by Jenna Koroly, MS, RD, CSOWM, CDN
Although breast cancer has an overall high survival rate, 20-40% of breast cancer patients may develop recurrence [Takeshita et al., 2019 as cited in reference i]. Lifestyle factors such as eating pattern have been associated with decreased risk of breast cancer. For example, the Dietary Approaches to Stop Hypertension (DASH) and the Chinese Food Pagoda (CHFP) have been found to be inversely associated with all-cause mortality in breast cancer survivors [Wang et al., 2020 & Kwan et al., 2009 as cited in reference i]. One component of an overall nutritious eating pattern is nuts, which have been shown to decrease cardiovascular disease related mortality [van den Brandt et al., 2015 as cited in reference i]. In the below study, the authors explore nut intake, overall survival (OS), and disease-free survival (DFS) in breast cancer survivors.
Study
Nut consumption in association with overall mortality and recurrence/disease-specific mortality among long-term breast cancer survivors
Cancer Epidemiology
This longitudinal, population-based study included 3449 breast cancer survivors from the Shanghai Breast Cancer Survival Study (SBCSS) who were diagnosed with primary breast cancer from March 2002 to April 2006. Participants were enrolled 6.5 months after diagnosis, and completed in-person interviews including a questionnaire on demographics, lifestyle factors, and quality of life. Clinical information regarding type of cancer and treatment was also collected. In-person follow-up surveys were conducted 18 months, 3 years, 5 years, and 10 years after diagnosis, and collected information about recurrence, metastasis, and comorbidities. At the 5 year follow-up, a food frequency questionnaire (FFQ) was administered. The FFQ contained questions about nut consumption, including peanuts, walnuts, and other nuts. Those that had >0 grams per week of nuts were considered nut consumers, and those with no consumption were considered non-consumers [i].
Findings
The authors found:
1. Nut consumers had higher OS and DFS rates compared to non-consumers at 10-years post-diagnosis. Similar survival differences were found for peanut, walnut, and other nut consumption.
2. Nut consumers of greater than the median (17.32 grams of nuts per week) had a 52% decreased risk of cancer recurrence, metastasis, or breast cancer-specific death compared to non-consumers. Nut consumers of equal to or less than the median had a 45% decreased risk of cancer recurrence, metastasis, or breast cancer-specific death compared to non-consumers.
3. Higher nut consumption was associated with significantly better OS in those with higher total energy intake.
4. Higher nut consumption was associated with significantly better DFS in those with Stage I and II breast cancers [i].
For the Patient and Caregiver
The median nut consumption in this study was 17.32 grams of nuts per week, compared to the 42.5 grams per week recommended by the American Heart Association [Go nuts (but just a little!) from the AHA as cited in reference i]. To put that into perspective, 28 grams is 1 oz, which is about ¼ cup of nuts. To increase your nut intake, consider mixed nuts as a nutritious snack, sprinkle them over Greek yogurt, oatmeal, or salads, and add chopped nuts when baking your favorite desserts. All peanuts and tree nuts have varying nutritional profiles. Peanuts, almonds, and pistachios are rich in protein, walnuts are rich in polyunsaturated fats, and pecans are rich in monounsaturated fats. Nuts also provide vitamins and minerals including certain B vitamins, vitamin E, vitamin A, calcium, magnesium, and potassium, depending on the nut.
For the Healthcare Team
In vitro studies have found that certain components of nuts such as ellagic acid, alpha-linolenic acid, and beta-sitosterol may inhibit growth of breast cancer MCF-7 cells, which may help prevent recurrence [Chen et al., 2015, Heuvel et al., 2012, & Awad et al., 2000 as cited in reference i]. Consumption of nuts may lower cholesterol levels, inhibit oxidation, and regulate endothelial dysfunction, which may also improve DFS and OS in breast cancer survivors [Del Gobbo et al., 2015, Jenkins et al., 2006, Torabian et al., 2009, Stockler-Pinto et al., 2014, & Ma et al., 2010 as cited in reference i]. The authors found an association between nut intake and total energy intake on OS and nut intake and breast cancer stages I and II on DFS. They explain that this may partially be related to those with higher energy intake and early stage breast cancer being overall healthier than those with lower energy intake and later stage breast cancer. For example, the authors found that those with higher energy intake were younger, had a higher BMI, higher physical activity, higher CHFP-2007 score, and lower comorbidity [i]. It may be beneficial to recommend nut intake to patients as part of a nutritious eating pattern, particularly if they are breast cancer survivors or at risk of cardiovascular disease.
Reference:
[i] Wang C, Gu K, Wang F, Cai H, Zheng W, Bao P, Shu X (2021). Nut consumption in association with overall mortality and recurrence/disease-specific mortality among long-term breast cancer survivors. Cancer Epidemiology. https://doi.org/10.1002/ijc.33824