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Objectives: To compare the risk of cancer between BRCA1 or BRCA2 mutation-positive and -negative families.Methods: We assessed standardized incidence ratios (SIR) in 107 Finnish breast cancer families (12 BRCA1, 11 BRCA2, 84 non-BRCA1/2) with confirmed genealogy. The observed numbers of cancer cases were compared to the expected ones; both numbers were based on the population-based Finnish Cancer Registry.Results: Risk of ovarian cancer for first-degree relatives was high in BRCA1 (SIR 29, 95% confidence interval 9.4-68) and in BRCA2 families (SIR 18. 8.3-35), but not increased for non-BRCA1/2 families (SIR 1.0, 0.2-2.9). The SIR for subsequent ovarian cancer among breast cancer patients was 61 (20-142), 38 (11-98), and 0 (0-4.2), respectively. The risk of subsequent new breast cancer among breast cancer patients was equally high in BRCA1 families (SIR 11, 3.6-26) and in BRCA2 families (SIR 10, 3.3-24) and somewhat lower in mutation-negative families (SIR 3.7, 2.1-6.1). The risk of breast cancer among relatives was markedly increased in all three groups. The only elevated SIR, besides breast and ovarian, was that for prostate cancer in BRCA2 families (SIR 4.9, 1.8-11).Conclusions: The excess risk of breast cancer in non-BRCA1/2 families suggests the existence of another predisposition gene which seems not to be linked with increased risk of ovarian cancer. [ABSTRACT FROM AUTHOR]

Objectives: The significance of reproductive factors on breast cancer risk has so far been characterized in populations with 5-paras as the highest category of parity. We extended these studies to a nationwide cohort of women with at least five births (grand multiparas = GM) by assessing the significance of parity, age at first birth, and average birth interval to the risk of breast cancer.Methods: The study cohort obtained from the Population Register of Finland comprised 86,978 GM-women; the incidence of cancer cases was obtained from the populated-based Finnish Cancer Registry. During a follow-up of about 2 million person-years, 1508 breast cancers were obtained. Standardized incidence ratios (SIRs) were calculated by dividing the number of observed cases by the number expected on the basis of national rates.Results: In the GM cohort the incidence of breast cancer was low (SIR 0.55, 95% confidence interval 0.52-0.58). The relative risk decreased significantly from 5-paras (SIR 0.60, adjusted for the other study variables) to 8-paras (SIR 0.40). The increase in the age at first birth from less than 20 years to 30+ years nearly doubled the risk (SIR from 0.40 to 0.73). Parity was a significant risk determinant only in ductal cancer, while shortening the birth interval was protective only in lobular cancer. The incidence of advanced breast cancer among GM-women exceeded the population rate in premenopausal women and in women with first birth at the age of 30 years or more.Conclusions: Our study demonstrated that young age at first birth and increasing number of births were independent and powerful protective factors from the fifth child onwards, while birth interval was weak in this respect. The tumor morphology and the clinical advancement of malignancy modified the dependence of breast cancer risk on reproductive variables. [ABSTRACT FROM AUTHOR]

Objective: Five to ten percent of prostate cancers may be caused by inherited genetic defects. In order to explore the nature of inherited cancer risks in the genetically homogeneous Finnish population, we investigated the incidence of prostate cancer and other cancers in first-degree relatives of prostate cancer patients by linking the population-based parish records on relatives with the Finnish Cancer Registry (FCR) data.Methods: The study population was composed of first-degree relatives of two groups of prostate cancer patients diagnosed in Finland during 1988-1993: (1) all early-onset (<60 years) patients (n = 557) from the entire country, (2) a sample (n = 989) of prostate cancer patients diagnosed at an age of > 60 years. A total of 11,427 first-degree relatives were identified through parish records, and their cancer incidence was determined based on a total of 299,970 person-years. Standardized incidence ratios (SIR) were calculated based on expected cancer rates in the general population.Results: The SIR of prostate cancer was increased in both Cohort 1 (2.5, 95% CI 1.9-3.2) and Cohort 2 (1.7, 95% CI 1.4 2.1). The risk of prostate cancer was high for relatives of patients diagnosed at an early age, and then leveled off for patients in the median age of prostate cancer diagnosis (70-79 years). However, the prostate cancer risk for relatives of patients diagnosed > or = 80 years was again statistically significantly elevated (SIR 1.8, 95% CI 1.3-2.6), suggesting a contribution of genetic factors to prostate cancer also at a late age of onset. Gastric cancer was the only other cancer type with a significantly elevated risk among the relatives. Increased risk of gastric cancer was seen only in male relatives of prostate cancer patients diagnosed at an early age, with the highest risk detected for the male relatives of prostate cancer patients diagnosed at an age of 55 years or less (SIR 5.0, 95% CI 2.8-8.2).Conclusions: Our population-based study indicates that hereditary factors may play an important role in the development of prostate cancer among the relatives of men diagnosed both at younger and older ages. This finding is relevant in the context of our observations that HPCX (hereditary prostate cancer susceptibility locus on Xq27-28) linkage in Finland is found exclusively among families with late age of onset. The association of gastric cancer with prostate cancer has not been reported previously, and may reflect the effects of a novel predisposition locus, which increases the risk to both of these common tumor types. [ABSTRACT FROM AUTHOR]

