How complete and accurate are cancer registrations notified by the National Health Service Central Register for England and Wales?

The International Childhood Cancer Cohort Consortium (I4C): A research platform of prospective cohorts for studying the aetiology of childhood cancers

BACKGROUND

Childhood cancer is a rare but leading cause of morbidity and mortality. Established risk factors, accounting for <10% of incidence, have been identified primarily from case-control studies. However, recall, selection and other potential biases impact interpretations particularly, for modest associations. A consortium of pregnancy and birth cohorts (I4C) was established to utilise prospective, pre-diagnostic exposure assessments and biological samples.

METHODS

Eligibility criteria, follow-up methods and identification of paediatric cancer cases are described for cohorts currently participating or planning future participation. Also described are exposure assessments, harmonisation methods, biological samples potentially available for I4C research, the role of the I4C data and biospecimen coordinating centres and statistical approaches used in the pooled analyses.

RESULTS

Currently, six cohorts recruited over six decades (1950s-2000s) contribute data on 388 120 mother-child pairs. Nine new cohorts from seven countries are anticipated to contribute data on 627 500 additional projected mother-child pairs within 5 years. Harmonised data currently includes over 20 "core" variables, with notable variability in mother/child characteristics within and across cohorts, reflecting in part, secular changes in pregnancy and birth characteristics over the decades.

CONCLUSIONS

The I4C is the first cohort consortium to have published findings on paediatric cancer using harmonised variables across six pregnancy/birth cohorts. Projected increases in sample size, expanding sources of exposure data (eg, linkages to environmental and administrative databases), incorporation of biological measures to clarify exposures and underlying molecular mechanisms and forthcoming joint efforts to complement case-control studies offer the potential for breakthroughs in paediatric cancer aetiologic research.

Trends and projections in adenocarcinoma and squamous cell carcinoma of the oesophagus in England from 1971 to 2037

BACKGROUND

The aim of this study was to assess the incidence and trends of oesophageal adenocarcinomas (OACs) and squamous cell carcinomas (OSCCs) in England from 1971 to 2037.

METHODS

Data on 220,026 oesophageal cancers diagnosed in England between 1971 and 2013 were extracted. Multiple imputation was used to predict morphology data were missing. Incidence rates were modelled and extrapolated to 2037 using age-period-cohort models.

RESULTS

The OAC age-standardised incidence rate (ASRs) increase was greatest from 1972 to 1992 (from 4.8 to 12.3 for men and 1.1 to 3 per 100,000 for women) and slowed from 1992 to 2012 (with an increase to 17 for men and 3.8 per 100,000 for women). OSCCs rates decreased from 7.5 to 4.9 from 1972 to 2012 for men. For women, ASRs increased from 5.5 to 5.9 between 1972 and 1992 and then decreased to 4.7 per 100,000 until 2012. Rates until 2032 are predicted to stay stable for OACs and further decrease for OSCCs.

CONCLUSIONS

Imputing missing morphology allowed accurate and up-to-date estimates of trends and projections. We observed a slowing down of the increase in OAC ASRs and an overall decrease in OSCC ASRs.

Cancer incidence in English children, adolescents and young people: past trends and projections to 2030

BACKGROUND

Estimating the future incidence of cancer is important to establish sufficient service provision, however, work in this area is limited for cancer in children, adolescents, and young adults (aged 0-24).

METHODS

Age-period-cohort models were applied to cancer incidence rates for the period 1971-2013 in England. This allowed us to extrapolate past trends to 2030. We used the appropriate cancer classification developed for cancers in children and young adults, which are analysed as two separate groups to capture inherent differences.

RESULTS

The data set consisted of 119 485 records (55% among 15+ years group). Overall, cancer rates have increased over time and are expected to continue to rise into the future. Of particular interest is the increase in rates of germ cell tumours (in males) and carcinomas (in females) in young adults, since their rates are projected to further increase over time.

CONCLUSIONS

The estimated future incidence rates provide a baseline for different cancer subtypes, which will allow policymakers to develop a contingency plan to deal with future demands.

