It has been suggested that female hormones, and hence menstrual and reproductive factors, play a role in thyroid cancer etiology. Epidemiological data, however, are limited and inconsistent, partly because of the small number of cases included in each study. To clarify the etiology of thyroid cancer, we conducted a pooled analysis of original data from 14 case-control studies, 4 from the United States, 2 from Asia, and 8 from Europe.

METHODS

This analysis included a total of 2,247 female cases of thyroid cancer (80% papillary) and 3,699 control women. Pooled odds ratios (OR) were estimated using logistic regression, conditioning on study and (i) matching sets for individually matched studies, or (ii) quinquennia of age for the other studies. Additional terms for age and history of radiation exposure were included in the regression equations.

RESULTS

The OR per year of later menarche was 1.04 (95% confidence interval (CI) 1.0-1.1). Compared to premenopausal women, the OR was 1.3 for women with natural menopause, and 1.8 for those with artificial menopause, but the studies were heterogeneous and the association may be due, at least in part, to diagnostic or ascertainment bias. Parity, spontaneous or induced abortions and history of infertility were not associated with thyroid cancer risk. The OR was above unity in women reporting later age at first birth (OR = 1.1, 95% CI 1.0-1.3 for 5-year delay) and higher in the first years after a birth.

CONCLUSIONS

The associations of menstrual and reproductive factors with thyroid cancer risk were generally weak, but appeared stronger among women diagnosed with thyroid cancer at younger ages.

A pooled analysis of case-control studies of thyroid cancer. I. Methods

OBJECTIVE

Because the etiology of thyroid cancer is not well described, we conducted a pooled analysis of all published case-control studies, as well as two identified unpublished studies. This paper describes the major characteristics of the 14 studies included in the analysis, as well as the statistical methods employed. Four studies were conducted in the United States (1 each in Washington State, California, Connecticut and Hawaii), 8 in Europe (3 in Sweden, 2 in Norway, 1 in Switzerland, 1 in Italy and 1 in Greece), and 2 in Asia (1 in China and 1 in Japan).

METHODS

The original datasets were obtained and restructured in a uniform format. Data on socio-demographic characteristics, anthropometric measures, smoking and alcohol consumption, history of benign thyroid diseases and of other selected medical conditions and treatments, family history of cancer and of benign thyroid conditions, occupation, residence in endemic goitre areas, and dietary habits were analyzed. For women, we also analyzed menstrual and reproductive factors and use of female hormones. Radiotherapy and, in Japan, exposure to the A-bombs were considered as potential confounding factors.

RESULTS

A total of 2,725 cases (2,247 females and 478 males) and 4,776 controls (3,699 females and 1,077 males) were included in this study. Of the cases, 79% were classified as papillary thyroid carcinomas, 14% as follicular, 2% medullary, 1% anaplastic, 1% other histologies, and 3% histological type unknown. Each of the datasets was checked for outliers and consistency. Data were analysed separately by study center, gender, and the two major histologic types (papillary, follicular). Frequency tables and simple statistics were computed for each variable under study. Conditional logistic regression was used to compute odds ratios. For matched studies, the original matching was preserved, whereas, for unmatched ones, five-year age groups were used for matching. Study-specific analyses were computed, and then the data from all the studies were pooled conditioning on study. Heterogeneity between studies, geographic areas and study designs was assessed, and the modifying effect of age was also evaluated.

Serum dehydroepiandrosterone sulfate concentration and thyroid cancer risk: a matched case control study

In animal models of carcinogenesis, pharmacological doses of dehydroepiandrosterone (DHEA) treatment appear to reduce the incidence of chemically induced thyroid cancers. DHEA and its sulfate (DHEA-S) are secreted in approximately equal amounts, but serum levels of DHEA-S are 300-500 times higher and have no diurnal variation when compared to DHEA. The hypothesis that serum concentrations of DHEA-S may be associated with thyroid cancer risk was tested in a population-based prospective case control study. Data from the practically complete nationwide Cancer Registry of Norway were linked to the data file of a serum bank comprising blood samples from 300,000 Norwegian men and women obtained through national health surveys. A total of 113 donors, who during the years after blood sampling received a diagnosis of thyroid cancer, were identified in the serum bank and were eligible for the study. Each case was matched with 3 controls. Serum levels of DHEA-S were determined blindly. Controls were divided into tertiles, and odds ratios between cases and controls were determined relative to the group with the lowest serum DHEA-S level. The risk of developing thyroid cancer was determined in women 50 years of age or older, in women below age 50, in men, and in the subgroup of 77 cases who had morphologically verified papillary thyroid cancer. No significant association between prediagnostic serum DHEA-S concentrations and thyroid cancer risk was observed. These data indicate that DHEA-S within physiological concentrations does not reduce the risk of thyroid cancer.

