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Biomedical subjects

J Estève

Publications and source records attributed to J Estève.

At least 19 recordsLinked to original sources
PubMed2007

An overall strategy based on regression models to estimate relative survival and model the effects of prognostic factors in cancer survival studies.

Relative survival provides a measure of the proportion of patients dying from the disease under study without requiring the knowledge of the cause of death. We propose an overall strategy based on regression models to estimate the relative survival and model the effects of potential prognostic factors. The baseline hazard was modelled until 10 years follow-up using parametric continuous functions. Six models including cubic regression splines were considered and the Akaike Information Criterion was used to select the final model. This approach yielded smooth and reliable estimates of mortality hazard and allowed us to deal with sparse data taking into account all the available information. Splines were also used to model simultaneously non-linear effects of continuous covariates and time-dependent hazard ratios. This led to a graphical representation of the hazard ratio that can be useful for clinical interpretation. Estimates of these models were obtained by likelihood maximization. We showed that these estimates could be also obtained using standard algorithms for Poisson regression.

Aged↗
PubMed2006

Survival of cancer patients in France: a population-based study from The Association of the French Cancer Registries (FRANCIM).

We present the main results of the first population-based cancers survival study gathering all French registry data. Survival data on 205,562 cancer cases diagnosed between 01/01/1989 and 31/12/1997 were analysed. Relative survival was estimated using an excess rate model. The evolution of the excess mortality rate over the follow-up period was graphed. The analysis emphasised the effect of age at diagnosis and its variation with time after diagnosis. For breast and prostate cancers, the age-standardised five-year relative survivals were 84% and 77%, respectively. The corresponding results in men and women were 56% versus 58% for colorectal cancer and 12% versus 16% for lung cancer. For some cancer sites, the excess mortality rate decreased to low values by five years after diagnosis. For most cancer sites, age at diagnosis was a negative prognostic factor but this effect was often limited to the first year after diagnosis.

Adolescent↗
PubMed2004

Trends and socioeconomic inequalities in cancer survival in England and Wales up to 2001.

We examined national trends and socioeconomic inequalities in cancer survival in England and Wales during the 1990s, using population-based data on 2.2 million patients who were diagnosed with one of the 20 most common cancers between 1986 and 1999 and followed up to 2001. Patients were assigned to one of five deprivation categories (from 'affluent' to 'deprived') using characteristics of their electoral ward of residence at diagnosis. We estimated relative survival up to 5 years after diagnosis, adjusting separately in each deprivation category for background mortality by age, sex and calendar period. We estimated trends in survival and in the difference in survival between deprivation categories ('deprivation gap') over the periods 1986-90, 1991-95 and 1996-99. We used period analysis to examine likely survival rates in the near future. Survival improved for most cancers in both sexes during the 1990s, and appears likely to continue improving for most cancers in the near future. The deprivation gap in survival between rich and poor was wider for patients diagnosed in the late 1990s than in the late 1980s. Increases in cancer survival in England and Wales during the 1990s are shown to be significantly associated with a widening deprivation gap in survival.

England↗
PubMed2003

Does hormone replacement therapy increase the frequency of breast atypical hyperplasia in postmenopausal women? Results from the Bouches du Rhone district screening campaign.

It is thought that the risk of atypical hyperplasia (AH) increases with age, particularly among postmenopausal women. Three hypotheses were investigated to try to explain this phenomena: use of hormone replacement therapy (HRT), increased breast cancer screening and improvements in radiological quality. Data were collected from the Bouches du Rhône breast cancer screening programme database and from the pathological registry of all women operated on for breast diseases in the district. The AH incidence rate was studied using a Poisson regression analysis. The change in the profile of breast diseases was explored through studying changes in the proportion of AH among benign lesions and malignant diseases. The AH incidence rate significantly increased over time (13.6% per year). The proportion of AH among the benign diseases increased with time and was significantly higher for HRT users (Odds Ratio (OR)=2.05; 95% Confidence Interval (CI): 1.43-2.93). While AH decreased with age among HRT non-users, it increased among users as a proportion of both benign and malignant lesions. The AH incidence rate significantly increased among pre- and postmenopausal women. Our study suggests that this increase is partly explained by the incidental discovery of these lesions by mammography and partly by a real increase of the disease among HRT users.

Aged↗
PubMed2003

Keeping data continuous when analyzing the prognostic impact of a tumor marker: an example with cathepsin D in breast cancer.

