Breast cancer survival among young women: a review of the role of modifiable lifestyle factors

Abstract

Almost 7% of breast cancers are diagnosed among women age 40 years and younger in Western populations. Clinical outcomes among young women are worse. Early age-of-onset increases the risk of contralateral breast cancer, local and distant recurrence, and subsequent mortality. Breast cancers in young women (BCYW) are more likely to present with triple-negative (TNBC), TP53-positive, and HER-2 over-expressing tumors than among older women. However, despite these known differences in breast cancer outcomes and tumor subtypes, there is limited understanding of the basic biology, epidemiology, and optimal therapeutic strategies for BCYW. Several modifiable lifestyle factors associated with reduced risk of developing breast cancer have also been implicated in improved prognosis among breast cancer survivors of all ages. Given the treatment-related toxicities and the extended window for late effects, long-term lifestyle modifications potentially offer significant benefits to BCYW. In this review, we propose a model identifying three main areas of lifestyle factors (energy imbalance, inflammation, and dietary nutrient adequacy) that may influence survival in BCYW. In addition, we provide a summary of mechanisms of action and a synthesis of previous research on each of these topics.

Keywords: Breast cancer; Epidemiology; Lifestyle; Modifiable factors; Survival; Young onset.

Fig. 1

Proposed biologic model depicting how multiple lifestyle risk factors may influence breast cancer prognosis through a pro-inflammatory state including important exposures, pathways, and impact on the candidate biologic mediators Green arrows indicate potentially beneficial factors; red arrows indicate potentially detrimental factors. (Color figure online)

Fig. 2

Potential period for lifestyle modification to impact outcomes in breast cancer patients according to age at first diagnosis Compared to women at the median age of diagnosis, young women (<40 years) have approximately twice the duration of post-diagnostic/post-treatment life during which their risk of disease and treatment-related consequences are elevated. The opportunity to mitigate these effects through lifestyle modification is much greater for younger women