Impact of Lifestyle Factors on Prognosis Among Breast Cancer Survivors in the USA

Rachel E Ellsworth; Allyson L Valente; Craig D Shriver; Barry Bittman; Darrell L Ellsworth

Expert Rev Pharmacoeconomics Outcomes Res. 2012;12(4):451-464.

Conclusions

A multitude of studies investigating the impact of lifestyle modification on breast cancer survivors have produced highly variable and contradictory results. Large-scale dietary studies indicate that specific dietary components may not affect breast cancer mortality, but achieving and/or maintaining a healthy bodyweight through diet provides health benefits to breast cancer survivors. A body of research has definitively linked physical activity to improved prognosis and survival in breast cancer patients. Chronic stress appears to have an adverse effect on breast cancer incidence and survival, particularly in women with the highest levels of anxiety and depression. Although the actual benefits of psychosocial interventions remain controversial, yoga has shown promising effects on psychological health. Lifestyle factors considered in this review are unlikely to exert a uniform influence on outcomes in breast cancer survivors, thus modalities such as physical activity are likely to have a more significant influence than specific dietary components such as green tea or soy. These findings illustrate the need for continued, high-quality research into the effects of lifestyle interventions in breast cancer patients in order to provide survivors with state-of-the-art knowledge and optimum methods for improving long-term prognosis and QoL.

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Table 1. Large-scale studies evaluating the effects of diet on breast cancer mortality and recurrence.
Study	Type	Participants	Dietary factor(s)	Results	Ref.
NHS	PC	1982	Fat intake	No association	[19]
		2619	Prudent versus Western diet	No association	[21]
		2729	Four dietary quality indices	No association	[22]
LACE	PC	2321	>100 foods, beverages, nutritional supplements and medicinal herbs	No association	[23]
		1901	Prudent versus Western diet	No association	[24]
HEAL	PC	670	Quality versus poor diet	Reduced risk of breast cancer mortality with quality diet	[25]
		746	Quality versus poor diet	Lower CRP levels with quality diet	[26]
		688	Fiber, carbohydrates, glycemic index and glycemic load	Nonsignificant relationship between dietary fiber and breast cancer recurrence and mortality	[27]
WINS	RCT	975 cases; 1462 controls	Low-fat diet versus minimal nutritional counseling	Cases had higher relapse-free survival	[28]
WHEL	RCT	1537 cases; 1551 controls	High-fruit/vegetable versus 5-A-Day for Better Health Program diet	No association	[29]

CRP: C-reactive protein; NHS: Nurses' Health Study; PC: Prospective cohort; RCT: Randomized controlled trial.

Table 2. Large-scale studies evaluating the effects of physical activity on breast cancer mortality and recurrence.
Study	Type	Participants	Physical activity^†	Results	Ref.
NHS	PC	2987	MET hours per week	Lower breast cancer mortality with ≥9 MET hours/week	[62]
LACE	PC	1970	General activity during 6 months prior to enrolment	Lower total mortality associated with higher activity	[63]
CWLS	PC	4482	Postdiagnosis recreational activity	Lower breast cancer mortality with greater levels of activity	[64]
HEAL	PC	933	Physical activity in year prediagnosis and 2 years postdiagnosis	45% lower total mortality with increased activity postdiagnosis; fourfold increase in total mortality with decreased activity	[65]
WHI	PC	4643	Physical activity prediagnosis and 3–6 years postdiagnosis	Lower total mortality with ≥9 MET hours/week prediagnosis; lower breast cancer and total mortality with ≥9 MET hours/week postdiagnosis	[66]
WHEL	PC	2361	Physical activity at baseline and 1 year later	35% lower total mortality with ≥10 MET hours of moderate activity/week	[67]

†All physical activities were self-reported.
MET: Metabolic equivalent task; NHS: Nurses' Health Study; PC: Prospective cohort; WHI: Women's Health Inititative.