Relationship between paediatric CT scans and subsequent risk of leukaemia and brain tumours: assessment of the impact of underlying conditions

BACKGROUND

We previously reported evidence of a dose-response relationship between ionising-radiation exposure from paediatric computed tomography (CT) scans and the risk of leukaemia and brain tumours in a large UK cohort. Underlying unreported conditions could have introduced bias into these findings.

METHODS

We collected and reviewed additional clinical information from radiology information systems (RIS) databases, underlying cause of death and pathology reports. We conducted sensitivity analyses excluding participants with cancer-predisposing conditions or previous unreported cancers and compared the dose-response analyses with our original results.

RESULTS

We obtained information from the RIS and death certificates for about 40% of the cohort (n∼180 000) and found cancer-predisposing conditions in 4 out of 74 leukaemia/myelodysplastic syndrome (MDS) cases and 13 out of 135 brain tumour cases. As these conditions were unrelated to CT exposure, exclusion of these participants did not alter the dose-response relationships. We found evidence of previous unreported cancers in 2 leukaemia/MDS cases, 7 brain tumour cases and 232 in non-cases. These previous cancers were related to increased number of CTs. Exclusion of these cancers reduced the excess relative risk per mGy by 15% from 0.036 to 0.033 for leukaemia/MDS (P-trend=0.02) and by 30% from 0.023 to 0.016 (P-trend<0.0001) for brain tumours. When we included pathology reports we had additional clinical information for 90% of the cases. Additional exclusions from these reports further reduced the risk estimates, but this sensitivity analysis may have underestimated risks as reports were only available for cases.

CONCLUSIONS

Although there was evidence of some bias in our original risk estimates, re-analysis of the cohort with additional clinical data still showed an increased cancer risk after low-dose radiation exposure from CT scans in young patients.

Do depressive symptoms predict cancer incidence?: 17-year follow-up of the Whitehall II study

OBJECTIVE

To explore the association between depressive symptom history and cancer incidence.

METHODS

Affective/emotional depressive symptoms were assessed using the General Health Questionnaire (GHQ-30) depression sub-scale across phase 1 (1985-1988), phase 2 (1989-1990), and phase 3 (1991-1994) of the Whitehall II prospective cohort study; 'chronic'=depressive episode at phase 1, 2 and 3; 'new'=depressive episode at phase 3 only. Cancer incidence was obtained from the National Health Service Central Register with an average follow-up of 15.6 years (range 0.08-17.4). The study sample consisted of 6983 participants, aged 35-55 years at baseline. Results were adjusted for age, sex, socio-economic position, health behaviours, health status/conditions, medication, and social support.

RESULTS

Over a 17.4 year follow-up, chronic depressive symptoms did not increase the risk of cancer incidence compared to those who never experienced symptoms (hazard ratio (HR)=1.03, 95% confidence interval (CI): 0.71-1.49). Participants who experienced new depressive symptoms had an increased risk of cancer incidence in the first 9 years of follow-up (HR=1.89, 95% CI: 1.23-2.90) but no increased risk in later years (HR=0.84, 95% CI: 0.52-1.35).

CONCLUSION

Chronic depressive symptoms were not associated with cancer incidence. In contrast, new-onset symptoms were associated with a substantially increased risk, possibly due to reverse causality.

Variability in date of prostate cancer diagnosis: a comparison of cancer registry, pathology report, and electronic health data sources

PURPOSE

The date of cancer diagnosis is a critical data element for clinical care and research. Because this date can be abstracted from various data sources, its comparability from source to source is unclear. This study compared the date of diagnosis from multiple sources within the same population of prostate cancer patients.

METHODS

We linked cancer registry, pathology report, and electronic health data sources from the Kaiser Permanente Southern California health data systems for a cohort of 22,666 members diagnosed with prostate cancer between 2000 and 2010. The magnitude and direction of the differences in date of diagnosis were assessed for each date pairwise comparison. We reviewed 454 medical records to determine reasons for date discrepancies.

RESULTS

Among the date pairwise comparisons, differences in date of diagnosis spanned from 9.6 years earlier to 10 years later than each other. However, the overall median difference ranged from 1 to 16 days, thus suggesting that the vast majority of the date differences were small. Chart review results identified major categories of date discrepancies.

