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Biomedical subjects

N E Day

Publications and source records attributed to N E Day.

At least 19 recordsLinked to original sources
PubMed1992

Lung cancer following Hodgkin's disease: a case-control study.

It is recognized that survivors of Hodgkin's disease are at a substantially increased risk of lung cancer. A collaborative group of population-based cancer registries and major treatment centers carried out a case-control study, in which 98 cases of lung cancer were identified in patients who had survived at least 1 year following a diagnosis of Hodgkin's disease. A total of 259 matched controls were selected from patients with Hodgkin's disease who did not develop subsequent lung cancer, and for both cases and controls detailed information was abstracted from medical records concerning stage and treatment of Hodgkin's disease. Patients treated with chemotherapy alone had about twice the risk of developing lung cancer than those treated by radiotherapy alone or both modalities. There was no increase in risk with cumulative number of cycles of chemotherapy. Among patients treated with radiotherapy alone, there was an increase in risk related to estimated radiation dose to the lung. There was also a strong association between cigarette smoking and the risk of lung cancer. The finding of a higher risk following chemotherapy than following radiotherapy was unexpected, but could not be explained by any identified methodological flaws. A plausible inference from the study is that all forms of Hodgkin's disease therapy are carcinogenic to the lung and that, in particular, chemotherapy is associated with an increase in risk which is at least comparable to and perhaps higher than the risk produced by radiotherapy.

Antineoplastic Agents↗
PubMed1992

Pickled vegetables in the aetiology of oesophageal cancer in Hong Kong Chinese.

Oesophageal cancer is common in Chinese populations, but individual-based epidemiological studies have provided little explanation. A case control study with 400 cases and 1598 controls (800 hospital and 798 general practice) was conducted among Hong Kong Chinese. In multivariate analyses, statistically significant effects on risk were detected for several potentially preventable exposures with high attributable risks (ARs). These included preference for consuming drinks or soups at high temperature (AR = 14%), infrequent consumption of green leafy vegetables (AR = 15%) and citrus fruits (AR = 26%), ingestion of pickled vegetables (AR = 29%), tobacco smoking (AR = 44%), and alcohol drinking (AR = 48%). On the assumption of multiplicative risk, the combined AR due to these exposures was 89%. This is the first case control study to show an association between pickled vegetable consumption and oesophageal cancer risk. The finding considerably strengthens the evidence for carcinogenicity of N-nitroso compounds in man and helps to explain the very high risk among Chinese.

Aged↗
PubMed1992

Conservative treatment of mild/moderate cervical dyskaryosis: long-term outcome.

There is some controversy about the management of women with mild or moderate dyskaryotic cervical smears. To assess the strategy of an established cervical cytology screening programme (Grampian region, northeast Scotland) we identified 500 women who had had mild or moderate cervical dyskaryosis in 1978 or 1979, and 500, matched by age, who had had a normal smear at that time. Follow-up smear results and any subsequent investigation by colposcopy, cone biopsy, or hysterectomy, with biopsy result were recorded. Of the 500 women who initially had an abnormal smear, 300 (60%) had a smear that was normal or inflammatory at their last visit (after seven years' median follow-up). 184 (37%) had undergone biopsy, 97 (19%) of whom were cervical intraepithelial neoplasia grade III or worse. Survival curves for time to biopsy and ten-year biopsy rates show that women with an abnormal smear before their baseline year were the most likely to have a subsequent biopsy. Older women had a biopsy less often and at biopsy were more likely to have minor abnormalities. Mild or moderate dyskaryotic smears should not be an indication for immediate referral for colposcopy, since under a conservative management policy most women return to normal without needing treatment. Nevertheless, the increased risk associated with abnormal smears justifies rigorous surveillance.

Biopsy↗
PubMed1992

Cluster randomization in large public health trials: the importance of antecedent data.

Large-scale public health trials are often randomized by geographic or administrative clusters, for reasons of financial or organizational exigency. In this paper, we deal with the situation where the dependent variable is a count of events, such as mortality from, or incidence of a given disease. Simulation results show that this design may decrease power by more than 50 per cent. The lost power can largely be replaced by incorporating information on the dependent variable, within clusters, before the start of the trial. The pretrial and trial data can be analysed by negative trinomial models.

