Is there different correlation with prognostic factors between "non-mass" and "mass" type invasive ductal breast cancers?

PURPOSE: To investigate the association between non-mass type breast cancer and common clinical-pathological prognostic factors, compared with mass type breast cancer.
MATERIALS AND METHODS: After institutional review board approval, retrospective blind review of contrast-enhanced breast MRI was carried out for 88 histologically proven breast invasive ductal carcinoma (IDC) patients, presenting from January 2008 to December 2011. Two radiologists assessed the images of each lesion for the morphologic enhancement type [mass enhancement or non-mass-like enhancement (NMLE)] and the distribution/internal enhancement of NMLE. Two pathologists evaluated the histological grade of IDC, presence or absence of ductal carcinoma in situ (DCIS), lymph node status, presence or absence of vascular invasion, and expression status of estrogen receptor (ER)/progesterone receptor (PR)/HER-2/p53 tumor suppressor gene (p53)/Ki-67. Inter-observer agreement was assessed with kappa test. Chi-square test and Spearman rank correlation were performed to explore the associations of morphologic enhancement type with the age, lesion size and the above pathological prognostic factors
RESULTS: Inter-observer agreement was excellent, with kappa>0.75. Morphologic enhancement type was significantly correlated with age (P=0.02), with NMLE more commonly seen in women less than 50 y/o. The size of NMLE was larger than that of mass and, with the increase of lesion size, proportion of NMLE among the cases increased (P=0.001). NMLE was also significantly correlated with low histologic grade of IDC (P=0.003) and presence of DCIS (P<0.001). There was no significant correlation between morphologic enhancement type and lymph node status, vascular invasion, ER/PR/HER-2/p53/Ki-67 status. The histological grade was higher in clumped enhancement than non-clumped (P=0.011). There was no correlation between enhancement distribution and prognostic factors
CONCLUSIONS: Non-mass type breast cancer may not necessarily have worse prognosis than the mass type, due to lower histological grade and closely related to DCIS component, although it may has larger tumor size. Clumped enhancement may have worse prognosis than non-clumped enhancement.