CONCLUSIONS

These data demonstrate variability in date of diagnosis across these data sources. This variability may have implications for epidemiologic estimates or patient identification in research studies using different data sources.

The influence of anti-TNF therapy upon incidence of keratinocyte skin cancer in patients with rheumatoid arthritis: longitudinal results from the British Society for Rheumatology Biologics Register

Objectives

To compare the risk of keratinoctye skin cancer (basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)) in patients treated for rheumatoid arthritis (RA) compared with the general population, and to determine whether anti-tumour necrosis factor (TNF) therapy exacerbates this risk.

Methods

Patients with RA enrolled in the British Society for Rheumatology Biologics Register, a prospective national cohort established in 2001 to monitor the safety of anti-TNF, were followed until 2008. 11 881 patients treated with anti-TNF were compared with 3629 patients receiving non-biological disease-modifying antirheumatic drugs (nbDMARD). Standardised incidence ratios (SIR) were calculated for each cohort and rates between cohorts were compared using Cox proportional HR, adjusted using inverse probability of treatment weighting.

Results

SIR for skin cancer was increased in both cohorts compared with the English population: SIR 1.72 (95% CI 1.43 to 2.04) anti-TNF; 1.83 (95% CI 1.30 to 2.50) nbDMARD only. In patients without previous skin cancer, BCC incidence per 100 000 patient-years was 342 (95% CI 290 to 402) after anti-TNF and 407 (95% CI 288 to 558) after nbDMARD. HR after anti-TNF adjusted for treatment weighting was 0.95 (95% CI 0.53 to 1.71). SCC incidence per 100 000 patient-years: anti-TNF 53 (95% CI 33 to 79); nbDMARD 43 (95% CI 12 to 110); adjusted HR 1.16 (95% CI 0.35 to 3.84).

Conclusions

Skin cancers were increased among treated patients with RA. No evidence was found that anti-TNF therapy exacerbates the risk of BCC or SCC but this cannot be excluded. Patients with RA should use sun protection and be monitored for skin cancer.

Primary excision of cutaneous melanoma: does the location of excision matter

Melanoma is diagnosed more quickly if primarily excised in primary care, but current guidelines discourage this. The reports of all melanomas excised in north-east Scotland between 1991 and 2007 were analysed for adequacy of excision. Reports were analysed blinded as to source. Of primary biopsies performed in primary care, 72.5% were reported as completely excised, compared with 69.7% of those performed in secondary care (P<0.612). The difference remained non-significant following adjustment for important confounders.

Influence of anti-tumor necrosis factor therapy on cancer incidence in patients with rheumatoid arthritis who have had a prior malignancy: results from the British Society for Rheumatology Biologics Register

Objective

To explore the influence of anti–tumor necrosis factor (anti-TNF) therapy upon the incidence of cancer in patients with rheumatoid arthritis (RA) and prior malignancy.

Methods

Using data from the British Society for Rheumatology Biologics Register, a national prospective observational study established in 2001, we identified 293 patients with a prior malignancy from over 14,000 patients with RA. We compared rates of incident malignancy in 177 anti-TNF–treated patients and 117 patients with active RA treated with traditional disease-modifying antirheumatic drugs (DMARDs), all with prior malignancy. One patient switched therapy and contributed to both cohorts.

Results

The rates of incident malignancy were 25.3 events/1,000 person-years in the anti-TNF cohort and 38.3/1,000 person-years in the DMARD cohort, generating an age- and sex-adjusted incidence rate ratio of 0.58 (95% confidence interval 0.23–1.43) for the anti-TNF–treated cohort compared with the DMARD cohort. Of the patients with prior melanomas, 3 (18%) of 17 in the anti-TNF cohort developed an incident malignancy, compared with 0 of 10 in the DMARD cohort.

Conclusion

The way in which UK rheumatologists are selecting patients with RA and prior malignancy to receive anti-TNF therapy is not leading to an increased risk of incident malignancy. Although reassuring, these results should not be interpreted as indicating that it is safe to treat all RA patients with prior malignancy with anti-TNF therapy.

