High soy intake may cut fracture risk in younger breast cancer survivors

(HealthDay)—Higher soy consumption is linked to fewer osteoporotic fractures in younger breast cancer survivors, according to a study published online May 21 in JNCI Cancer Spectrum.

Neil Zheng, from Yale University in New Haven, Connecticut, and colleagues investigated incidence of osteoporotic bone fracture and its associations with soy food consumption, exercise, and body mass index among 4,139 stage 0 to III breast cancer patients, 1,987 pre-/perimenopausal patients and 2,152 postmenopausal patients participating in the Shanghai Breast Cancer Survival Study.

The researchers found that the 10-year incidence for osteoporotic fractures was 2.9 percent for pre-/perimenopausal and 4.4 percent for postmenopausal patients. There was an association between high soy isoflavone intake and reduced risk among pre-/perimenopausal patients (hazard ratio [HR], 0.22 [95 percent confidence interval [CI], 0.09 to 0.53] for soy isoflavone mg/d ≥56.06 versus < 31.31; P_trend < 0.001), but not among postmenopausal patients (P_interaction < 0.01). Compared to normal weight, overweight was a risk factor for pre-/perimenopausal patients (HR,1.81; 95 percent CI, 1.04 to 3.14), but not for postmenopausal patients (HR, 0.67; 95 percent CI, 0.43 to 1.03; P_interaction = 0.01). There was an inverse association between exercise and osteoporotic fractures in postmenopausal patients (HR, 0.56 [95 percent CI, 0.33 to 0.97] for metabolic equivalents hours ≥12.6 versus <4.5) with a dose-response pattern (P_trend = 0.035).

"Our findings, especially the novel association of soy food intake with osteoporotic fractures in breast cancer survivors, if confirmed, can help guide future strategies for fracture risk reduction in this vulnerable population," the authors write.