Abstract 3719: Fruit and vegetable intake and risk of breast cancer characterized by estrogen receptor (ER) and progesterone receptor (PR) status

Abstract

Abstract Background: Breast cancer is suggested to be a heterogeneous disease due to risk factors and prognosis differing by hormone receptor status. However, few studies have investigated intakes of fruits and vegetables, important sources of phytochemicals, in relation to the risk of breast cancer subtypes defined by hormone receptor status. Methods: We conducted a pooled analysis using the primary data from 21 prospective cohort studies in North America, Europe, Asia, and Australia. Among 1,105,283 women followed up for up to 11 to 20 years, 22,329 ER-positive (ER+), 5,403 ER-negative (ER-), 17,969 PR-positive (PR+), and 8,354 PR-negative (PR-) incident breast cancer cases were diagnosed. Fruit and vegetable intake was measured at baseline in each study using validated diet assessment instruments. We calculated study-specific multivariate relative risks (RRs) using Cox proportional hazards models and combined these estimates using a random-effects model. We examined the presence of heterogeneity across studies using the Q-statistic. We tested the significance of the associations across breast cancer subtypes using a contrast test. Results: We found a significant inverse association for total vegetable intake with the risk of ER- breast cancer, but not with risk of ER+ breast cancer. The pooled multivariate RRs and 95% confidence intervals (95% CI) comparing the highest to lowest quintile were 0.85 (0.76-0.94) for ER- breast cancer and 1.03 (0.96-1.09) for ER+ breast cancer (P-value, test for heterogeneity by receptor status for quintile 5 <0.01). Total fruit and vegetable intake and total fruit intake were not associated with risk of either ER- or ER+ breast cancer. Similar associations were observed when we categorized intake using absolute intake cut-points. For example, inverse association was observed only between total vegetable intake and ER- breast cancer. The multivariate RRs (95% CI) comparing ≥400 g/day vs. 100 to <200 g/day of total vegetable intake were 0.86 (0.76-0.97) for ER- and 1.03 (0.97-1.08) for ER+ breast cancer. Among the specific foods examined, only lettuce/salad, strawberries, and peaches had significant inverse associations with risk of ER- breast cancer. For an increment of 3 servings/week, the pooled multivariate RRs (95% CI) for ER- breast cancer were 0.96 (0.93-1.00) for lettuce/salad, 0.78 (0.69-0.89) for strawberries, and 0.92 (0.87-0.98) for peaches. None of the specific foods examined was associated with the risk of ER+ breast cancer. No associations with risk of PR- and PR+ breast cancer were observed for intakes of total fruits and vegetables, total fruits, total vegetables, or any of the specific foods. Conclusions: These results support an inverse association between vegetable consumption and risk of ER- breast cancer. Further studies should elucidate the potential role of diet in preventing this more aggressive breast cancer subtype. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3719. doi:10.1158/1538-7445.AM2011-3719