Access to specialized pediatric cancer care in Switzerland

BACKGROUND

Specialized pediatric cancer centers (PCCs) are thought to be essential to obtain state-of-the-art care for children and adolescents. We determined the proportion of childhood cancer patients not treated in a PCC, and described their characteristics and place of treatment.

PROCEDURE

The Swiss Childhood Cancer Registry (SCCR) registers all children treated in Swiss PCCs. The regional cancer registries (covering 14/26 cantons) register all cancer patients of a region. The children of the SCCR with data from 7 regions (11 cantons) were compared, using specialized software for record linkage. All children <16 years of age at diagnosis with primary malignant tumors, diagnosed between 1990 and 2004, and living in one of these regions were included in the analysis.

RESULTS

22.1% (238/1,077) of patients recorded in regional registries were not registered in the SCCR. Of these, 15.7% (169/1,077) had never been in a PCC while 6.4% (69/1,077) had been in a PCC but were not registered in the SCCR, due to incomplete data flow. In all diagnostic groups and in all age groups, a certain proportion of children was treated outside a PCC, but this proportion was largest in children suffering from malignant bone tumors/soft tissue sarcomas and from malignant epithelial neoplasms, and in older children. The proportion of patients treated in a PCC increased over the study period (P < 0.0001).

CONCLUSIONS

One in six childhood cancer patients in Switzerland was not treated in a PCC. Whether these patients have different treatment outcomes remained unclear.

Identifying patients with a cancer diagnosis using general practice medical records and Cancer Registry data

BACKGROUND

The medical records of patients with cancer need to accurately record diagnoses for professionals to provide quality care. Aims. (i) To develop a methodology which identifies medical records of patients with a cancer diagnosis. (ii) To describe the effectiveness of search strategies to identify all patients in primary care with a cancer diagnosis compared with a diagnosis identified by a Cancer Registry.

METHODS

The design of the study was a retrospective analysis of primary care medical records. Five general practices were recruited in the UK. The completeness and correctness of searches were measured and compared both within the practices and compared with a diagnosis identified by a Cancer Registry.

RESULTS

One in five of all primary care patients with cancer was not identified when a search for all patients with cancer was conducted using electronic codes for malignancy. One in five patient records with an electronic code for a malignancy that was confirmed by registration with the Cancer Registry actually lacked the necessary documentation to verify the cancer type, date of diagnosis or any other aspect of the malignant condition. Overall, electronic codes for cancer in these medical records have a poor level of completeness (29.4%) and correctness (65.6%) when compared with the Cancer Registry.

CONCLUSIONS

The electronic codes in five general practices were not able to identify all patients on the practice lists with a cancer diagnosis. Practices will only be able to comply with guidelines and meet quality targets if they can identify all of their current patients with a cancer diagnosis and will require information from a Cancer Registry in order to do this.

Cancer risk among users of oral contraceptives: cohort data from the Royal College of General Practitioner's oral contraception study

OBJECTIVE

To examine the absolute risks or benefits on cancer associated with oral contraception, using incident data.

DESIGN

Inception cohort study.

SETTING

Royal College of General Practitioners' oral contraception study.

PARTICIPANTS

Directly standardised data from the Royal College of General Practitioners' oral contraception study.

MAIN OUTCOME MEASURES

Adjusted relative risks between never and ever users of oral contraceptives for different types of cancer, main gynaecological cancers combined, and any cancer. Standardisation variables were age, smoking, parity, social class, and (for the general practitioner observation dataset) hormone replacement therapy. Subgroup analyses examined whether the relative risks changed with user characteristics, duration of oral contraception usage, and time since last use of oral contraception.

RESULTS

The main dataset contained about 339,000 woman years of observation for never users and 744,000 woman years for ever users. Compared with never users ever users had statistically significant lower rates of cancers of the large bowel or rectum, uterine body, and ovaries, tumours of unknown site, and other malignancies; main gynaecological cancers combined; and any cancer. The relative risk for any cancer in the smaller general practitioner observation dataset was not significantly reduced. Statistically significant trends of increasing risk of cervical and central nervous system or pituitary cancer, and decreasing risk of uterine body and ovarian malignancies, were seen with increasing duration of oral contraceptive use. Reduced relative risk estimates were observed for ovarian and uterine body cancer many years after stopping oral contraception, although some were not statistically significant. The estimated absolute rate reduction of any cancer among ever users was 45 or 10 per 100,000 woman years, depending on whether the main or general practitioner observation dataset was used.