The prognostic value of cathepsin D has been recently recognized, but as many quantitative tumor markers, its clinical use remains unclear partly because of methodological issues in defining cut-off values. Guidelines have been proposed for analyzing quantitative prognostic factors, underlining the need for keeping data continuous, instead of categorizing them. Flexible approaches, parametric and non-parametric, have been proposed in order to improve the knowledge of the functional form relating a continuous factor to the risk. We studied the prognostic value of cathepsin D in a retrospective hospital cohort of 771 patients with breast cancer, and focused our overall survival analysis, based on the Cox regression, on two flexible approaches: smoothing splines and fractional polynomials. We also determined a cut-off value from the maximum likelihood estimate of a threshold model. These different approaches complemented each other for (1) identifying the functional form relating cathepsin D to the risk, and obtaining a cut-off value and (2) optimizing the adjustment for complex covariate like age at diagnosis in the final multivariate Cox model. We found a significant increase in the death rate, reaching 70% with a doubling of the level of cathepsin D, after the threshold of 37.5 pmol mg(-1). The proper prognostic impact of this marker could be confirmed and a methodology providing appropriate ways to use markers in clinical practice was proposed.

Aged↗
PubMed2003

Cancer incidence and mortality in France over the period 1978-2000.

BACKGROUND: Monitoring cancer incidence and mortality time trends is essential for cancer research and health-care planning. French cancer registries do not cover the entire population and do not provide a representative sample of the national population. Our study aimed at estimating national cancer incidence and mortality trends over the longest period available. METHODS: Incidence and mortality data were collected over the period 1978-1997. Twenty-seven cancer sites were selected and age, sex and site specific incidence and mortality rates were estimated for each year from 1978 up to 2000. Observed incidence and mortality data in the population covered by cancer registries were modelled using age-cohort methods. An estimation of the incidence/mortality ratio was obtained from these models and applied to the mortality rates predicted from an age-cohort model for the entire French population. The person-years of observation were calculated cohort-wise from census data provided by the national institute of statistics RESULTS: Cancer incidence increased by 63% throughout the study period, from 170,000 new cases in 1980 to 278,000 in 2000. This evolution was due to demographic changes but also to an increase in the risk of cancer which was estimated to more than 35% during the same period. In men, this change is largely explain by the increase of prostate cancer incidence. Among women, the increase was dominated by the continuing increase in breast cancer incidence. Large increases were also seen for non-Hodgkin lymphoma, melanoma, and thyroid cancer in both genders and for lung cancer in women. Cancer mortality increased by 20% from 125,000 deaths in 1980 to 150,000 in 2000. This increase is less than that predicted from changes in demographic factors and corresponds in fact to a decrease in the risk of death estimated to about 8%, slightly greater for women than for men. This decrease is associated with a decreasing incidence for stomach cancers for both sexes, alcohol-related cancer for men and cervical cancer for women. Colo-rectal cancer decreasing mortality contributes to this improvement despite an incidence increase. CONCLUSION: Between 1980 and 2000, the study showed a large change in the cancer burden both quantitatively and qualitatively. Decrease in exposure, earlier diagnosis and therapeutic improvement explained part of this change, but overall the distribution of cancer cases shifted toward a distribution including less aggressive cancers. A striking divergence between incidence and mortality trends is observed for a great number of cancers. Prostate cancer shares with breast cancer the same pattern of a severe increasing incidence and a stable mortality. This points to important changes in medical practice and needs further analysis. The trend of lung cancer mortality among women should be emphasised since the situation will inevitably worsen in the coming years. It is already the third cause of cancer death among women.

Age Distribution↗
PubMed2002

Specular reflection of matter waves from a rough mirror.

We present a high resolution study of the specularity of the atomic reflection from an evanescent wave mirror using velocity selective Raman transitions. We observed a double structure in the velocity distribution after reflection: a peak consistent with specular reflection and a diffuse reflection pedestal whose contribution decreases rapidly with increasing detuning. The diffuse reflection is due to two distinct effects: spontaneous emission in the evanescent wave and roughness in the evanescent wave potential whose amplitude is smaller than the de Broglie wavelength of the reflected atoms.

Journal Article↗
PubMed2002

Does a better grade of tumour occurring in women under hormone replacement therapy compensate for their lower probability of detection by screening mammography.

OBJECTIVE: To compare the prognostic factor of breast cancer survival between breast cancer diagnosed in subjects receiving hormone replacement therapy (HRT) before diagnosis to those without such a therapy. SUBJECTS AND METHODS: All breast cancers diagnosed between 1993 and 2000 within the breast cancer screening programme in Bouches du Rhône (France) were analysed for size, node status, and grade according to use, or not, of HRT. Univariate and multivariate analyses were carried out taking into account age, density of the breast, and mode of detection. RESULTS: The breast tumours diagnosed among HRT users had a lower grade whatever the mode of detection. The proportion of node positive tumours was identical in the two groups after adjustment for age. The smaller size of the tumours among HRT users is partly explained by the lower grade of these tumours Conclusion: Although tumours occurring in HRT users have a lower chance of being detected by screening, their prognostic factors, especially the grade of the tumour, are better than in non-users. More work is needed to find which part of this advantage is attributable to better surveillance of women treated with HRT

Aged↗
PubMed2002

[How to choose in practice a model to describe the geographic variation of cancer incidence? Example of gastrointestinal cancers from Côte-d'Or].

