ECHOGRAPHIE ET DEPISTAGE DU CANCER DU SEIN

ECHOGRAPHIE ET DEPISTAGE DU CANCER DU SEIN
QUESTION : L’échographie des seins est-elle une solution de rechange pour le
dépistage du cancer du sein chez les femmes de plus de 50 ans qui refusent la
mammographie à cause de l’inconfort que celle-ci entraîne?
AUTEUR : Nina Paradis-Robert
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femmes de plus de 50 ans refusant la mammographie, en situation de
dépistage général
échographie des seins
examen des seins et/ou mammographie
idéalement une diminution de la mortalité par cancer du sein, sinon les
valeurs de sensibilité et de spécificité comparativement à la
mammographie
CONTEXTE : Plus d’une femme dans ma pratique sont inquiètes face au cancer du
sein, mais elles refusent la mammographie car elles ont eu de la douleur lors d’un
examen précédent.
RECHERCHE :
Avec les mots : breast, cancer, screening, ultrasound, sonography, ultrasonography, et
différentes combinaisons de ceux-ci.
Dans Cochrane, plusieurs études sont trouvées, mais aucune ne porte sur l’échographie
comme moyen de dépistage.
Des recherches sur Bandolier, Clinical Evidence, Best Bets, Trip Database et Pubmed
ont aussi donné peu de résultats. J’ai quand même sélectionné trois articles:
RESULTATS:
1) JG Elmore, K Armstrong, CD Lehman, SW Fletcher.Screening for Breast Cancer
Cinical Review. JAMA 2005 March 9. 293 (10).
Context: Breast cancer screening in community practices may be different from that in
randomized controlled trials. New screening modalities are becoming available.
Objectives: To review breast cancer screening, especially in the community and to
examine evidence about new screening modalities.
Data Sources and Study Selection: English language articles of randomized controlled
trials, assessing effectiveness of breast cancer screening were reviewed, as well as
meta-analyses, systematic reviews, studies of breast cancer screening in the
community, and guidelines. Also, studies of newer screening modalities were assessed.
Data synthesis: […] Magnetic resonance imaging and ultrasound are being studied for
screening women at high risk for breast cancer but are not recommended for screening
the general population. […] Breast ultrasound data are available from diagnostic
populations, with screening studies limited to women with dense breasts on
mammography or at increased risk for breast cancer. Although ultrasound may detect 3
to 4 additional breast cancers per 1000 women in these increased-risk populations,
there are no data on the use of screening ultrasound in the general population. […]
Preliminary data [provenant d’études portant sur des femmes à risque élevé de cancer
du sein ou des femmes aux seins denses] suggest a higher rate of false positive
examination results with ultrasound than with mammography alone.
Conclusions : In the community, mammography remains the main screening tool while
effectiveness of clinical breast examination and self examination are less. New
screening modalities are unlikely to replace mammography in the near future for
screening the general population.
2) LSJ Sim, JHCL Henricks, SMC Fook-Chong. Breast Ultrasound in Women With
Familial Risk of breast Cancer. Ann Acad Med Singapore 2004;33:600.
Introduction: The aim of this study was to assess the performance and value of breast
ultrasound in women with familial risk of breast cancer.
Materials and Methods: From an initial dataset of 245 women with positive family history
who had breast cancer surveillance utilizing mammography or magnetic resonance
imaging (MRI) between November 1994 and February 2001, 179 subjects with follow-up
data were selected. Eighty-four women had breast ultrasound done with
histopathological correlation available from 48 breast biopsies performed in 42 women.
Results: The sensitivity of ultrasound, mammography and MRI was 83.3%, 53.9% and
93.3%, respectively. Ultrasound was the imaging modality with intermediate sensitivity,
specificity, negative predictive value (NPV) and cancer detection rate. […]
[La spécificité de l’échographie et de la mammographie étaient respectivement de 65.5
et 85.7; Les VPP, en respectant le même ordre, 50 et 63.3 et les VPN 90.5 et 80.]
Conclusions: Although breast ultrasound screening per se was not assessed in this
study, extrapolation of these results to sonographic screening of high familial risk
women would come at a better specificity to MRI, albeit with a 10% decrease in
sensitivity but a fraction of the cost of MRI. Ultrasound also provides the advantage of
convenient imaging guidance for biopsy. Employing ultrasound following mammography
would match MRI in sensitivity, specificity, PPV, NPV and accuracy, and should not be
ignored in these women.
3) P Crystal, SD Starno, S Shcharynski, MJ Koretz. Using Sonography to Screen
Women with Mammographically Dense Breasts. AJR, July 2003
Objectives: Mammographicaly dense breast tissue has been reported both as a cause
of false-negative findings on mammography and as an indicator of increased breast
cancer risk. We conducted this study to evaluate the role of breast sonography as a
second-line screening test in women with mammographicaly dense breast tissue.
Materials and Methods: Between January 2000 and January 2002, 1517 asymptomatic
women with dense breasts and normal mammography and physical examination
findings underwent physician-performed breast sonography as an adjunct screening
test. Within the study group, 318 women had a first-degree family history or a personal
history of breast cancer. The high-risk subgroup comprised these women.
The detection rate of breast cancer in this subgroup was compared with the detection
rate in the remaining study population with baseline risk.
Results: Of 1517 women examined, seven breast cancers were diagnosed (cancerdetection rate, 0.46%). Four carcinomas were detected in high-risk women and three in
women with baseline risk. The cancer-detection rate in the subgroup of high-risk women
was 1.3%, significantly higher (p<0.04) than the cancer-detection rate of 0.25% in the
baseline risk subgroup. All cancers were T1 (range, 4-12 mm; mean, 9.6 mm). Sentinel
lymph nodes were negative for cancer in six of seven carcinomas.
Conclusion: Screening breast sonography in the population of women with dense breast
tissue is useful in detecting small breast cancers that are not detected on
mammography or clinical examination. The use of sonography as an adjunct to
screening mammography in women with increased risk of breast cancer and dense
breasts may be especially benefical.
CONCLUSION :
Je n’ai pas trouvé d’étude concernant l’échographie des seins en situation de dépistage
dans la communauté, pas plus que les auteurs du premier article cité n’en avaient
identifié. Le deuxième article montre que la VPP de l’échographie serait inférieur à la
VPP de la mammographie dans une population où la prévalence de cancer du sein est
supposément plus élevée. Ceci m’amène à demander : la VPP de l’échographie du sein
est-elle acceptable en situation de dépistage de la population? Ce type de dépistage
entraînerait-il un trop gros fardeau pour les patientes (plus d’anxiété non fondée, plus de
biopsies et leurs complications pour des résultats normaux) ou pour le système de santé
québécois (augmentation des coûts de dépistage et augmentation des besoins
matériels et de ressources humaines)?
En absence de données, je ne peux donc pas recommander l’échographie pour le
dépistage du cancer du sein. Mon intervention auprès de ces patientes se résumera
donc, pour le moment, à une revue des points positifs et négatifs concernant la
mammographie.