Dietary flaxseed alters tumor biological markers in postmenopausal breast cancer.
OBJECTIVE
Flaxseed, the richest source of mammalian lignan precursors, has previously been shown to reduce the growth of tumors in rats. This study examined, in a randomized double-blind placebo-controlled clinical trial, the effects of dietary flaxseed on tumor biological markers and urinary lignan excretion in postmenopausal patients with newly diagnosed breast cancer.


METHODS
Patients were randomized to daily intake of either a 25 g flaxseed-containing muffin (n = 19) or a control (placebo) muffin (n = 13). At the time of diagnosis and again at definitive surgery, tumor tissue was analyzed for the rate of tumor cell proliferation (Ki-67 labeling index, primary end point), apoptosis, c-erbB2 expression, and estrogen and progesterone receptor levels. Twenty-four-hour urine samples were analyzed for lignans, and 3-day diet records were evaluated for macronutrient and caloric intake. Mean treatment times were 39 and 32 days in the placebo and flaxseed groups, respectively.


RESULTS
Reductions in Ki-67 labeling index (34.2%; P = 0.001) and in c-erbB2 expression (71.0%; P = 0.003) and an increase in apoptosis (30.7%; P = 0.007) were observed in the flaxseed, but not in the placebo group. No significant differences in caloric and macronutrient intake were seen between groups and between pre- and posttreatment periods. A significant increase in mean urinary lignan excretion was observed in the flaxseed group (1,300%; P < 0.01) compared with placebo controls. The total intake of flaxseed was correlated with changes in c-erbB2 score (r = -0.373; P = 0.036) and apoptotic index (r = 0.495; P < 0.004).


CONCLUSIONS
Dietary flaxseed has the potential to reduce tumor growth in patients with breast cancer.
Thompson
Lilian U
LU
Department of Nutritional Sciences, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada.
Chen
Jian Min
JM
Li
Tong
T
Strasser-Weippl
Kathrin
K
Goss
Paul E
PE
D000284:Administration, Oral; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D004032:Diet; D004311:Double-Blind Method; D005260:Female; D019597:Flax; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D017705:Lignans / Q000652:urine; D008875:Middle Aged; D008517:Phytotherapy; D010919:Placebos; D017698:Postmenopause; D011446:Prospective Studies; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis*
D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D017705:Lignans; D010919:Placebos; D018719:Erb-b2 Receptor Tyrosine Kinases