[Clinicopathological features and prognosis of synchronous bilateral breast cancers]

Objective: To study the clinicopathologic characteristics and relevant factors affecting prognosis of patients with synchronous bilateral breast cancer. Methods: The clinical data, pathologic characteristics and immunohistochemical expression characteristics of 151 patients with synchronous bilateral breast cancers diagnosed in Peking Union Medical College Hospital from 2008 to 2018 were collected and analyzed. The factors affecting the prognosis were analyzed by Log rank test, Kaplan-Meier survival analysis, Cox regression and other methods. Results: Synchronous bilateral breast cancer cases accounted for 1.2% (151/12 239) of all breast cancer patients in the same period, and 14.6% (22/151) had a family history. The patients' age range was 22-88 years, mainly female, with a mean survival of 42.5 months. There were 106 patients with synchronous bilateral invasive breast cancers, 6 patients with synchronous bilateral breast cancer in situ, and 39 patients with unilateral invasive breast cancer and unilateral breast cancer in situ. In synchronous bilateral invasive breast cancers, the histological type was mainly non-specific type (84.9%, 180/212), the histological grade was mainly Grade 2 (60.8%,129/212), the TNM stage was mainly stage Ⅰ (50.5%, 107/212), the tumor size was mainly T1 (68.9%, 146/212), and the regional lymph node was mainly N0 (61.8%, 131/212). The molecular subtypes were mainly Luminal A-like (38.1%, 75/197) and Luminal B-like (43.7%, 86/197); ER (78.2%, 154/197) and PR (72.1%,142/197)were mainly positive, and HER2 was mainly negative (91.9%, 181/197). There were 85 (80.2%) patients and 75 (70.8%) patients with the same histological type and histological grade on both sides, respectively. The concordance of tumor size T stage and the regional lymph nodes N stage were 58.5% (62/106) and 55.7% (59/106), respectively. The concordance of molecular subtype was 54.9% (50/91), and the concordance of ER, PR, HER2 and Ki-67 were 83.5% (76/91), 76.9% (70/91), 89.0% (81/91) and 59.3% (54/91), respectively. The expression of ER and PR in synchronous bilateral invasive breast cancer was significantly correlated with prognosis (P<0.05). Conclusions: Among patients with synchronous bilateral breast cancers, bilateral invasive breast cancer is the most common, the prognosis is the worst, and the pathologic characteristics of bilateral breast cancer tend to be consistent. The expression of ER and PR in synchronous bilateral invasive breast cancer is significantly correlated with prognosis, that is, best for bilateral ER-positive patients, worst for bilateral ER-negative patients, and intermediate for unilateral ER-positive patients, thus suggesting the importance of ER and PR detection in synchronous bilateral invasive breast cancers.