[Increased incidence of thyroid cancer among Norwegian women married to fishermen]

The relationship between thyroid cancer in women and the occupation of their spouses was examined in a retrospective cohort study. Of the 2.9 million women registered in the Central Population Registry of Norway by the end of 1991, 1.2 million had a spouse registered with an occupation in one or more of the censuses of 1960, 1970 or 1980. These women were included in the study. Based on the first digit of their husbands' five-digit Nordic occupational code, the women were assigned to ten broad categories. A standardised incidence ratio (SIR) and 95% confidence interval were calculated for each occupational category. The women were further subdivided and analysed in 71 groups defined by the first two digits of their husband's occupational code. Among the women included in the study, a total of 2,409 cases of thyroid cancer were reported to the Cancer Registry of Norway during the period 1960-92. A significantly elevated risk of thyroid cancer was found only among women whose spouses belonged to the occupational category Agriculture, forestry or fishery (n = 208,279), with a SIR of 1.13. In the subgroup Fishing, whaling and sealing work (n = 40,839), the risk was even higher with a standardised incidence ratio of 1.91. Our data support the proposed relationship between increased risk of thyroid cancer and mode of living, more specifically dietary fish or other seafood.

Risk of cancer among offspring of childhood-cancer survivors. Association of the Nordic Cancer Registries and the Nordic Society of Paediatric Haematology and Oncology

BACKGROUND

Increasing numbers of children with cancer survive and reach reproductive age. However, the risk of cancer (other than retinoblastoma) in the offspring of survivors of childhood and adolescent cancer is uncertain.

METHODS

Using data from national cancer and birth registries, we assessed the risk of cancer among 5847 offspring of 14,652 survivors of cancer in childhood or adolescence diagnosed since the 1940s and 1950s in Denmark, Finland, Iceland, Norway, and Sweden. The offspring were followed up for a diagnosis of cancer for 86,780 person-years, and standardized incidence ratios were calculated.

RESULTS

Among the 5847 offspring, 44 malignant neoplasms were diagnosed (standardized incidence ratio, 2.6; 95 percent confidence interval, 1.9 to 3.5). There were 17 retinoblastomas, yielding a standardized incidence ratio of 37. There were 27 neoplasms other than retinoblastoma (standardized incidence ratio, 1.6; 95 percent confidence interval, 1.1 to 2.4). The second most common primary site of cancer among the offspring was the brain and nervous system, in which eight tumors were observed (standardized incidence ratio, 2.0; 95 percent confidence interval, 0.9 to 3.9.) There were between zero and four apparently sporadic cases of cancer in other primary sites among the offspring. Excluding 4 likely cases of hereditary cancer and 2 subsequent cancers among the offspring with hereditary retinoblastoma, there were 22 sporadic cancers, for a standardized incidence ratio of 1.3 (95 percent confidence interval, 0.8 to 2.0).

CONCLUSIONS

There is no evidence of a significantly increased risk of nonhereditary cancer among the offspring of survivors of cancer in childhood.

Squamous cell carcinomas of the head and neck in Norway, 1953-92: an epidemiologic study of a low-risk population

Trends in incidence, five-year relative survival, and mortality among patients in Norway with squamous cell carcinoma of the oral sites, oro-/hypopharynx, and larynx were studied for the period 1953-92. Throughout the first part of the study period, age-adjusted incidence rates (AAIR) of oral cancer remained stable in both genders. Since the end of the 1960s, AAIRs increased by 13 percent per five-year period in males and 12 percent in females. The figures suggest increased male incidence rates of oral cancer in younger age groups. During the same period, AAIRs of cancers of the oro-/hypopharynx in males increased by 19 percent per five-year period. The AAIRs of laryngeal cancer increased steadily from 1953-92 among both males and females by 17 percent and 21 percent per five-year period, respectively. For all sites, changes in AAIRs for males were greater in rural than in urban areas. No improvement in detection of disease at a localized stage was observed for either gender. There are indications of improvements in the five-year relative survival rates for oral and pharyngeal cancer in both genders. For all sites, relative survival was better in younger than in older patients. Only in the case of pharyngeal cancer in males was an increase in disease-specific mortality rates positive for a time trend.