CONCLUSION

In this UK cohort, oral contraception was not associated with an overall increased risk of cancer; indeed it may even produce a net public health gain. The balance of cancer risks and benefits, however, may vary internationally, depending on patterns of oral contraception usage and the incidence of different cancers.

Risk of mortality and cancer incidence in Barrett's esophagus

BACKGROUND

There are very few prospective follow-up studies of Barrett esophagus (BE) cohorts assessing the risk of extraesophageal cancer incidence or mortality. Such studies are necessary in order to understand the overall risks of cancer and death experienced by patients with BE.

METHODS

A cohort of 502 patients with BE were identified at Leeds General Infirmary, England. Mortality and cancer incidence information were provided by the Office for National Statistics. Standardized mortality ratios (SMR) and standardized incidence ratios (SIR) were calculated using indirect standardization.

RESULTS

All-cause mortality was found to be elevated in patients with BE [SMR, 1.21; 95% confidence interval (95% CI), 1.06, 1.37] and remained so after esophageal cancers were excluded (SMR, 1.16; 95% CI, 1.01-1.32). Increased mortality risks were also found for malignant neoplasms of the esophagus (SMR, 7.26; 95% CI, 3.87-12.42) and diseases of the digestive system (SMR, 2.03; 95% CI, 1.11-3.40). The remaining disease categories produced no altered risk estimates. Circulatory disease mortality was borderline statistically significant (SMR, 1.24; 95% CI, 1.00-1.52; P = 0.053) for those with a specialized intestinal metaplasia diagnosis of BE. In the cancer incidence analyses, esophageal malignancies (SIR, 8.66; 95% CI, 4.73-14.53) and esophageal adenocarcinomas (SIR, 14.29; 95% CI, 7.13-22.56) were found to be increased in BE. All remaining analyses provided unaltered risks, including that of colorectal cancer.

CONCLUSIONS

This study has shown evidence of an increased risk of esophageal cancer incidence and mortality in BE. It has also shown that those who have a histologic BE diagnosis may also have an increased risk of circulatory disease mortality.

Consistency and accuracy of diagnostic cancer codes generated by automated registration: comparison with manual registration

Background

Automated procedures are increasingly used in cancer registration, and it is important that the data produced are systematically checked for consistency and accuracy. We evaluated an automated procedure for cancer registration adopted by the Lombardy Cancer Registry in 1997, comparing automatically-generated diagnostic codes with those produced manually over one year (1997).

Methods

The automatically generated cancer cases were produced by Open Registry algorithms. For manual registration, trained staff consulted clinical records, pathology reports and death certificates. The social security code, present and checked in both databases in all cases, was used to match the files in the automatic and manual databases. The cancer cases generated by the two methods were compared by manual revision.

Results

The automated procedure generated 5027 cases: 2959 (59%) were accepted automatically and 2068 (41%) were flagged for manual checking. Among the cases accepted automatically, discrepancies in data items (surname, first name, sex and date of birth) constituted 8.5% of cases, and discrepancies in the first three digits of the ICD-9 code constituted 1.6%. Among flagged cases, cancers of female genital tract, hematopoietic system, metastatic and ill-defined sites, and oropharynx predominated. The usual reasons were use of specific vs. generic codes, presence of multiple primaries, and use of extranodal vs. nodal codes for lymphomas. The percentage of automatically accepted cases ranged from 83% for breast and thyroid cancers to 13% for metastatic and ill-defined cancer sites.

Conclusion

Since 59% of cases were accepted automatically and contained relatively few, mostly trivial discrepancies, the automatic procedure is efficient for routine case generation effectively cutting the workload required for routine case checking by this amount. Among cases not accepted automatically, discrepancies were mainly due to variations in coding practice.

