[Colorectal cancer prevention by flavonoids].
BACKGROUND
Valid, sustained and safe clinical means of colorectal cancer prevention are still lacking, but they are urgently needed to lower the incidence of colorectal cancer. Dietary factors and phytochemicals such as flavonoids play an important role for prevention.


METHODS
A selective search of the literature using PubMed was performed with the following key words: flavonoids, cancer, therapy, colorectal cancer focused on clinical queries. Results of clinical studies including the authors' own were compared.


RESULTS
In vivo and in vitro studies with animals, cell cultures and subcellular components provide ample evidence for antimutagenic and anticarcinogenic effects of flavonoids as shown for multiple biological and molecular endpoints. Isoflavonoids in vitro have been shown to induce proliferation of breast cancer cells. Epidemiologic trials (cohort, case-control and cross-sectional studies) yielded inconsistent results for flavonoid protection. Systematic reviews and meta-analyses support the protective role of tea flavonoids on adenoma incidence. An interventional pilot study with sustained flavonoid supplementation was shown to reduce the rate of neoplasia in patients with resected colorectal cancer.


CONCLUSIONS
Selected flavonoids possess antimutagenic and anticarcinogenic properties and could reduce the incidence of colorectal neoplasias as shown in epidemiologic trials. Randomized controlled clinical studies with flavonoid intervention are necessary to provide evidence for their role in colorectal cancer prevention.
Hoensch
Harald
H
Privat-Praxis Innere Medizin und Gastroenterologie, Marienhospital Darmstadt, Darmstadt, Germany. h.p.hoensch@t-online.de
Richling
Elke
E
Kruis
Wolfgang
W
Kirch
Wilhelm
W
D000236:Adenoma / Q000517:prevention & control* / Q000601:surgery; D000818:Animals; D016588:Anticarcinogenic Agents / Q000008:administration & dosage*; D016587:Antimutagenic Agents / Q000008:administration & dosage*; D015179:Colorectal Neoplasms / Q000517:prevention & control* / Q000601:surgery; D005419:Flavonoids / Q000008:administration & dosage*; D006801:Humans; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control; D014407:Tumor Cells, Cultured / Q000187:drug effects
D016588:Anticarcinogenic Agents; D016587:Antimutagenic Agents; D005419:Flavonoids
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