Clinicopathologic Features Of Neuroendocrine Carcinoma Of The Breast And Its Relationship With Prognosis

Background:Neuroendocrine carcinoma of the breast (NEC of the breast) is a rare mammary carcinoma that has been reported since the past four decades. In2003the World Health Organization named it as NEC of the breast with an incidence rate of2-5%among all mammary malignancies. NEC of the breast is a distinct disease, with similar clinical features to Invasive ductal carcimoma, not otherwise specialized(IDC, NOS) but different biological features and outcome. It is clinically beneficial to compare the clinicopathologic features of NEC and IDC,NOS and to figure out those diffenences. Prognostic factors of IDC,NOS include age, tumor size, LN metastasis, TNM stage, histological type and hormone receptor expression, which are significant in predicting recurrence risk. Whether these factors still work in NEC of the breast is in debate. NEC of the breast is highly heterogeneous with morphological features characteristic of non-neuroendocrine carcinoma, and different subtypes of NEC can have various histological features. The2003WHO Tumour Series divided NEC of the breast as having three subtypes:solid/carcinoid-like, small cell/oat cell and large cell. With different morphological subtypes having quite different prognosis, it is important to distinguish between them.Methods:We conducted a comparative study on107NEC patients and475invasive ductal carcinoma, not otherwise specified(IDC, NOS) patients from the department of pathology Huashan Hospital, Fudan University, to determine the demographic, pathologic, and clinical features at presentation, along with patient outcomes and prognostic factors.Results:All475patients with IDC,NOS have complete clinical and prognostic data, with follow-up time from2to149months(median,100m). All107patients with NEC have complete clinical and prognostic data, with follow-up time from1to137months (median,36m). There are significant differences in age(P<.0001), menopausal status(P<.0001), tumor size(P=.014), LN metastasis(P=.026), mitotic figure(P=.036), ER(P<.0001), PR(P<.0001), HER2(P<.0001). Also, NEC patients have a significantly better prognosis than IDC,NOS patients with higher OS (P=.03, Log-rank=4.696) and LRFS (P=.043, Log-rank=4.098). Statistical analysis revealed that tumor size(P=.003), distant metastasis(P<.0001), TNM stage(P<.0001), Ki67(p=.009) are related to worse prognosis, while PR(P=.001) is a good prognostic factor. Multivariate analysis showed that distant metastasis is a dependant prognostic factor. Finally, we divided NEC of the breast to six morphological subtypes(solid cohesive, solid papillary, cellular mucinous, alveolar, small cell/oat cell, large cell). Kaplan-Meier survival analysis revealed no significant differences between them.Conclusions:NEC of the breast is a distinct and rare malignancy. Several clinicopathologic features including age, menopausal status, tumor size, LN metastasis, mitotic figure, ER, PR, HER2and OS, LRFS are significantly different with IDC,NOS. Prognostic factors of NEC are tumor size, distant metastasis, TNM stage, Ki67and PR. OS between six morphological subtypes are of no statistical significance.