Background and purpose: The time from first onset of symptoms or signs to a definitive diagnosis is defined as diagnostic interval (DI). The relation of DI to other clinicopathological parameters and the impact of DI on prognosis of patients with triple-negative breast cancer (TNBC) remain unclear. This article plans to make an intensive study of these questions. Methods: The clinical records of a series of 83 consecutively presenting unselected patients referred to the Shanghai Sixth People’s Hospital with diagnosed TNBC between September 2009 and September 2015

were retrospectively reviewed. Clinical and pathological factors included were investigated by univariate analysis using the Kaplan-Meier method

the factors associated with prognosis were further evaluated by multivariable analysis with Cox progression model. t-test and Kruskal-Wallis test were used to study the correlation between DI and other characters. Results: DI: stage T

3

T

1

(P=0.01)

stage ⅢⅡ (P=0.03) and Ⅰ (P=0.01). Compared with patients of DI≥3 months

the 3 months group had earlier age (P=0.028) and TNM stage (P=0.035). T stage

N stage

neoadjuvant chemotherapy

TNM stage and DI are influencing factors of overall survival (OS). Age

T stage

N stage

TNM stage

menstrual status and neoadjuvant chemotherapy are influencing factors of progression-free survival (PFS). TNM staging is an independent influencing factor for OS and PFS. Conclusion: Patients with later disease stage were more likely to have a longer DI; The shorter DI

the earlier age and stage of disease; DI is the influence factor of OS; TNM stage is an independent influencing factor for OS and PFS.