BACKGROUNDS: In epidemiology, standardized Incidence Ratio (SIR) can have large variance and it is then difficult to distinguish random fluctuations from real spatial variations when describing spatial variations in the rate of cancer. In this context, hierarchical model produce smoothed relative risks estimations helpful for solving this problem. The main advantage of these methods is to combine information of each geographical area with that obtained from prior assumption on the similarity between geographical sub-units. Nevertheless different assumptions produce different geographical maps of incidence of cancer, and the purpose of the present study was the development of a strategy to choose the most satisfactory description of the incidence of digestive cancer in a French department. METHODS: The strategy to choose the most satisfactory geographical map depends on the following criteria: variability between geographical sub-units, auto-correlation, and variability within geographical sub-unit. These criteria have been estimated from observed data for each site of cancer. RESULTS: This strategy was applied to digestive tract cancers diagnosed between 1976 and 1997 in the department of Côte-d'Or, France. High-risk areas were often detected in the urban zone of the department, but without autocorrelation in most cases. CONCLUSION: This strategy permitted to describe cancers in very small areas, avoiding to a large extent the danger of focusing on falsely positive high-risk areas.

Algorithms↗
PubMed2001

Maternity hospitals ranking on prophylactic caesarean section rates: uncertainty associated with ranks.

OBJECTIVE: Ranking maternity hospitals on prophylactic caesarean section rates. STUDY DESIGN: The study population was a sample of 8470 women having delivered in the 86 maternity hospitals of the Rhône-Alpes region (France) in 1990. A two-level logistic model and the Gibbs sampling method were used to estimate the adjusted rate and rank of each maternity hospital with their 95% credible interval. RESULTS: Ranking of maternity hospitals was substantially modified after adjusting for differences in case-mix. The 95% credible intervals of the ranks were generally wide and overlapping. No maternity hospital could be confidently placed in the upper quarter nor in the lower quarter of the league table. CONCLUSION: The use of ranks based on rates to compare hospitals may be seriously misleading; thus, league tables need an accompanying reading guide. Furthermore, some rules should be respected, including the need to make accurate case-mix adjustments, to reduce the rate instability in smaller hospitals, and to highlight the uncertainty associated with ranks.

Cesarean Section↗
PubMed2001

Projecting cancer incidence and mortality using Bayesian age-period-cohort models.

BACKGROUND: We present a practical application of an age-period-cohort model in a Bayesian frame-work for making cancer-burden projections. METHODS: Second degree autoregressive smoothing was used on the age, period and cohort effects for estimating future incidence and mortality. RESULTS: We are able to demonstrate the feasibility, flexibility and strengths of this approach. Compared with previously used methods, it performed better for providing point estimates when past trends continued into the future. However, the extremely wide credible intervals need careful interpretation. DISCUSSION: Part of the uncertainty is attributable to the possible inadequacy of the model and not necessarily relevant in the prediction of what would happen if the present trends continue into the future.

Age Factors↗
PubMed2000

Methodological questions in sentinel lymph node analysis in breast cancer patients.

BACKGROUND: The sentinel lymph node (SLN) procedure has been proposed to women with breast cancer with clinically negative axillary lymph nodes, in order to avoid conventional axillary lymph node dissection and its associated side-effects. Methodological aspects of the validation of the SLN procedure are questioned here. MATERIALS AND METHODS: The results of relevant published studies are reviewed, with emphasis on pathological techniques. The ability of the SLN procedure to diagnose lymph node metastases, the extent to which axillary lymph node dissection contributes to treatment, apart from identification of the stage, and the effect of a modified staging procedure on treatment strategies are analyzed. RESULTS AND CONCLUSION: Both the sensitivity and the negative predictive value of the SLN procedure are overestimated if the probability of missing lymph node metastases is not taken into account, even when a complete axillary dissection is performed as a control. The SLN strategy and its effects on staging and treatment cannot be evaluated by comparison with conventional axillary lymph node dissection in a one-arm study but require carefully designed randomized trials.

Algorithms↗
PubMed2000

Analysing the difference due to risk and demographic factors for incidence or mortality.

BACKGROUND: From an epidemiological and public health perspective there is an interest in quantifying differences in incidence and mortality between either time points, geographical areas or males and females. We propose a method for splitting such a difference in the number of cases/deaths into three components: (1) those due to risk; (2) those due to population structure (i.e. age distribution); and (3) those due to population size. We also propose graphical methods for presenting the results. Three examples are used to illustrate our methodology.

Adolescent↗
PubMed1999

Hormone replacement therapy and screening mammography: analysis of the results in the Bouches du Rhône programme.