Quality control of automatically defined cancer cases by the automated registration system of the Venetian Tumour Registry. Quality control of cancer cases automatically registered

BACKGROUND

In the Venetian Tumour Registry a substantial quota of cases (55%) is accepted using an algorithm that automatically evaluates diagnostic evidence: this study aims at assessing the reliability of the information produced in this way.

METHODS

A reabstraction study was conducted, which put a stratified sample of 1539 automatically accepted cases through a double-blind manual revision.

RESULTS

A significantly higher proportion of prevalent cases were found among breast, prostate and larynx cancer cases without microscopic confirmation, while there is a clear strong inverse relationship between the number of concordant diagnostic sources and the proportions of discordant diagnoses: cases based only on a single cytology record are particularly unreliable. A small number of multiple cancers are not detected because of one of the rules applied.

CONCLUSION

The overall proportion of incorrect decisions is not high and similar to those reported by other registries, but errors are correlated to the diagnostic evidence pattern. As a further check, we decided to revise clinical cases for the three sites mentioned manually, in order to reduce the numbers proportion of both prevalent cases, and all cytology-based diagnoses, so as to reduce the number of 'false positives'. Coverage of hospital discharge source has been extended in order to decrease the proportion of cases based only on pathology records.

Risk of malignancy in diagnosed coeliac disease: a 24-year prospective, population-based, cohort study

BACKGROUND

There is recent evidence from studies of hospitalized and of undiagnosed patients that the risk of lymphoma for people with coeliac disease may be lower than previously thought. In addition, there have been no precise estimates of small bowel lymphoma risk due to a lack of population data.

AIM

To examine these and other malignant risks in a cohort of patients more typical of those seen in routine clinical practice.

METHODS

A prospective cohort study of incident malignancy rates in patients with coeliac disease in southern Derbyshire compared with general population figures.

RESULTS

During 5684 person years of follow-up 31 malignancies (excluding non-melanoma skin cancer) occurred in comparison with 30.30 expected [standardized incidence ratio (SIR) 1.02 (0.69-1.45)]. There were four non-Hodgkin's lymphomas (0.69 expected) SIR 5.81 (1.58-14.86), of which one originated in small bowel (0.02 expected) SIR 40.51 (1.03-225.68). GI malignancy occurred in nine (5.71 expected) SIR 1.58 (0.72-2.99), and breast cancer in three (5.08 expected) SIR 0.59 (0.12-1.73).

CONCLUSIONS

There is no increase in the risk of incident malignancy in this population and the risk of non-Hodgkin's lymphoma in general or of the small bowel is lower than previously found from UK coeliac cohorts.

Under-ascertainment of multiple myeloma among participants in UK atmospheric atomic and nuclear weapons tests

An inter-comparison of cases of multiple myeloma among UK participants in the UK's atmospheric atomic and nuclear weapons tests ascertained by direct follow up methods detected at least a third more cases than a strategy relying solely on data linkage between the Office of National Statistics and the Service Records Offices. These finding have implications for the conduct and robustness of follow up studies of long term health effects among participants in nuclear weapons tests.

Cervical screening and health inequality in England in the 1990s

STUDY OBJECTIVE

s: To examine changing inequality in the coverage of cervical screening and its relation to organisational aspects of primary care and to inequality in cervical cancer incidence and mortality.

DESIGN

Retrospective time trends analysis (1991-2001) of screening coverage and cervical cancer incidence and mortality in England.

SETTING

The 99 district health authorities in England, as defined by 1999 boundaries were used to create a time series of incidence and mortality rates from cervical cancer per 100 000 population. A subset of 60 district health authorities were used to construct a time series of screening coverage data and GP and practice characteristics. Health authorities were categorised into one of three "deprivation" groups using the Townsend Deprivation Index.

PARTICIPANTS

Women aged <35 and 35-64 were selected from health authority populations as the main focus of the study.

RESULTS

Cervical cancer screening coverage was consistently higher in affluent areas from 1991-9 but ratio rates of inequality between affluent and deprived health authorities narrowed over time. The increase in coverage in deprived areas was most closely associated with an increase in the number of practice nurses. Cervical cancer incidence and mortality rates were consistently higher in deprived health authorities, but inequality decreased. Screening coverage and cervical cancer rates were highly negatively correlated in deprived health authorities.

