Nationwide cancer family ascertainment using Finnish Cancer Registry data on family names and places of birth for 35,761 prostate cancer patients

Sex-specific familial aggregation of cancers in Finland

Despite the fact that the effect of sex on the occurrence of cancers has been studied extensively, it remains unclear whether sex modifies familial aggregation of cancers. We explored sex-specific familial aggregation of cancers in a large population-based historical cohort study. We combined cancer and population registry data, inferring familial relationships from birth municipality-surname-sex (MNS) combinations. Our data consisted of 391,529 incident primary cancers in 377,210 individuals with 319,872 different MNS combinations. Cumulative sex-specific numbers of cancers were compared to expected cumulative incidence. Familial cancer risks were similar between the sexes in our population-wide analysis. Families with concordant cancer in both sexes exhibited similar sex-specific cancer risks. However, some families had exceptionally high sex-specific cumulative cancer incidence. We identified six families with exceptionally strong aggregation in males: three families with thyroid cancer (ratio between observed and expected incidence 184.6; 95% credible interval (95% CI) 33.1–1012.7, 173.4 (95% CI 65.4–374.3), and 161.4 (95% CI 29.6–785.7), one with stomach (ratio 14.4 (95% CI 6.9–37.2)), colon (ratio 15.5 (95% CI 5.7–56.3)) cancers and one with chronic lymphocytic leukaemia (ratio 33.5 (95% CI 17.2–207.6)). Our results imply that familial aggregation of cancers shows no sex-specific preference. However, the atypical sex-specific aggregation of stomach cancer, colon cancer, thyroid cancer and chronic lymphocytic leukaemia in certain families is difficult to fully explain with present knowledge of possible causes, and could yield useful knowledge if explored further.

Nationwide registry-based analysis of cancer clustering detects strong familial occurrence of Kaposi sarcoma

Many cancer predisposition syndromes are rare or have incomplete penetrance, and traditional epidemiological tools are not well suited for their detection. Here we have used an approach that employs the entire population based data in the Finnish Cancer Registry (FCR) for analyzing familial aggregation of all types of cancer, in order to find evidence for previously unrecognized cancer susceptibility conditions. We performed a systematic clustering of 878,593 patients in FCR based on family name at birth, municipality of birth, and tumor type, diagnosed between years 1952 and 2011. We also estimated the familial occurrence of the tumor types using cluster score that reflects the proportion of patients belonging to the most significant clusters compared to all patients in Finland. The clustering effort identified 25,910 birth name-municipality based clusters representing 183 different tumor types characterized by topography and morphology. We produced information about familial occurrence of hundreds of tumor types, and many of the tumor types with high cluster score represented known cancer syndromes. Unexpectedly, Kaposi sarcoma (KS) also produced a very high score (cluster score 1.91, p-value <0.0001). We verified from population records that many of the KS patients forming the clusters were indeed close relatives, and identified one family with five affected individuals in two generations and several families with two first degree relatives. Our approach is unique in enabling systematic examination of a national epidemiological database to derive evidence of aberrant familial aggregation of all tumor types, both common and rare. It allowed effortless identification of families displaying features of both known as well as potentially novel cancer predisposition conditions, including striking familial aggregation of KS. Further work with high-throughput methods should elucidate the molecular basis of the potentially novel predisposition conditions found in this study.

Screening of Finnish RAD51C founder mutations in prostate and colorectal cancer patients

BACKGROUND

Rare, heterozygous germline mutations in the RAD51C gene have been found in breast and ovarian cancer families. In the Finnish population, we have identified two founder mutations in RAD51C that increase the risk of ovarian cancer but not breast cancer in the absence of ovarian cancer. Risk for other cancers has not been studied.

METHODS

To study the role of RAD51C mutations in other common cancer types, we genotyped the Finnish RAD51C founder mutations c.837 + 1G > A and c.93delG in 1083 prostate cancer patients and 802 colorectal cancer patients using TaqMan Real-Time PCR.

RESULTS

No RAD51C mutations c.837 + 1G > A or c.93delG were detected among the prostate or colorectal cancer patients.

CONCLUSIONS

The results suggest that the RAD51C mutations do not predispose to prostate or colorectal cancer.

What can geography tell us about prostate cancer?

One of the most striking characteristics of prostate cancer is the degree of geographic variation in its patterns of occurrence and progression; this variation is apparent at local, national, and international levels. Although geographic theory, methods, and data are increasingly utilized for public health research, epidemiologic research in prostate cancer etiology and progression has not taken full advantage of the spatial sciences as partner disciplines. This article reviews the known factors influencing the biology and epidemiology of prostate cancer and some of the ways in which findings to date have benefited from geography. A model is presented for geographically integrated research in prostate cancer, with discussion of how spatially referenced data and methods could enhance approaches to answering remaining questions in prostate cancer.

New paraoxonase 1 polymorphism I102V and the risk of prostate cancer in Finnish men

BACKGROUND

Human serum paraoxonase eliminates carcinogenic lipid-soluble radicals. Because expression of the main human paraoxonase gene PON1 varies widely in humans, certain PON1 polymorphisms might be associated with increased risks of cancer. We sought new functional mutations in PON1 and determined whether known or new PON1 mutations were associated with the risk for prostate cancer in a prospective, random, population-based sample of Finnish men and in a case-control study.

METHODS

Serum paraoxonase activity was measured in 835 healthy men in the Kuopio Ischaemic Heart Disease Risk Factor Study. PON1 mutations were identified by hierarchical phenotype-targeted sequencing in DNAs from the 100 men with the lowest paraoxonase activity in this cohort, and 1595 men in the cohort were genotyped for PON1 mutations by restriction fragment length polymorphism. Multivariable analysis was used to investigate the association of known and new PON1 mutations with incident prostate cancer in 1569 cancer-free men in the cohort followed for 9-14 years. In a case-control study of Finnish men, the association of prostate cancer with the PON1 mutation identified in the cohort study was investigated in 69 case patients with familial prostate cancer and 69 unmatched healthy control subjects.

RESULTS

We identified a new single-nucleotide PON1 polymorphism associated with decreased serum paraoxonase activity that caused an isoleucine-->valine change at codon 102 in exon 4 (I102V). Of the 1569 men cancer-free at baseline, 56 (3.6%) were carriers of the I102V mutation. After adjusting for age and cholesterol-lowering medications, the relative risk for developing prostate cancer during follow-up was 6.3 (95% confidence interval [CI] = 2.1 to 19.2) among 102V allele carriers compared with noncarriers. Other PON1 alleles were not statistically significantly associated with prostate cancer. In the case-control study, patients with familial prostate cancer were more likely to be carriers of the PON1 I102V mutation than control subjects (odds ratio = 4.3, 95% CI = 0.9 to 21.5).

CONCLUSION

The PON1 102V allele appears to be associated with an increased risk for prostate cancer.