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.

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.

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.

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. 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.

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.

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.

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.

[Increased incidence of thyroid cancer among Norwegian women married to fishermen]. / Okt forekomst av kreft i skjoldkjertelen blant norske kvinner gift med fiskere.

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%).