Objective: This study was initiated as a consequence of a clinical observation in one hospital of several endometrial carcinomas among users of a fixed combination of a 3-month cycle oral hormonal replacement therapy (HRT), which has been marketed in Finland since 1990. We studied whether the use of 3-month (“long”) cycle HRT is accompanied by a higher risk of endometrial cancer than the use of monthly cycle HRT. Methods: A nationwide cohort of 15,956 long cycle and 78,549 monthly cycle HRT users since January 1994 was extracted from the files of the national medical reimbursement register and followed up for cancer incidence through the Finnish Cancer Registry up to the end of 1997. Results: There were 61 cases of endometrial cancer among long cycle HRT users which significantly exceeds the average incidence in the Finnish population (standardized incidence ratio (SIRlong) 2.0, 95% confidence interval (CI) 1.6–2.6). The SIR among users of monthly cycle HRT products (SIRmonthly) was 1.3 (1.1–1.6) and the ratio SIRlong/SIRmonthly thus 1.5 (95% CI 1.1–2.1). Endometrial cancers among long cycle HRT users occur more often in early stages than in the general population and are more often highly differentiated. A survey of a sample of endometrial cancer patients in the long cycle HRT group revealed that all of them also had a history of other HRT. Users of both long and monthly cycle HRT had a similar statistically significant 30% excess of breast cancer in comparison to national incidence rates, while the incidence of colon cancer was decreased in both groups. There was no difference between the HRT groups in overall cancer morbidity. Conclusions: Our results imply that all HRT users have an increased risk of endometrial cancer, and long cycle HRT carries a higher relative risk than monthly cycle HRT. However, in this non-randomized setting it is impossible to judge whether this excess is attributable to the type of HRT or to patient selection. In-depth studies are needed to find out possible dose–response associations and to evaluate the role of potential confounders in detail. [ABSTRACT FROM AUTHOR]

Objectives: To describe the cancer risk pattern of Finnish persons with visual impairment.Methods: A cohort of 17,557 persons identified from the Finnish Register of Visual Impairment was followed-up for cancer through the Finnish Cancer Registry from 1983-95. The degree of visual impairment ranged from moderate low vision with visual acuity less than 0.3, to total blindness with no perception of light. The standardized incidence ratios (SIR) and 95% confidence intervals (CI) were calculated by primary site; the expected rates were based on national cancer incidence rates.Results: The SIR for overall cancer among totally blind men was 2.2 (CI = 1.3-3.5) while in the entire cohort the incidence was increased by only 15% (1,255 cancers observed cf 1,093 expected). Excesses were observed in both genders in cancers of the liver (SIR = 1.8, CI = 1.2-2.5) and lung (SIR = 1.5, CI = 1.3-1.7); in females in cancers of the stomach (SIR = 1.5, CI = 1.2-1.9) and the colorectum (SIR = 1.3, CI = 1.1-1.6); and in males in cancers of the kidney (SIR = 1.8, CI = 1.1-2.6) and the eye (5.8, CI = 1.9-13). The excess in lung cancer was entirely attributable to age-related macular degeneration (which is most common among smokers).Conclusions: Cancer incidence among the visually impaired tended to be increased for most cancer types. Attention should be paid to lifestyle factors underlying the observed risk increases, such as unbalanced diet. [ABSTRACT FROM AUTHOR]

Objectives: To study the asbestos-associated risk of lung cancer according to the histological type of cancer, the time of and time since diagnosis of asbestosis, the asbestos-associated risk for cancers other than lung cancer or mesothelioma, and the predictive value of asbestos-related pleural abnormalities as regards the risk of cancer.Methods: Finnish patients with asbestosis (n = 1,376) or asbestos-related benign pleural disease (n = 4,887) notified as an occupational disease since 1964 were followed-up through the Finnish Cancer Registry for cancer in 1967-95.Results: Compared with the total cancer incidence in Finland, men with asbestosis had a raised risk of lung cancer (standardized incidence ratio [SIR] = 6.7; 95% confidence interval [CI] = 5.6-7.9), mesothelioma (SIR = 32, CI = 14-60) and cancer of the larynx (SIR = 4.2, CI = 1.4-9.8). The risk of lung cancer was similarly raised for all histological types of lung cancer (the highest in insulators) and did not change markedly over time of notification or duration of follow-up. Men with benign pleural disease had a raised risk of mesothelioma (SIR = 5.5, CI = 1.5-14) and a slightly elevated risk of lung cancer (SIR = 1.3, CI = 1.0-1.8). Among women with asbestosis, significant excess was found for lung cancer and mesothelioma.Conclusion: Asbestosis and asbestos-related benign pleural disease seem to possess different predictive values as regards the risk of lung cancer. [ABSTRACT FROM AUTHOR]