A population-based case-control study of canine mammary tumours and clinical use of medroxyprogesterone acetate

We investigated whether or not an association could be found between mammary tumours and prior clinical use of medroxyprogesterone acetate (MPA) in bitches. A population-based retrospective age-matched case-control study was designed based on interviews with the owners of the bitches. The proportion of bitches with diagnosed mammary tumours (group MT+, n = 98) that had received progestin injections was compared with the proportion in a control group without mammary tumours (group MT-, n = 98). In the case group 39%, and in the control group 21% of the bitches had been treated with MPA. A significantly higher number of bitches with mammary tumours had been exposed to progestins, compared with the control group without mammary tumours (odds ratio = 2.32, Chi-square = 7.01, p = 0.008). Bitches treated clinically with low doses of MPA to avoid oestrus were at a greater risk of developing mammary tumours, the majority of which were histologically malignant (91%).

Increased risk of thyroid cancer among Norwegian women married to fishery workers--a retrospective cohort study

The relationship between thyroid cancer in women and the occupation of their spouses was examined in a retrospective cohort study, with special reference to fishery. Of the 2.9 million women registered in the Central Population Registry of Norway on 31 December 1991, 1.2 million women had a spouse registered with an occupation in one or more of the censuses in 1960, 1970 or 1980. The women were assigned to ten broad categories based on the first digit of their husbands five-digit Nordic occupational classification code NYK, and a standardized incidence ratio (SIR) was calculated for each occupational category. The women were further subdivided and analysed in 71 groups defined by the first two digits of the NYK code. Among the women included in the study, a total of 2409 cases of thyroid cancer were reported to the cancer registry of Norway during 1960-92. A significantly elevated risk of thyroid cancer was found only among women whose spouses belonged to the occupational category 'agriculture, forestry or fishery' (n = 208 279), with a SIR of 1.13. In the group associated with 'fishing, whaling and sealing work' (n = 40 839), the risk was further increased (SIR 1.91, CI 1.65-2.21). An increased risk was also detected in the group associated with 'ship officers and pilots work' (n = 29 133) (SIR 1.35, CI 1.07-1.67). When allocating the women to southern and northern cohorts determined by their county of birth, a difference in risk was clearly present in all 10 occupational categories, with figures being 50-60% higher in the north. However, there was practically no difference in incidence between northern and southern cohorts among women associated with fishery work. Thus, the results obtained from this study indicate that being a fisherman's wife is associated with elevated risk of thyroid cancer, and our data support the suggested role of seafood as an aetiological factor.

Multiple sclerosis and cancer in Norway. A retrospective cohort study

INTRODUCTION

During the extended course of multiple sclerosis (MS) there are ample opportunities for the patients to develop other illnesses including cancer, a potential long-term complication of the immunosuppressive drug treatment in MS.

MATERIAL AND METHODS

A retrospective cohort study was done to estimate the relative risk of cancer in a population of MS-patients from three Norwegian counties by record linkage with the Cancer Registry of Norway. The cohort comprised 1271 MS-patients, 530 men and 741 women, identified in five longitudinal population-based incidence studies. The reporting of cancer cases has been compulsory in Norway since 1952.

RESULTS

We found 73 cancer cases (standardized incidence ratio (SIR) = 0.86, 95% CI 0.68-1.09). Mean follow-up time was 18.4 years. A significant excess of breast cancers was observed (SIR = 1.70, 95% CI 1.05-2.60). A non-significant excess of cancer in the urinary tract was observed. No significantly increased risk in hematologic and lymphatic malignancies or malignant brain tumors was observed. The incidence of cancer of the digestive organs was significantly lower than expected (SIR = 0.51, 95% CI 0.24-0.93).

CONCLUSION

Overall, the study indicates that an MS-patient is not at any unusual risk for subsequent development of cancer compared to the normal population.