CONCLUSION

A primary health care intervention such as an organised programme of cervical screening can contribute to reducing inequality in population health.

Study of completeness of registration at the Estonian cancer registry

Every cancer registry should be able to quantify the level of completeness of registration. The current study describes a routine quality control procedure in the Estonian Cancer Registry (ECR) for assessing the completeness of registration. The registry's database was compared with the databases of the Tartu University Lung Clinic and the Maarjamõisa Hospital of the Tartu University Clinics, and active retrieval to obtain missing cancer cases diagnosed in 1998 was carried out. The overall completeness of case ascertainment based on this study was 90.8%. As a result of this procedure, 67 cases of malignant neoplasms (1.1% of the total number of incident cancer cases for 1998) and 11 cases of other reportable neoplasms were detected and recorded at the ECR. Cancers of the lung, thyroid gland and prostate were most frequently under-notified. For these sites, the number of cancer cases for 1998 for Estonia as a whole increased 2.6%, 11.8% and 2.2%, respectively. To conclude, the existence of electronic databases is a positive development, but cancer registrars still need to employ labour-intensive methods to validate diagnostic codes and to decide whether to include in the ECR cases found by active retrieval. Based on the findings of our study, which is the first one of its kind in Estonia, the completeness of cancer reporting varied by cancer site, and it appeared to be a substantial concern for several sites.

Childhood solid tumours in relation to infections in the community in Cumbria during pregnancy and around the time of birth

In a retrospective cohort study of all 99 976 live births in Cumbria, 1975-1992, we investigated whether higher levels of community infections during the mother's pregnancy and in early life were risk factors for solid tumours (brain/spinal and other tumours), diagnosed 1975-1993 under age 15 years. Logistic regression was used to relate risk to incidence of community infections in three prenatal and two postnatal quarters. There was an increased risk of brain/spinal tumours among children exposed around or soon after birth to higher levels of community infections, in particular measles (OR for trend=2.1, 95%CI : 1.3-3.6, P=0.008) and influenza (OR for exposure=3.3, 95%CI : 1.5-7.4, P=0.005). There was some evidence of an association between exposure to infections around and soon after birth and risk of other tumours, but this may have been a chance finding. The findings are consistent with other recent epidemiological studies suggesting brain tumours may be associated with perinatal exposure to infections.

Leukaemia and non-Hodgkin's lymphoma in children of male Sellafield radiation workers

Our objective was to investigate if there was (i) an excess risk of leukaemia/non-Hodgkin's lymphoma among children of male radiation workers at the Sellafield nuclear installation in Cumbria, northwest England; (ii) a dose-response relationship between fathers' preconceptional irradiation and their children's risk of leukaemia/non-Hodgkin's lymphoma; and (iii) whether any observed association could be explained by demographic factors. We performed a cohort study of live births, 1950-1991 in Cumbria, followed up to age 25 years or the end of 1991, comparing the risk of leukaemia/non-Hodgkin's lymphoma among all 9,859 children of male radiation workers to that among all 256,851 children of non-Sellafield fathers. Children of radiation workers had a higher risk of leukaemia/non-Hodgkin's lymphoma than other children [rate ratio (RR) = 1.9, 95% confidence interval (CI) 1.0-3.1, p = 0.05]. Adjustment for population mixing greatly reduced the excess risk in the village of Seascale, adjacent to Sellafield, but had little effect elsewhere. The risk increased significantly with father's total preconceptional external radiation dose (RR(100mSv) = 1.6, 95% CI 1.0-2.2, p = 0.05). This dose-response was not reduced by adjustment for population mixing. Although our 13 exposed cases included 10 considered previously (Gardner et al., BMJ 1990;300:423-34), we used a cohort rather than a case-control design, with wider temporal and geographic boundaries, and confirmed the statistical association between father's preconceptional irradiation and child's risk of leukaemia/non-Hodgkin's lymphoma that they reported. The possibility remains that paternal preconceptional irradiation may be a risk factor for leukaemia/non-Hodgkin's lymphoma, and this effect may not be confined to Seascale.