The impact of antioxidant supplements on the risk of recurrence, mortality, inflammatory markers, and patient-reported outcomes in women with breast cancer: A systematic review

Abstract

Purpose:

Many
breast cancer (BC) patients take antioxidant supplements during cancer therapy to
improve health outcomes, but little is known about their benefits. This
systematic review aimed to summarise preliminary findings and determine the
impact of antioxidants on clinical and patient-reported outcomes (PROs) among BC
patients receiving cancer treatments.

Methods:

A
search of English-language articles from 2010 onwards was conducted in PubMed,
Web of Science, EMBASE and Cochrane Library. Observational and interventional
studies were considered for inclusion. Antioxidant supplements were defined as oral,
serum and intravenous antioxidants, with dietary antioxidants excluded.

Results:

Eight
eligible studies were identified. Four studies examined disease recurrence and
mortality, one reported inflammation levels, two evaluated PROs (fatigue,
depression, quality of life [QoL], lymphoedema), and one reported both inflammation
levels and cognitive function. Antioxidant use was significantly associated
with a decreased risk of recurrence (HR: 0.78, 95% CI: 0.63-0.95; vitamin C: HR:
0.73, 95% CI: 0.55‐0.97,
vitamin E: HR: 0.71, 95% CI: 0.54‐0.94) and
mortality (HR: 0.82, 95% CI: 0.65-1.02; HR: 0.76, 95% CI: 0.58‐1.00) in two of the four
studies. Findings on reduced inflammation and lymphoedema were significant
(p<0.05), but fatigue, depression and QoL were insignificant. Additionally, antioxidant
supplements may have cognitive benefits.

Conclusions:

Antioxidant
supplements used by these patients may decrease recurrence and mortality,
inflammation and lymphoedema volume, and improve cognitive health. However, inconsistent
results warrant further investigation. Adequately powered studies, with
specific timings and dosages of antioxidants, will be highly beneficial to address
ongoing concerns regarding antioxidant use in managing BC.