OBJECTIVE: To evaluate the effectiveness of a mass screening programme for breast cancer in a French population where hormone replacement therapy (HRT) is common and where mammography is prescribed outside the programme for asymptomatic women. METHODS: From 1993 to 1996 inclusive, 41,062 women underwent a first test and 48,275 a second or third test in the Bouches du Rhône programme. Their HRT status was ascertained at the time of the test. False positive and false negative tests were identified at one year follow up. The incidence of interval cancers was estimated up to three years after the screening test. RESULTS: The odds of being detected at screening rather than as an interval cancer within one year of the test was five times greater among non-users of HRT than among users (odds ratio (OR) 5.14 (confidence interval 2.5 to 11.8)). This high reduction in sensitivity among users (71% v 92%) was associated with a very small reduction in specificity at the incident screen only. The incidence of interval cancers among HRT users was 3.5 times that of non-users within the first year after the test and 1.7 times during the following two years. CONCLUSIONS: When the early results of a programme have been used to measure its effectiveness they should be reassessed in populations where HRT is in widespread use. As interval cancers had better prognostic factors in HRT users than in non-users, the efficacy of a screening programme in such populations should be the subject of further studies.

Aged↗
PubMed1998

Survival of women with breast cancer in Europe: variation with age, year of diagnosis and country. The EUROCARE Working Group.

Breast cancer is the most frequent malignancy among women in developed countries. Prognosis is better than for other major cancers, and an improvement in survival has been reported for several populations in recent decades. Within the framework of EUROCARE, a population-based project concerned with the survival and care of cancer patients in Europe, we analysed data from 119,139 women diagnosed with breast cancer between 1978 and 1985 in 12 countries and followed for at least 6 years. Multiple regression models of relative survival, which take mortality from all other causes in each area into account, were used to estimate the effect of age, period of diagnosis and country on survival. For the comparison between countries, survival rates were age-standardised to the age structure of the entire study population. Women aged 40-49 years at diagnosis had the best prognosis in all countries and throughout the study period. Women younger than 30 years at diagnosis had a worse prognosis than those aged 30-39. The highest relative survival at 5 years was in Finland and Switzerland (about 74%), intermediate levels were found for Italy, France, The Netherlands, Denmark and Germany (about 70%) and the lowest rates were in Spain, the United Kingdom, Estonia and Poland (55-64%). During the 6 months following diagnosis, survival was highly dependent on age and was sharply lower in women older than 49 years. For women surviving more than 6 months after diagnosis, survival was similar for all ages, although women aged 40-49 still had the better prognosis. The average rate of death from breast cancer fell by about 2.5% for each year of diagnosis between 1978 and 1985. This improvement manifested mainly in younger and older women, for whom survival was initially less good. The largest improvement was seen in Poland (-15% death risk per year). We suggest that the better survival of women aged 40-49 at diagnosis is related to lower levels of circulating sex hormones, resulting in reduced stimulation of tumour cell growth. Early diagnosis may also be important in the peri-menopausal period due to increased diagnostic attention. Low survival in the United Kingdom may be due to inadequate adherence to consensus treatment guidelines and greater variation in treatment.

Adult↗
PubMed1998

Neuroblastoma in Europe: differences in the pattern of disease in the UK. SENSE. Study group for the Evaluation of Neuroblastoma Screening in Europe.

BACKGROUND: Neuroblastoma is a major contributor to childhood cancer mortality, but its prognosis varies with age and stage of disease, and some tumours regress spontaneously. Urinary screening programmes or clinical examination may detect the disease before symptoms appear, but the benefit of early diagnosis is uncertain. We examined the incidence, pattern, and presentation of neuroblastoma in four European countries. METHOD: Population-based incidence rates were derived for France, Austria, Germany, and the UK. Age, sex, and stage distribution were analysed by Mantel-Haenszel techniques and Poisson regression. The proportion of incidental diagnoses (cases without symptoms found at routine health checks or during investigation of other disorders) and mortality rates were also compared. FINDINGS: Between 1987 and 1991, 1672 cases of neuroblastoma were diagnosed in children under 15 years old (France, 624; Austria, 69; Germany, 493; UK, 486). Age-standardised annual incidence was significantly lower in the UK (10.1/million) than in France (12.5) and Germany (11.4). In the UK a deficit of low-stage disease in infants was accompanied by an excess of stage IV in older children. The UK had significantly fewer incidental diagnoses (8%) than Austria (27%) and Germany (34%). UK mortality rates were significantly higher than German or French rates. INTERPRETATION: In the UK, neuroblastoma diagnosis is delayed, possibly because of a less rigorous system of health checks for children. Although some overdiagnosis occurs in mainland Europe, our data suggest that in the UK some low-stage cases, undetected in infancy, may later present as advanced disease. This finding has implications for screening programmes and organisation of routine surveillance of infant health in the UK.

Adolescent↗