The risk of hematologic malignancies was studied in Finnish patients with rheumatoid arthritis or Sjögren's syndrome, and the difference in the risk between those diseases was evaluated. The study cohorts comprised 676 patients with primary Sjögren's syndrome, 709 with secondary Sjögren's syndrome, and 9,469 with rheumatoid arthritis identified from the Finnish hospitals' national discharge register. The follow-up times were 5,336, 4,254 and 65,391 person-years, respectively. Data on the incidence of malignancies were collected from the files of the Finnish Cancer Registry. The incidence of hematologic malignancies was elevated in the study cohorts. The standardized incidence ratio (SIR) of non-Hodgkin's lymphoma was: 2.2 (95 percent confidence interval [CI] 1.5-3.1) for rheumatoid arthritis; 4.5 (CI = 1.5-11) for secondary Sjögren's syndrome; and 8.7 (CI = 4.3-16) for primary Sjögren's syndrome. The ratio of the SIR of primary Sjögren's syndrome cf rheumatoid arthritis alone was 3.9 (CI = 1.8-8.0) in non-Hodgkin's lymphoma, and 3.4 (CI = 1.2-8.1) in other hematologic cancers. The incidence of hematologic malignancies, especially that of non-Hodgkin's lymphoma, is elevated in patients with rheumatoid arthritis. It is higher in patients with secondary Sjögren's syndrome and highest in patients with primary Sjögren's syndrome. Differences in the immunologic aberration influence oncogenesis. [ABSTRACT FROM AUTHOR]

Chlorination of water rich in organic material is known to produce a complex mixture of organochlorine compounds, including mutagenic and carcinogenic substances. A historical cohort study of 621,431 persons living in 56 towns in Finland was conducted in order to assess the relation between historical exposure to drinking water mutagenicity and cancer. Exposure to quantity of mutagenicity was calculated on the basis of historical information of raw water quality and water treatment practices using an empirical equation relating mutagenicity and raw water pH, KMnO4 value and chlorine dose. Cancer cases were derived from the population-based Finnish Cancer Registry and follow-up time in the study started in 1970. Age, gender, time period, social class, and urban residence were taken into account in Poisson regression analysis of the observed numbers of cases using expected numbers of cases standardized for age and gender as a basis. Excess risks were calculated using a continuous variable for mutagenicity for 3,000 net rev/l exposure representing an average exposure in a town using chlorinated surface water. After adjustment for confounding, a statistically significant excess risk was observed for women in cancers of the bladder (relative risk [RR] = 1.48, 95 percent confidence interval [CI] = 1.01-2.18), rectum (RR = 1.38, CI = 1.03-1.85), esophagus (RR = 1.90, CI = 1.02-3.52), and breast (RR = 1.11, CI = 1.01-1.22). These results support the magnitude of excess risks for rectal and bladder cancers found in earlier epidemiologic studies on chlorination by-products and give additional information on exposure-response concerning the mutagenic compounds. Nevertheless, due to the public health importance of water chlorination, uncertainty related to the magnitude of observed risks, and the fact that excess risks were observed only for women, the results of the study should be interpreted with caution. [ABSTRACT FROM AUTHOR]

A cohort of approximately 120,000 male and 85,000 female farmers registered in the Farm Register of Finland was followed-up for cancer incidence through the Finnish Cancer Registry in 1979-93. Nearly 17,000 cancer cases were observed. Compared with the total cancer incidence of the Finnish population, both genders experienced a 17 to 18 percent decreased risk of cancer. The risks were low in smoking-related cancers, cancers associated with an urbanized way of life, and cancers inversely associated with multiparity. The only cancer sites showing significantly raised standardized incidence ratios (SIR) were lip cancer (SIR = 1.51, 95 percent confidence interval [CI] = 1.35-1.66) and Hodgkin's disease (SIR = 1.35, CI = 1.08-1.67) in males. Poisson regression was used in working out the roles of the size and type of farm after adjustment for gender, age, and geographic location of the farm. Risk of Hodgkin's disease was highest in farms without animals (SIR = 1.74, CI = 1.12-2.59). Multiple myeloma was found in excess among farmers on pig or poultry farms but not on other types of farms. [ABSTRACT FROM AUTHOR]