Study of distribution and interaction of arsenic and selenium in rat thyroid

Seventy-eight Wistar weanling rats were pretreated with arsenate (100 mg/L As), selenite (1 mg/L Se), and arsenate (100 mg/L As) plus selenite (1 mg/L Se) added to the drinking water. After 4 w, all the animals were sacrificed and serum T3 and T4 were determined by double-antibody radioimmunoassay. Thyroid tissue concentrations of As and Se were determined in female rats by neutron activation analysis, and tissue specimens were examined histopathologically. For both sexes, the measurements indicated that T4/T3 was lowest in the Se group, intermediate in the As group, and highest in the controls. Corrected for the mean value of the controls, mean As concentration of thyroid tissue was of the same magnitude in the group pretreated with As + Se as the sum of the mean As concentration in the groups pretreated with As or Se alone. The outcome was symmetric with regard to the Se concentration: In the As + Se pretreated group, the mean Se concentration was of the same magnitude as the sum of the mean Se concentration in the groups pretreated with As or Se alone. Thus, As and Se tended to accumulate in the thyroid tissue. Postmortem examination showed that the thyroid tissue of rats pretreated with As alone exhibited obvious, toxic changes, whereas only minor or no changes were found in the tissues of the groups pretreated with Se or As + Se, and in the tissues of the controls. Multivariate analyses demonstrated that s-T4 and s-T3 were significantly correlated with sex, that s-T3 was positively correlated (p < or = 0.001) with Se pretreatment, and that the T4/T3 ratio was negatively correlated with both As (p < or = 0.012) and Se pretreatment (p < or = 0.001). The results were discussed in relation to the cancer preventive effect of Se.

Head and neck cancer in Norway. A study of the quality of the Cancer Registry of Norway's data on head and neck cancer for the period 1953-1991

Data from population-based cancer registries provide information on the causes and outcome of cancer and form a basis for important decision making in connection with the prevention of cancer and the planning of health services. This makes it of the utmost importance to assess the data at all stages of collection to ensure the highest possible quality. The present study focuses on the quality of the Cancer Registry of Norway's data on head and neck cancer for the period 1953-1991. When the study was started, 16,104 cases of head and neck malignancies had been registered. All histological codes were reviewed. The pathologists' reports were reevaluated for 369 cases selected according to set criteria: 133 cases received a new histological code without being excluded from the data material: 112 cases were excluded. The distribution of histological diagnoses for each location is presented. A reevaluation of 300 cases selected at random from the corrected series indicates discrepancies between the pathologist's classification and the Registry's coding in less than 2% (1.4%) of all cases. The percentage that lacked histological verification fell from 5.7% in the first decade to 2.1% during the last 9-year period. Completeness of the Cancer Registry's data base was checked against hospital-based registries and this investigation showed that virtually all new cases are reported. We conclude that the data on head and neck cancer for the studied time period meet standards that justify their use as a basis for epidemiological as well as clinical studies.

[Registration of canine cancer]

A Norwegian Canine Cancer Registry, covering four of 19 counties, has been operative since March 1990. Until the end of April 1994 about 6,000 tumours have been registered, more than 50% of these being manifestly or potentially malignant. Among 14 selected breeds the relative risk ratio for all tumours varies with factor 35 from boxer to dunker, the boxer having the highest tumour risk. The percentage distribution of specified tumour types also varies greatly between breeds, mammary cancer constituting 59% of all neoplasms in the dachshund, but only 4% in the Bernese mountain dog. Because of the genetic diversity between breeds the dog is a suitable species for differentiation between genetically determined predisposition and environmental influences in the etiology of cancer. Epidemiological surveillance of cancer morbidity in dogs may be a useful instrument for tracing carcinogens, even in the surroundings of man.

Longchain serum fatty acids and risk of thyroid cancer: a population-based case-control study in Norway

Epidemiologic studies have shown an association between seafood consumption and risk of thyroid cancer. Fish meals increase the serum concentrations of the longchain fatty acids, eicosapentaenoic acid (20:5,n-3) (EPA) and docosahexaenoic acid (22:6,n-3) (DHA), for days. The hypothesis that serum concentrations of fatty acids may be associated with thyroid cancer risk therefore was tested in a population-based case-control study with 74 cases and 221 matched controls. Seventy-three cases with sera in the Norwegian serum bank (JANUS) were identified in the Norwegian Cancer Registry and matched with three controls, also in JANUS, on age, gender, place of residence, and time of blood sampling. One [corrected] case was matched with two controls. Serum concentrations of 11 longchain fatty acids were determined blindly by gas chromatography for all subjects. Controls were divided into three groups with increasing serum fatty acid concentrations, and odds ratios between cases and controls were estimated relative to the group with lowest serum level by univariate and multivariate analyses. The main finding was a significant inverse relation between the sum of arachidonic acid (20:4,n-6) (AA) and DHA serum concentrations and thyroid cancer risk. The significance of this association was weakened when the analyses were restricted to the papillary type of thyroid carcinoma. It was of the same order of magnitude whether the period between blood sampling and diagnosis was greater than eight years, or eight or less years. High EPA/AA ratio, indicating consumption of fish fat, was not associated significantly with increased thyroid-cancer risk.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence of cancer among lighthouse keepers exposed to asbestos in drinking water