Breast Neoplasms↗
PubMed1992

Risk factors for breast cancer by age and menopausal status: a case-control study in Singapore.

A case-control study was conducted among Singapore Chinese women, comprised of 200 histologically confirmed cases of breast cancer and 420 hospital controls. Subjects were interviewed on family history of breast cancer, social and demographic characteristics, reproductive history, and diet one year prior to interview. Differences in risk factors were observed according to menopausal status. In the premenopausal group, the most consistently significant nondietary effect was an increased risk with late age at first birth. In postmenopausal women, the most consistent nondietary effects were increased risks with nulliparity, tall stature, high educational status, and a family history of breast cancer. In premenopausal women, the strongest dietary effects were low risks with high intakes of polyunsaturated fatty acids (PUFA), beta-carotene, soya protein as a proportion of all protein, and a high risk with high red-meat intake. No dietary effects were observed in postmenopausal women. Examination of effects by 10-year age groups suggested that the differences in the effects of age at first birth, nulliparity, height, education, beta-carotene intake, and PUFA intake between premenopausal and postmenopausal women were at least partly attributable to age-related differences in the baseline distributions of these variables. The variation in the effects of red meat and soya protein appeared to be attributable mainly to menopausal status itself, which is consistent with the hypothesis that these factors operate on risk by way of hormonal mechanisms.

Adult↗
PubMed1992

Oesophageal cancer mortality in Europe: paradoxical time trend in relation to smoking and drinking.

The main risk factors for oesophageal cancer previously identified in western Europe are tobacco smoking and alcohol drinking. However, a study of the time trend from 1951 to 1985 of the mortality from oesophageal cancer in 17 European countries shows that, except among the younger age groups in men, oesophageal cancer had either decreased or increased only slightly in most countries. This trend differed from that of lung cancer, cirrhosis and alcohol consumption which had in general increased substantially during the period. The results strongly suggest that population-wide changes in certain undetermined risk/protective factor(s), one possibility of which is the consumption of fruit, had overridden the effect of tobacco and alcohol and resulted in a reduction of oesophageal cancer risk. Apart from further efforts to reduce smoking and drinking, studies to identify the factor(s) will be of great public health importance to the prevention of oesophageal cancer.

Aged↗
PubMed1992

Oesophageal cancer in the Republic of Karakalpakstan.

Regional and temporal patterns of variation in the incidence of cancer of the oesophagus in the Central Asian republic of Karakalpakstan were analysed. Karakalpakstan (population about 1200,000) is an area with high rates of this disease. Incidence data within regions (data from 1988-1989), ethnic groups (data from 1987-1989) and calendar periods (data from 1973-1987) were available for analysis, with corresponding official population estimates. No significant difference was observed between rates in urban and rural environments, although significant regional variation was observed (P less than 0.05). The highest rate observed was in the Muinak, the northern region, with world age-standardized rates (ASR) of 125.96 for males and 150.65 for females. There was a very significant difference among ethnic groups (P less than 0.001). The ethnic group with the highest incidence was the Kazakh people, with an ASR of 68.0 in males and 86.3 in females. Incidence in the republic as a whole declined in the period from 1973 to 1987. Incidence of cancer of the oesophagus is still high in Karakalpakstan, despite the decline. Incidence is likely to be strongly related to factors associated with region of residence and with ethnicity.

Adolescent↗
PubMed1992

Further evidence of benefits of a (non-randomised) breast cancer screening programme: the DOM project.

