Plasma isoflavones and the risk of lung cancer in women: a nested case-control study in Japan.
BACKGROUND
Although several epidemiologic studies have found that isoflavone intake assessed by questionnaire is associated with a decreased risk of lung cancer, no prospective study has investigated this association using blood concentrations of isoflavones.


METHODS
We conducted a nested case-control study within a population-based prospective cohort study. A total of 24,127 women aged 40 to 69 years who returned the baseline questionnaire and provided blood samples were observed from 1990 through 2006. During a median follow-up period of 13.5 years, 126 newly diagnosed lung cancer cases were identified. For each case, we selected two controls matched for age, area, smoking status, and condition of blood draw. A conditional logistic regression model was used to estimate the odds ratios (ORs) and 95% CIs of lung cancer in relation to plasma concentrations of genistein, daidzein, glycitein, equol, and total isoflavones.


RESULTS
After exclusion of 20 lung cancer cases diagnosed in the first 3 years after blood collection, an inverse association was found between plasma genistein concentration and lung cancer risk. The multivariate-adjusted OR (95% CI) of lung cancer in the highest quintile of plasma genistein concentration as compared with that in the lowest quintile was 0.31 (0.12, 0.86; P for trend=0.085). Other isoflavones and total isoflavones were not associated with a significant decrease in the risk of lung cancer.


CONCLUSIONS
Plasma genistein concentration was inversely associated with lung cancer risk in Japanese women.


CONCLUSIONS
Our data support the previously observed association between isoflavone intake and lung cancer risk.
Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, 104-0045 Japan. tshimazu@ncc.go.jp
Taichi
T
Shimazu
Manami
M
Inoue
Shizuka
S
Sasazuki
Motoki
M
Iwasaki
Norie
N
Sawada
Taiki
T
Yamaji
Shoichiro
S
Tsugane
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D019833:Genistein / Q000097:blood; D006801:Humans; D007529:Isoflavones / Q000097:blood*; D007564:Japan / Q000453:epidemiology; D008175:Lung Neoplasms / Q000097:blood*; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors
D007529:Isoflavones; D019833:Genistein