12 februari 2013: Bron: CMAJ - Canadian Medical Association Journal.

Wie veel soja - isoflavonen eet aanvullend op hormoontherapie voorkomt vaker een recidief bij hormoongevoelige borstkanker dan alleen hormoontherapie en weinig eten van soja - isoflavonen.
Dit blijkt uit een 5 jarige studie bij 524 vrouwen die succesvol geopereerd konden worden aan hun borstkanker en postoperatief een endocriene behandeling (hormoontherapie) kregen. De studie werd uitgevoerd aan de Harbin Medical University in Harbin, China.

De onderzoekers onderzochten de relatie tussen de inname van soja - isoflavonen en sterftekansen of kans op een recidief van borstkanker bij 524 patiënten die geopereerd waren voor borstkanker tussen augustus 2002 en juli 2003 en die post operatief werden behandeld met een hormoontherapie - endocriene behandeling van arimidex - anastrozole. Bij de start van de studie werd de inname van soja - isoflavonen gemeten met een zogeheten gevalideerde voedsel frequentie vragenlijst. De follow-up van de studie duurde totaal 5,1 jaar

Voor de totale sterfte (30,6%) bij premenopauzale patiënten (voor de overgang) werd geen relatie gevonden voor soja - isoflavonen inname (HR, 1,05, 95% CI, 0,78 tot 1,71 voor het hoogste kwartiel
[> 42,3 mg / dag] versus het laagste kwartiel [<15,2 mg / dag ], P voor trend = 0,87). Bij postmenopauzale patiënten (na de overgang), hadden de vrouwen die in het hoogste kwartiel van soja-isoflavonen inname zaten een significant lager risico op een recidief versus die in het laagste kwartiel (HR, 0,67, 95% CI, 0,54 tot 0,85; P voor trend = .02). Er werd echter geen effect op overall overleving waargenomen. Bij patiënten met oestrogeen en progesteron receptor positieve ziekte en degenen die arimidex - anastrozol hadden gebruikt bleek het effect het grootst te zijn. De kans op een recidief van oestrogeen en progesteron positieve borstkanker was 12,9% lager bij patiënten in het hoogste kwartiel van soja - isoflavonen inname dan bij degenen in het laagste kwartiel en was 18,7% lager voor patiënten in het hoogste kwartiel die ook arimidex - anastrozol gebruikten.

Beperkingen van deze studie zijn dat ook andere bioactieve componenten in soja, zoals soja eiwit, borstweefsel kan beïnvloeden en daardoor niet zomaar als veralgemening op andere populaties met veel
lagere sojaconsumptie worden toegepast. Bovendien werden biologische monsters zoals bloed of urine voor de bepaling van soja niveaus niet verzameld. Aldus de onderzoekers.

Echter zij concluderen dat de resultaten uit hun studie potentieel belangrijk is in termen van aanbevelingen voor de inname van soja - isoflavonen in combinatie met hormoontherapie - endocriene therapie, Al pleiten zij ook voor grote multicentrische klinische studies en andere observationele epidemiologische studies om deze bevindingen te bevestigen.

U kunt het volledige studierapport: Effect of soy isoflavones on breast cancer recurrence and death for patients receiving adjuvant endocrine therapy gratis inzien. Hier het abstract van de studie:

High dietary intake of soy isoflavones was associated with lower risk of recurrence among post-menopausal patients with breast cancer positive for estrogen and progesterone receptor and those who were receiving anastrozole as endocrine therapy.

CMAJ. 2010 November 23; 182(17): 1857–1862.

doi: 10.1503/cmaj.091298

PMCID: PMC2988534

Effect of soy isoflavones on breast cancer recurrence and death for patients receiving adjuvant endocrine therapy

Xinmei Kang, MD PhD, Qingyuan Zhang, MD PhD, Shuhuai Wang, MD, Xu Huang, MD, and Shi Jin, MD

Abstract

Background

The intake of soy isoflavones among women with breast cancer has become a public health concern, because these compounds have weak estrogenic effects. There is little clinical evidence about their safety for patients with breast cancer who are receiving adjuvant endocrine therapy.

Methods

For patients who underwent surgery for breast cancer between August 2002 and July 2003 and who were receiving adjuvant endocrine therapy, we examined associations between dietary intake of soy isoflavones and recurrence of breast cancer and death. We measured dietary intake of soy isoflavones at baseline using a validated food frequency questionnaire. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) by means of multivariable Cox proportional hazards regression models. We further stratified the analyses by hormonal receptor status and endocrine therapy.

Results

The median follow-up period for the 524 patients in this study was 5.1 years. Among premenopausal patients, the overall death rate (30.6%) was not related to intake of soy isoflavones (HR = 1.05, 95% CI 0.78–1.71 for the highest quartile [> 42.3 mg/day] v. the lowest quartile [< 15.2 mg/day], p for trend = 0.87). Relative to post-menopausal patients in the lowest quartile of soy isoflavone intake, the risk of recurrence for post-menopausal patients in the highest quartile was significantly lower (HR = 0.67, 95% CI 0.54–0.85, p for trend = 0.02). Inverse associations were observed in patients with estrogen and progesterone receptor positive disease and those receiving anastrozole therapy.

Interpretation

High dietary intake of soy isoflavones was associated with lower risk of recurrence among post-menopausal patients with breast cancer positive for estrogen and progesterone receptor and those who were receiving anastrozole as endocrine therapy.

Footnotes

Funding: This study was funded by grants from the National Natural Science Foundation (30901761) and the Harbin Science and Technology Bureau (2009RFQXS024).

Previously published at www.cmaj.ca

Competing interests: Xinmei Kang and Qingyuan Zhang have received grants from the National Natural Science Foundation (China). None declared for Shuhuai Wang, Xu Huang, and Shi Jin.

Contributors: Xinmei Kang and Qingyuan Zhang were responsible for the conception and design of the study and the collection of data, as well as for writing the manuscript. Shuhuai Wang assisted with study design, recruitment of patients and data collection. Xu Huang was responsible for analyzing the data. Shi Jin assisted with verifying and interpreting the data. All of the authors participated in revising the manuscript for important intellectual content and approved the final version submitted for publication.

This article has been peer reviewed.

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isoflavonen, soja, anastrozole, tamoxifen, hormoongevoelig, borstkanker