samedi 7 janvier 2012

Cancer de la prostate: le dépistage par le PSA est il utile?

"Mortality was 3.7 and 3.4 per 10,000 with and without screening, respectively, a nonsignificant difference."
A vous de juger.

http://www.medpagetoday.com/HematologyOncology/ProstateCancer/30548?utm_medium=email&utm_campaign=DailyHeadlines&utm_source=WC&email=guyandrepelouze@gmail.com&eun=g432148d0r&userid=432148&mu_id=5529932

3 commentaires:

hippocrate a dit…

Les basses statistiques sont devenues l'art scientifique du mensonge, au service du grand "tout" normalisateur.

"Les lois des grands nombres sont vraies pour les grands nombres" ( en mécanique statistique, sachant que les atomes et molécules ne sont pas soumis aux variations interindividuelles, un 'grand nombre" est d'un ordre de grandeur supérieur à 1000 milliards.)

".....et sont fausses pour les petits nombres".
Un patient, c'est un grand ou un petit nombre?

l'evidence based medicine est une supercherie.

Le pb de l'attitude thérapeutique face à un cancer détecté serait grandement résolu si l'on disposait de critères d'évolutivité ( biologie, histologie )...ce n'est pas encore le cas

.....

THEGAP a dit…

Avez vous seulement lu l'abstract de l'article?
La question posée n'est pas celle de l'attitude thérapeutique face à un cancer certain mais la question de savoir si le dépistage par le PSA améliore la survie.
La réponse à cette question est manifestement non dans cette cohorte.
Les statistiques servent à rejeter l'hypothèse nulle.
La définition d'un grand nombre n'est pas tout à fait celle que vous décrivez ce qui compte c'est le niveau d'erreur admis. Si vous admettez de vous tromper dans 5% des cas alors vous pouvez affirmer que le dépistage par le PSA n'améliore pas la survie. Si vous voulez une plus grande probabilité de ne pas vous tromper il faut dimensionner un plus grand nombre de patients dans l'étude.
Dire que l'EBM est une supercherie est une autre affirmation sans preuve. Sans l'EBM nous serions toujours en train de faire confiance à des impressions, des des biais voire des tromperies manifestes. Ce qui a été le cas de médecine depuis longtemps; mais il ya une autre conséquence économique celle là, les ressources étant rares et le système de soins financé par une ressource d'impôt il convient au moins de ne pas jeter l'argent en pure perte...

THEGAP a dit…

Abstract:Prostate Cancer Screening in the Randomized Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial: Mortality Results after 13 Years of Follow-up





Abstract

Background The prostate component of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial was undertaken to determine whether there is a reduction in prostate cancer mortality from screening using serum prostate-specific antigen (PSA) testing and digital rectal examination (DRE). Mortality after 7–10 years of follow-up has been reported previously. We report extended follow-up to 13 years after the trial.

Methods A total of 76 685 men, aged 55–74 years, were enrolled at 10 screening centers between November 1993 and July 2001 and randomly assigned to the intervention (organized screening of annual PSA testing for 6 years and annual DRE for 4 years; 38 340 men) and control (usual care, which sometimes included opportunistic screening; 38 345 men) arms. Screening was completed in October 2006. All incident prostate cancers and deaths from prostate cancer through 13 years of follow-up or through December 31, 2009, were ascertained. Relative risks (RRs) were estimated as the ratio of observed rates in the intervention and control arms, and 95% confidence intervals (CIs) were calculated assuming a Poisson distribution for the number of events. Poisson regression modeling was used to examine the interactions with respect to prostate cancer mortality between trial arm and age, comorbidity status, and pretrial PSA testing. All statistical tests were two-sided.

Results Approximately 92% of the study participants were followed to 10 years and 57% to 13 years. At 13 years, 4250 participants had been diagnosed with prostate cancer in the intervention arm compared with 3815 in the control arm. Cumulative incidence rates for prostate cancer in the intervention and control arms were 108.4 and 97.1 per 10 000 person-years, respectively, resulting in a relative increase of 12% in the intervention arm (RR = 1.12, 95% CI = 1.07 to 1.17). After 13 years of follow-up, the cumulative mortality rates from prostate cancer in the intervention and control arms were 3.7 and 3.4 deaths per 10 000 person-years, respectively, resulting in a non-statistically significant difference between the two arms (RR = 1.09, 95% CI = 0.87 to 1.36). No statistically significant interactions with respect to prostate cancer mortality were observed between trial arm and age (Pinteraction = .81), pretrial PSA testing (Pinteraction = .52), and comorbidity (Pinteraction = .68).

Conclusions After 13 years of follow-up, there was no evidence of a mortality benefit for organized annual screening in the PLCO trial compared with opportunistic screening, which forms part of usual care, and there was no apparent interaction with age, baseline comorbidity, or pretrial PSA testing.

 
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