The study population comprises 690 Norwegian male lighthouse keepers whose water supply came from cisterns that received rain water off asbestos-cement-tiled roofs. The asbestos-cement tiles were installed in the late 1950s, and two decades later the fiber content in the tap water was analyzed. The fiber content ranged from 1,760 to 71,350 million fibers per liter, which is significantly higher than measured in any other Norwegian public water supply. During the follow-up period, 1960-1991, no statistically significant excess risk was found for any type of cancer in the group with a latency period of 20 years or more, except for stomach cancer (11 observed cases vs. 4.57 expected, standardized incidence ratio = 241, 95% confidence interval 120-431). No cases of malignant mesothelioma were found. The study is limited by lack of knowledge as to when the tiles began to deteriorate and, thus, the magnitude of total exposure as well as by the inability to control for such potential confounding factors as diet.

[Bone mineral density and occurrence of fractures in 66-year old women in Oslo]

During 1991 we examined 196 randomly chosen females born in 1925 and resident in Oslo. 40% had suffered fractures of the appendicular skeleton, most commonly of the forearm and the ankles, after the menopause. Results from bone mineral density measurements of the lumbar spine (L2-4) and the femoral neck were not significantly lower, while results from the distal 1/3 of the forearm site were significantly lower, among participants with fractures than among participants without fractures. The values for bone mineral density obtained from these three sites corresponded with the values reported from other countries. Biochemical indices of calcium metabolism were similar in fracture and non-fracture subjects. Age at menopause, weight, height and demographic characteristics were also similar in the two groups. We conclude that low bone mineral density cannot be the sole explanation of the very high prevalence of fractures among female residents of Oslo found in the present and previous studies.

Incidence pattern of thyroid cancer in Norway: influence of birth cohort and time period

The incidence of thyroid cancer in Norway increased about 2-fold for both sexes during the period 1955 to 1989 (4691 cases). In the last 5-year period, however, a decline was observed, especially among females. The ratio between age-adjusted incidence rates in Northern Norway compared with Southern Norway was 1.6 for females and 1.5 for males, and the incidence pattern during the period was similar in the 2 regions. The analysis of age-cohort-period models showed a strong cohort effect in both sexes. The reason for this is not clear, although radiation treatment during childhood and dietary habits may possibly be involved. A weaker but statistically significant and transient period effect was also present, giving relatively higher incidence rates, especially in the 1970s. Although this result may be consistent with an influence of radioactive fallout in the northern area, more detailed studies are needed.

A sub-site-specific analysis of the relationship between colorectal cancer and parity in complete male and female Norwegian birth cohorts

Register and census data for complete cohorts of Norwegian men and women born between 1935 and 1969 have been used to examine the relationship between reproductive factors and the incidence of colorectal cancer. Among 1.1 million men and 1.1 million women under observation, 491 male and 859 female cases of colorectal cancer were diagnosed during the period of follow-up. Our hazard model estimates clearly show that in these young cohorts, women with 2 or more children run a lower risk of having a malignant tumor in the cecum or ascending colon than do other women of the same age and in the same birth cohort. No association with parity is found with respect to cancer in the transverse or descending colon, whereas a downward trend in the effect estimates, followed by an upturn, appears for the rectum, sigmoid colon and rectosigmoid junction. Such correlations, which also hold when we control for education and place of residence, are not found for men. The observed relationship between parity and cancer incidence is not likely to be exclusively explained by life-style differentials. Presumably, there is a biological effect of the number of pregnancies and deliveries, net of age at first birth and other reproductive factors, on the development of colorectal cancer.

Thyroid cancer in children in Norway 1953-1987

All cases of thyroid cancer in children aged 15 years or younger registered in Norway (1953-1987) are presented. 30 girls and 5 boys are included, the youngest being a 6-year-old boy. Half of the patients were in the age-group 14-15 years. As for adults, papillary thyroid cancer was most common. 70% of the patients presented with tumour growth outside the thyroid gland. In spite of this, only 2 children died of the disease during the follow-time (maximum 37 years).

