Ipsilateral breast tumor recurrence (IBTR) after surgical resection in early breast cancer (EBC) patients is categorized into local recurrence following breast-conserving surgery and recurrence on the chest wall after mastectomy. IBTR may represent a true local recurrence (TLR), from growth of residual malignancy (in situ or invasive) or a new primary (NP) tumor, arising in the residual breast tissue. The underlying pathology of IBTR may involve the presence of subclinical residual lesions and tumor cell dormancy induced by resistance to previous adjuvant therapies. Currently, there is a lack of standardized criteria to distinguish between TLR and NP tumors, which poses significant challenges in clinical management. We reviewed the current clinical pathological understanding and discriminant criteria for IBTR, explored the treatment principles for isolated IBTR after EBC, and make the following conclusions. (1) Recurrent and metastatic breast cancer should be regarded as advanced disease states. (2) The likelihood of subclinical lesions and circulating tumor cells being present in the recurrent disease state is much higher than during the adjuvant therapy stage at initial diagnosis. (3) Systemic therapy options after IBTR are often more limited, with reduced efficacy and increased unpredictability. Thus, drug sensitivity testing becomes particularly important. For IBTR, systemic therapy should be considered first. Based on evidence-based medicine, a multidisciplinary team (MDT) should distinguish between TLR from a NP tumor, and formulate an individualized treatment plan.