fa Supportive and Palliative Care Original/Research Article <div style="text-align: justify;"><strong>Introduction:</strong> Invasive ductal carcinoma (IDC) is the most common form of breast cancer, including 80 percent of all breast cancer diagnoses. The objective of our retrospective cohort study was to investigate patterns of subtype-specific metastatic spread in these patients.</div> <div style="text-align: justify;"><strong>Materials and Methods:</strong> Patients with IDC referred to Breast Diseases Research Center affiliated with Shiraz University of Medical Sciences, and diagnosed between the years 1993 and 2017 were included. Statistical analysis was performed via SPSS Statistics for Windows, Version 21.</div> <div style="text-align: justify;"><strong>Results:</strong> Mean follow-up time among 4674 eligible patients was 46 months (range 0-277 months). The longest Distant Metastasis Free Survival (DMFS) time was observed in the Luminal B subtype (mean 194 months) whereas the shortest was observed in the Triple Negative Breast Cancer (TNBC) subtype (mean 129 months, P=0.006).The lowest DMFS rate pertained to TNBC tumors (73.8%). Luminal A-associated metastases were found to be solitary in 83.1% of cases, whereas HER2+ tumors showed multi-organ relapses in 30.5% of cases. Luminal A and B tumors expressed a preference for bone metastasis (55.3% vs. 36.5) while HER2+ and TNBC cases showed liver (40.7%) and lung (36.4%) metastasis, respectively, as the most common site of metastasis.</div> <div style="text-align: justify;"><strong>Conclusions:</strong> These findings further represent that breast tumor subtypes differ not only</div> in tumor characteristics but also in their metastatic behavior. TNBC tumors featured the most aggressive clinical course. Further identification of subtype-specific factors influencing prognosis might have an impact on appropriate strategy for follow-up of newly diagnosed IDC breast cancer patients. Invasive Ductal Carcinoma, Breast Cancer Subtypes, Metastatic Behavior 0 0 http://mcijournal.com/browse.php?a_code=A-10-33-98&slc_lang=fa&sid=1 Majid Akrami 1003194753284600931 1003194753284600931 Yes S Tahmasebi 1003194753284600932 1003194753284600932 No V Zangouri 1003194753284600933 1003194753284600933 No S Hosseini 1003194753284600934 1003194753284600934 No Ar Talei 1003194753284600935 1003194753284600935 No