Diet Quality Indices and Postmenopausal Breast Cancer Survival

Abstract

Research on diet in breast cancer survival has been focused on single nutrients or foods, particularly dietary fat, fruits, vegetables, fiber, and alcohol. We hypothesized that diet quality indices decrease the risk of total and non-breast-cancer-related deaths in women diagnosed with breast cancer. We evaluated 4 dietary quality scores: Alternate Healthy Eating Index (AHEI), Diet Quality Index—Revised (DQIR), Recommended Food Score (RFS), and the alternate Mediterranean Diet Score (aMED), among 2,729 women from the Nurses’ Health Study with invasive Stage 1–3 breast cancer diagnosed between 1978 and 1998 with follow-up through 2004. In multivariate adjusted analyses, no association was found between diet quality indices and either total or non-breast-cancer-related deaths. However, a higher aMED score was associated with a lower risk of non-breast-cancer death in women with low physical activity; the RR comparing the highest to lowest tertile was 0.39 (95% CI, 0.20–0.75, P trend = 0.0004). Our results suggest that a higher-quality diet after breast cancer diagnosis does not considerably change the risk of death from breast cancer. However, healthy dietary choices may be important because women are at risk of death from non-breast-cancer-related causes affected by diet.

ACKNOWLEDGMENT

We wish to acknowledge the invaluable assistance of Dr. Diane Feskanich. This study was supported by the National Institutes of Health (CA 87969).

Notes

*Time since diagnosis and age adjusted.

**Multivariate models adjusted for: time since diagnosis, age (continuous), alcohol intake in g/day (0, 0.1–1.0, 1.1–6.3, >6.3, missing), only for RFS because alcohol is a component in the other 3 diet quality indices), energy (quintiles), multivitamin use (yes, no, missing, except for AHEI because it is a component), body mass index in kg/m² (<22, 22–24.9, 25–29.9, 30–34.9, ≥35, missing), body mass index (BMI), weight change (BMI at time of diet minus BMI just prior to diagnosis), oral contraceptive use (yes/no), age, smoking status (never, past, current), physical activity in METs (0, 0.1–3.1, 3.2–9.5, 9.6–21, >21), stage (1, 2, 3), categories of treatment (chemotherapy = no/radiation = no/tamoxifen = no, chemotherapy = no/radiation = yes or no/tamoxifen = yes, chemotherapy = yes/radiation = no/tamoxifen = yes, chemotherapy = no/radiation = yes/tamoxifen = no, chemotherapy = yes/radiation = yes/tamoxifen = no, chemotherapy = yes/radiation = no/tamoxifen = no, chemotherapy = yes/radiation = yes/tamoxifen = yes, treatment = missing), age at first birth and parity (nulliparous, age <25 and 1 birth, age <25 and 2 births, age <25 and ≥3 births, age ≥30 and 1 birth, age ≥30 and 2 births, age ≥30 and ≥3 births, missing), menopausal status and postmenopausal hormone use (premenopausal, postmenopausal and never use, postmenopausal and past use, postmenopausal and current use, missing).

*Time since diagnosis and age adjusted.

**Adjusted for the same factors in Table 2.

*Time since diagnosis and age adjusted.

**Adjusted for the same factors in Table 2.

*Adjusted for the same factors in Table 2 except physical activity was excluded.