Quality measures of the population-based Finnish Cancer Registry indicate sound data quality for solid malignant tumours

This registry‐linkage study evaluates familial aggregation of cancer among relatives of a population‐based series of early‐onset (≤40 years) cancer patients in Finland. A cohort of 376,762 relatives of early‐onset cancer patients diagnosed between 1970 and 2012 in 40,538 families was identified. Familial aggregation of early‐onset breast, colorectal, brain and other central nervous system (CNS) cancer and melanoma was explored by standardized incidence ratios (SIR), stratified by relatedness. Gender‐, age‐ and period‐specific population cancer incidences were used as reference. Cumulative risks for siblings and offspring of the proband up to age ≤40 years were also estimated. Almost all early‐onset cancers were sporadic (98% or more). Among first‐degree relatives, SIR was largest in colorectal cancer (14, 95% confidence interval 9.72–18), and lowest in melanoma (1.93, 1.05–3.23). Highest relative‐specific SIRs were observed for siblings in families, where also parent had concordant cancer, 90 (43–165) for colorectal cancer and 29 (11–64) for CNS cancer. In spouses, all SIRs were at population level. Cumulative risk of colorectal cancer by age 41 was 0.98% in siblings and 0.10% in population, while in breast cancer the corresponding risks were 2.05% and 0.56%. In conclusion, early‐onset cancers are mainly sporadic. Findings support high familial aggregation in early‐onset colorectal and CNS cancers. Familial aggregation in multiplex families with CNS cancers was mainly attributed to neurofibromatosis and in colorectal cancer to FAP‐ and HNPCC‐syndromes. The pattern of familial aggregation of early‐onset breast cancer could be seen to support very early exposure to environmental factors and/or rare genetic factors.

Section: Methodsmentioning

confidence: 99%

“…Data on cancers are of high coverage 15 and are also complete for date of the diagnosis and family members' relatedness to the proband. Data on cancers are of high coverage 15 and are also complete for date of the diagnosis and family members' relatedness to the proband.…”

Section: Methodsmentioning

confidence: 99%

Familial aggregation of early‐onset cancers

Heikkinen

Madanat‐Harjuoja

Seppä

et al. 2019

“…All residents of the four Nordic countries are assigned a unique country‐specific personal identification number, which is used in all registries and makes accurate record linkage possible. Overall completeness and accuracy of the registries is very high …”

Section: Methodsmentioning

confidence: 99%

Pregnancy complications and subsequent breast cancer risk in the mother: a Nordic population‐based case–control study

Troisi

Ording

Grotmol

et al. 2018

Certain features of pregnancy are important risk factors for breast cancer, such as protection afforded by young age at first birth. Preeclampsia, a pregnancy complication, is associated with reduced maternal breast cancer risk. However, questions remain regarding causality, biological mechanisms and the relation of other hypertensive conditions to risk. We conducted a population-based case-control study of breast cancer cases (n = 116,196) in parous women identified through linkage of birth and cancer registries in Denmark, Finland, Norway and Sweden (1967-2013), including up to 10 matched controls per case (n = 1,147,192) sampled from the birth registries (complete data were not available on all variables). Odds ratios (ORs) with 95% confidence intervals (CIs) were derived from unconditional logistic regression models including matching factors (country, maternal birth year) and parity. Hypertension diagnosed before pregnancy (OR 0.87; 95% CI 0.78-0.97), gestational hypertension (OR 0.90; 95% CI 0.86-0.93) and preeclampsia (OR 0.91; 95% CI 0.88-0.95) were associated with reduced breast cancer risk. Results remained similar after adjustment for smoking and maternal body mass index before first pregnancy, and were generally similar stratified by parity, age at breast cancer diagnosis, time since first and last birth, sex of the offspring and calendar time. Except for retained placenta (OR 1.14; 95% CI 0.98-1.32), no other pregnancy complication appeared associated with breast cancer risk. The mechanisms mediating the modest risk reductions for history of preeclampsia or hypertension preceding or arising during pregnancy, and possible increased risk with history of retained placenta are unknown and warrant further laboratory, clinical and epidemiological investigation.

“…The coverage of the FCR is high, 96% for solid tumors and 86% for hematological malignancies. Of all cancers, 93% were morphologically verified . Data on cancer patients include the PIC, details on cancer (site, histology and malignancy), treatment data (radiotherapy, chemotherapy, surgery and hormonal) and month as well as year of diagnosis.…”

Section: Methodsmentioning

confidence: 99%

Use of fertility drugs in early‐onset female cancer survivors—A Finnish register‐based study on 8,929 survivors

Melin

Madanat‐Harjuoja

Hirvonen

et al. 2019

Self Cite

Advances in multimodality cancer treatments have increased the risk of long‐term complications in early‐onset cancer survivors. For female cancer survivors, these include diminished reproductive function, often resulting in a narrowed fertile window. The aim of our study was to evaluate the use of fertility treatments in cancer survivors (aged 0–39 years at diagnosis) compared to siblings. Data from Finnish registers on cancer, birth and prescribed medications were merged to identify 8,929 survivors and 9,495 siblings without previous deliveries. Fertility drug purchases from 1993 to 2012 at the age of 16–41 years were included. A Poisson regression model was used to estimate incidence rate ratios (IRRs) for the use of fertility drugs, adjusting for age and calendar time at fertility drug purchase. Fertility treatments were more common in survivors compared to siblings, as 6.1% of survivors compared to 3.8% of siblings had bought fertility drugs (IRR 1.43, 95% confidence interval [CI] 1.25–1.65). A subclassification of fertility treatments into ovulation inductions and assisted reproductive technology (ART), showed increased use of ART (IRR 2.41, 95% CI 1.97–2.96), whereas the use of ovulation induction was similar in survivors and siblings. Analyses by calendar time periods showed the use of ART to be significantly higher in the most recent decade, from 2003 onwards. We conclude that cancer survivors have an increased risk for subfertility, which is why fertility counseling is important. However, our results mirror a more active approach among clinicians towards fertility treatments in cancer survivors during the most recent years.