Breast cancer (BC) is one of the common malignant tumors in women and affects 1.6 million new cases globally each year. Investigators have recently found that negative emotions (NEs) and their impacts have greatly influenced the incidence and risk of BC. The present study aims to provide an association between NEs and the incidence of BC with possible risk factors. A total of 9343 studies were screened; nine studies met all inclusion criteria that were considered for the meta-analysis. The qualitative studies were measured by the Newcastle-Ottawa Scale; the observational studies were included with relative risks (RR) and corresponding 95% confidence intervals (CI). Besides the NEs and BC, the possible risk factors were evaluated. We analyzed data from 129,621 women diagnosed with NEs of which 2080 women were diagnosed with BC and their follow-up year ranges were from 4-24 years. NEs were significantly (p < 0.0001) associated with a higher incidence of BC with RR = 1.59, 95% CI:1.15-2.19, with other high-risk factors including, geographical distribution, emotion types, standard diagnosis of NEs, and follow-up duration. This study suggests that NEs significantly increase the risk for the incidence of BC, which can be supportive of the prognosis of the disease.
Keywords: breast cancer; emotion types; follow-up; negative emotions; prognosis.