STUDY OBJECTIVE: The aim was to demonstrate the benefits of breast cancer screening on mortality. DESIGN: The study was an evaluation of a breast cancer screening programme by means of different approaches: (1) a case-control study, breast cancer deaths being the cases; (2) comparing the numbers of breast cancer deaths in screened and unscreened women; (3) comparing breast cancer mortality before and after start of the programme; (4) comparing breast cancer mortality in different large cities; (5) comparing screening activity with mortality reduction. SETTING: The setting was a breast cancer screening programme in the city of Utrecht, the DOM project, for women aged 50-64 years old at intake, birth cohort 1911-1925. The programme started in 1974, and there were five screening rounds up to 1984. Participation rate in the first round was 72% (14,697 women). MAIN RESULTS: (1) Screening was protective against dying from breast cancer, odds ratio 0.52, with a stronger effect in older women and no evidence of confounding; (2) risk ratio of dying from breast cancer for women in the response group was the same as the odds ratio, 0.52; (3) breast cancer death rate after the start of the project was nearly 20% lower than before the project started; after correcting for women who could not have benefited from screening the reduction was 33%; (4) a rise in breast cancer mortality in birth cohort 1911-1925 seen in other large cities without a screening programme due to aging of the cohort was not seen in the city of Utrecht; (5) mortality reduction followed the screening activity with a time lag of approximately 5 years. CONCLUSIONS: Early diagnosis of breast cancer by mammography reduces breast cancer mortality in women 50-64 years old at intake; different approaches to the evaluation of the project give different estimates of the screening effect, making clear that the effect depends on the intensity of the programme.

Breast Neoplasms↗
PubMed1992

External validation, repeat determination, and precision of risk estimation in misclassified exposure data in epidemiology.

STUDY OBJECTIVE: The aim was to quantify the difference in precision of risk estimates in epidemiology between the situations where misclassification of exposure is corrected for by external validation and where it is corrected for by internal repeat measurement. Precision was measured in terms of the expected width of the 95% confidence interval on the odds ratio. DESIGN: In a hypothetical case-control study, first with 100 cases and 100 controls, then with 100 cases and 1000 controls (the latter to approximate the cohort study situation), expected estimated odds ratios and confidence intervals were calculated based on postulated underlying true odds ratios and misclassification error rates. The sizes of the confidence intervals using the two design strategies were compared, based on the same number of subjects receiving internal repeat measurements as were used in the external validation study. MAIN RESULTS: Confidence intervals obtained using internal repeat measurement were considerably narrower than those using external validation. Both methods yielded approximately correct point estimates. CONCLUSIONS: In terms of precision, it is preferable to correct for misclassification using internal repeat measurement rather than external validation.

Analysis of Variance↗
PubMed1992

Screening for cervical cancer: is there a place for incorporating tests for the human papillomavirus?

Well organized screening programmes for cervical cancer, based on exfoliative cervical cytology, are known to be effective at reducing the incidence of invasive cervical cancer and mortality from the disease. HPV testing should not replace cervical cytology as the first-line approach in screening for cervical cancer, as HPV testing is not sufficiently reliable and some cancers are not associated with HPV infection. Even though there are many unanswered questions about the validity of HPV tests, it is timely to consider whether HPV testing might improve the management of the substantial number of women whose smears are neither clearly normal nor abnormal, but are described as atypical, suspicious or mildly dyskaryotic. The efficacy and costs of incorporating HPV testing into a cervical cancer screening programme need to be evaluated in controlled trials.

Female↗
PubMed1992

Use of external rates in nested case-control studies with application to the international radiation study of cervical cancer patients.

A method is proposed for analysis of nested case-control studies that combines the matched comparison of covariate values between cases and controls and a comparison of the observed numbers of cases in the nesting cohort with expected numbers based on external rates and average relative risks estimated from the controls. The former comparison is based on the conditional likelihood for matched case-control studies and the latter on the unconditional likelihood for Poisson regression. It is shown that the two likelihoods are orthogonal and that their product is an estimator of the full survival likelihood that would have been obtained on the total cohort, had complete covariate data been available. Parameter estimation and significance tests follow in the usual way by maximizing this product likelihood. The method is illustrated using data on leukemia following irradiation for cervical cancer. In this study, the original cohort study showed a clear excess of leukemia in the first 15 years after exposure, but it was not feasible to obtain dose estimates on the entire cohort. However, the subsequent nested case-control study failed to demonstrate significant differences between alternative dose-response relations and effects of time-related modifiers. The combined analysis allows much clearer discrimination between alternative dose-time-response models.

Case-Control Studies↗