Norwegian case-control study testing the hypothesis that seafood increases the risk of thyroid cancer

The hypothesis that consumption of seafood increases the risk of thyroid cancer has been tested by means of a matched case-control study. Linking the file of the National Health Screening Service (NHSS) containing dietary information about 60,000 Norwegians with the 1955-89 thyroid-cancer file of the Cancer Registry, by means of the 11-digit person-number, resulted in 92 cases--each of whom was matched with five controls with regard to age, gender, and place of residence. Forty-eight cases had answered questions on diet before diagnosis; 44 did so after diagnosis. Exposure data on seafood and seafood-related vitamins were recovered from the NHSS files for all 552 subjects. Odds ratios (OR) were computed by means of conditional logistic regression analysis. Univariate analysis of the 48 sets in which the case had answered the dietary questionnaire prior to the thyroid cancer diagnosis, as well as of all 92 sets, indicate that regular users of cod-liver oil, fish liver, or fish sandwich-spread run a higher risk of thyroid cancer than irregular and nonusers, and people eating more fish dinners per week also run a higher risk of thyroid cancer. Stepwise regression analysis corroborates the study hypothesis by showing that these two seafood variables increase the risk of thyroid cancer significantly. On the other hand, the results of a simultaneous regression analysis of these two seafood variables and a dietary vitamin-D index-variable tend to reduce the tenability of the above-mentioned conclusion since none of the OR estimates (all greater than one) reached significance in this part of the statistical analysis.

Second malignancies in thyroid cancer patients: a population-based survey of 3658 cases from Norway

In a population-based survey of 3658 thyroid cancer patients diagnosed in Norway during 1955-85, a total of 200 cases of second malignancies were observed (30,414 person-years, mean follow-up 8.4 years). Male patients had a significantly increased incidence of urogenital cancer [standardised incidence ratio (SIR) = 1.96, 95% confidence interval (CI) 1.4-2.7], including cancer of the testis (SIR = 11.8, 95% CI 3.2-30.1) and urinary bladder (SIR = 3.0, 95% CI 1.5-5.2). The occurrence of malignant melanoma was also increased among males (SIR = 4.2, 95% CI 1.4-9.7). This apparent association with urogenital cancers among males at the present time cannot be explained, although increased surveillance as well as specific aetiological factors should be considered.

Positive correlation between parity and incidence of thyroid cancer: new evidence based on complete Norwegian birth cohorts

We have examined the effect of parity on the incidence of thyroid cancer within a hazard model framework, using individual data on all (1.1 million) Norwegian women born 1935-1969. This unique data source was established by linking information from the Cancer Registry with maternity histories derived from the Central Population Register of Norway. The relative effects on the total incidence of thyroid cancer, net of age, place of residence and birth cohort, are 1.00 for the childless (arbitrarily chosen baseline group), 1.13 for parity 1, 1.30 for parity 2, 1.39 for parity 3 and 1.46 for parity 4+. The latter 3 figures are significantly higher than 1.00. The effects are larger for follicular carcinoma, and for this type of thyroid cancer there are also indications of a recent-pregnancy effect. Among women with 2 or more children, those who became pregnant less than 45 months previously have a higher cancer incidence than others at the same parity. Moreover, we have found that parity has virtually the same effect at all ages, in all birth cohorts and in both parts of the country. Age at first birth as well as the length of the interbirth interval appear to be unrelated to the thyroid-cancer risk. Our findings are consistent with previous case-control studies from other countries.

Mortality from dementia among gastroduodenal ulcer patients

STUDY OBJECTIVE

The aim was to examine whether a high intake of aluminium containing antacids is a risk for Alzheimer's disease.

DESIGN

The mortality from dementia (1970-87), coded from death certificates as underlying or contributory cause of death, was compared with national rates in a cohort of patients who had surgery for gastroduodenal ulcer disease between 1911 and 1978.

SETTING

Patient data were obtained from patient records from major hospitals in western Norway.

PARTICIPANTS

4179 patients were identified who met the study criteria, which included having had a documented stomach operation, having a reliably identifiable personal number, and being alive on Jan 1, 1970.

MEASUREMENTS AND MAIN RESULTS

The standardised mortality ratio for dementia was 1.10 (95% CI 0.85-1.40, n = 64) for all patients, while for patients operated on in the period 1967-78 it was 1.25 (95% CI 0.66-2.13, n = 13).

CONCLUSIONS

As the majority of patients operated on after 1963 have probably been heavy consumers of aluminium containing antacids, the study provides meager evidence that a high intake of aluminium is an important risk factor for Alzheimer's disease, the major cause of dementia. However, the possibility of a raised mortality from Alzheimer's disease cannot be ruled out due to probable misclassification both in diagnosis and exposure. In addition, the observation period may have been too short to detect an effect since the latent period for Alzheimer's disease may be very long.

Survival and causes of death in thyroid cancer: a population-based study of 2479 cases from Norway

Survival and prognostic factors were studied in 2479 clinically presenting thyroid cancers (TC) reported from the entire Norwegian population from 1970 to 1985. Complete follow-up was obtained (median, 48 months), with information on causes of death. At the end of the observation period, 498 patients were reported to have died of TC, representing 69.7% of all deaths. Among 216 patients dying of other main causes, TC was considered to be a contributing cause of death in 80 cases (11.2%). Multivariate regression analysis of TC deaths showed no significant difference according to sex in any of the histological types. Age had a strong impact on survival, and for papillary carcinomas this effect was apparent after the age of 55 years. Marked differences were observed between various histological types, even between papillary and follicular carcinomas when interactions were included. Furthermore, tumor stage was a strong predictor of TC deaths, and a reduced survival was also found in patients with lymph node metastases. In conclusion, the importance of age, histological type, and tumor stage as major prognostic factors has been documented in this population-based study from Norway.

Incidence of thyroid cancer in Norway 1970-1985. Population review on time trend, sex, age, histological type and tumour stage in 2625 cases

In the Norwegian population, a total of 1977 females and 648 males had a diagnosis of thyroid cancer and were reported to the Cancer Registry during 1970-85. Most of the cases (98%) were histologically or cytologically confirmed, and 141 cases were diagnosed at autopsy (5.4%). Of the patients with information available, 13% had not been subjected to radical surgery. The actual number and annual incidence rate of thyroid cancer increased during the period, especially among females, although a possible levelling off was observed at the end. The frequency of papillary carcinoma clearly increased with time, and tumours were more often localized at presentation in later years. Improved detection of smaller tumours and differences in histopathological judgement may in part explain these results, but our findings are so notable that etiological factors must also be accounted for and researched. Associations between sex, age, histology and stage were further studied in a multivariate log-linear model. The results confirm the importance of sex and age when exploring the observed incidence pattern and also show that various histological types are unique with respect to metastatic patterns, when confounding factors have been adjusted for.

[Coding of diagnoses according to ICD-9]

The paper gives an account of the principal structure and main characteristics of the International Classification of Diseases, 1975 Revision (ICD-9), which has been used by Norwegian hospitals and the Norwegian public health administration since 1987. ICD-9 coding rules are examined, mainly the basic rule that transformation of diagnoses to codes should be complete, or should result in the smallest possible loss of information and convey no invented information. The rule of multiple coding states that, if possible, diagnoses which can be coded only with much loss of information should be divided into smaller entities. The ICD-9 code of the diagnosis comprises the codes of the set of entities which most reduces loss of information. If more than one set of entities represents the same amount of reduction in loss of information, then the set with the smallest number of entities should be chosen for reasons of reproducibility. The paper also presents the two procedures by which the corresponding ICD-9 category and code for a given diagnosis can be searched and identified.

[Use of ICD-9 in Norwegian hospitals. A questionnaire]

In 1988 a questionnaire was sent to every Norwegian clinical department to obtain a nationwide overview of the current use of the International Classification of Diseases (ICD-9), as recommended by the Director General of Health. The departments were asked about coding and registration routines, follow-up and control, and if they provided training in using the ICD-9. Questions were also asked concerning the advantage of the classification, any difficulties encountered, and if abbreviated code lists had been made for everyday use. Other comments were also welcomed. The main results of the study show that the majority of clinical hospital departments now use ICD-9. About 65% of the departments who took part in the study find it a useful tool, but there is no marked general enthusiasm.

Selenium concentrations in the human thyroid gland

Recently, we found that prediagnostic serum selenium concentration was significantly lower for cases developing thyroid cancer (n = 43) than for controls. We assumed that redistribution of serum selenium into the affected tissue took place in the prediagnostic period. The present study was carried out to determine the physiological concentration of selenium in the thyroid, since very few data are available in the literature. The concentrations of selenium in the thyroid (n = 45) and liver samples from Norwegians who had died because of acute illness or accidents were determined by hydride generation atomic absorption spectrometry. The mean selenium concentration was found to be 0.72 +/- 0.44 microgram/g in the thyroid and 0.45 +/- 0.11 microgram/g in the liver tissue. The surprisingly high concentration of selenium in apparently normal thyroids indicates that selenium has important functions in this organ. The remarkably broad range, together with the observation that no significant correlation exists between thyroid and liver concentrations, suggest that factors other than the selenium status are important determinants for the selenium concentration in the thyroid gland. This observation is consistent with our hypothesis that in carcinogenesis, prediagnostic processes influence the serum-/thyroid-ratio of selenium.

The WHO principles for registering causes of death: suggestions for improvement

In the ongoing 10th revision of the International Classification of Diseases, the WHO's rules for registering causes of death are revised. Previous studies have shown that deficiencies in the WHO's rules and basic concepts for registering causes of death impair the quality of cause-of-death statistics. The purpose of the present paper is to elucidate some of these shortcomings and to make suggestions for improvement. Also, the purpose of the WHO's definition of 'the underlying cause of death' is discussed, and a modification suggested. Suggestions are also made for new definitions of the four basic WHO concepts, 'causes of death', 'the underlying cause of death', 'direct cause' and 'contributory conditions'. At the end an account is given of the proposals made within the WHO for changes in the rules for registering causes of death.

Neoplasms of the central nervous system in Norway. V. Meningioma and cancer of other sites. An analysis of the occurrence of multiple primary neoplasms in meningioma patients in Norway from 1955 through 1986

The association between meningioma and a primary malignant neoplasm at another site was studied. The data from the population-based Norwegian Cancer Registry were analysed according to whether the meningioma occurred before or after the malignant neoplasm. Male patients with meningioma showed a raised risk for developing a subsequent renal cancer. A significant association was found between meningioma and subsequent breast cancer in females 50-64 years old at time of meningioma diagnosis and between breast cancer and subsequent occurrence of meningioma. Breast cancer patients with symptoms of an intracranial neoplasm may therefore have a potentially curable meningioma and female meningioma patients over 50 years should be considered for breast cancer screening programmes.

[Mortality of patients with differentiated thyroid carcinoma in Norway. The influence of sex, age, tumor stage, histologic type and residence at the time of diagnosis]

A multivariate analysis of relative survival and prognostic factors in differentiated thyroid cancer, based on all 2,625 cases reported to the Cancer Registry of Norway 1970-85, showed that age and tumour stage had a strong and individual impact on survival, while sex and histology had only a minor influence. The incidence of thyroid cancer has previously been shown to differ between different geographical locations and types of community in Norway, being highest in Northern Norway and in fishing communities, compared with southern parts and agricultural and industrial communities. These residence-related features had no influence on survival, implying that prognosis may depend on other factors than place of residence.

Prediagnostic serum selenium in a case-control study of thyroid cancer

Sera from 43 persons who developed thyroid cancer on an average 4.8 years after blood sampling were compared with sera from controls. Three controls per case matched for sex, age, place of residence and year of blood sampling, with regard to serum selenium and serum copper. Cases were significantly lower in serum selenium than controls, and the estimated odds ratio of thyroid cancer increased from 1 for levels greater than or equal to 1.65 mumol/l, to 6.1 for levels 1.26-1.64 mumol/l, to 7.7 for levels less than or equal to 1.25 mumol/l. When time from blood sampling to diagnosis of the case was considered, it could be shown that the protective effect of high serum selenium concentrations was restricted to the last (less than 7) years prior to the diagnosis of thyroid cancer. The serum selenium concentration of cases tended to decrease relative to controls the shorter time was from blood sampling to the diagnosis. There was no difference between cases and controls with regard to serum copper.

Survival and prognostic factors in differentiated thyroid cancer--a multivariate analysis of 1,055 cases

Survival (5- and 10-year) and prognostic factors of all differentiated thyroid cancer patients (n = 1,055) occurring in Norway in 1970-79 are presented. The multivariate analysis (GLIM) revealed that stage and age were the only significant prognostic factors. Sex and histological type could not be proved to be of major prognostic value. The decline in relative survival with age was different in the three stages, appearing as a continuous decrease in stage 3, while in stage 1 the decrease was present only in patients older than 75 years.