| BackgroundBreast cancer is the most common malignant tumor in the female population.As a paired organ in the human body,bilateral breasts are affected by the same external environment,gene regulation and other factors.When one suffers from breast cancer,the contralateral breast will also take the corresponding risk of disease.Synchronous bilateral breast cancer is defined in most studies when the bilateral primary breast cancer occurs less than 6 months apart.Metachronous bilateral breast cancer is defined as bilateral breast cancer diagnosed more than 6 months later.The analysis of clinicopathological features of bilateral breast cancer is more common in foreign literature,but less in China.Therefore,it is of great clinical significance to explore the clinicopathological characteristics of domestic bilateral breast cancer patients and analyze the potential related factors of bilateral breast cancer.ObjectiveThe aim of this study is to investigate the differences in clinicopathological characteristics between synchronous and metachronous bilateral breast cancer,and between bilateral and unilateral breast cancer,and to explore the relationship between related factors and the incidence of bilateral breast cancer.MethodIn this study,case data of patients with breast cancer admitted to Qilu Hospital of Shandong University from January 2011 to September 2022 were collected.According to the inclusion and exclusion criteria,patients with bilateral breast cancer were selected as the research objects,and patients with unilateral breast cancer from 2011 to 2012 without contralateral breast cancer for 10 years were selected as the control group.The study collected the clinical and pathological data of relevant patients.Two-tailed t test,rank sum test and chi-square test were used for univariate analysis and the relevant factors with differences were included in the logistic regression equation for multivariate analysis.P value of less than 0.05 was considered to indicate statistical significance.ResultsA total of 7730 breast cancer patients were treated in our hospital during the study period,including 283 cases of bilateral breast cancer,accounting for 3.66%of the total breast cancer patients during the same period.There were 154 cases of synchronous bilateral breast cancer and 129 cases of metachronous bilateral breast cancer.Most patients with synchronous breast cancer were diagnosed at the same time on bilateral breast.In patients with metachronous bilateral breast cancer,the longest interval between bilateral breast cancer diagnosis was 36 years,with a median time of 95 months.Patients with bilateral interval of 5-10 years were the most,accounting for about 30.23%.The mean age at diagnosis was 50.2±11.52 years in patients with bilateral breast cancer and 49.34±10.58 years in patients with unilateral breast cancer.The mean age of patients with synchronous breast cancer was 53.90±11.48 years,while the mean age of patients with metachronous breast cancer was 45.84±9.96 years.The proportion of patients with a family history of breast cancer was 12.7%in the bilateral breast cancer group and 5.0%in the unilateral breast cancer group,which was statistically significant.The concordance of bilateral invasive ductal carcinoma,ER positive and PR positive expression in synchronous bilateral breast cancer was significantly higher than that in metachronous bilateral breast cancer.There was no significant difference in the overall composition of pathological features between the bilateral tumors in bilateral breast cancer.Compared with unilateral breast cancer,synchronous bilateral breast cancer had more lobular histology,lower infiltrating histological grade,more carcinoma in situ,smaller mass and earlier stage.Immunohistochemical staining showed more ER positive,more PR positive,more HER-2 positive,and lower Ki-67 expression rate,which was statistically significant.Multivariate analysis showed that older age,family history of breast cancer and HER-2 positivity were associated with an increased risk of synchronous bilateral breast cancer.Compared with patients with unilateral breast cancer,patients with metachronous bilateral breast cancer had fewer births,more ER negative expression,more PR negative expression,and more HER-2 positive expression.Multivariate analysis showed that younger age at onset,no endocrine therapy and no radiotherapy were associated with an increased risk of metachronous bilateral breast cancer.Conclusion1.Bilateral breast cancer is not rare in clinical practice,accounting for about 3.66%of breast cancer patients in the same period.2.Patients with unilateral breast cancer have a long-term risk of contralateral breast cancer(40%of patients have an interval of more than 10 years),especially those with a family history of breast cancer.3.The pathological features of synchronous bilateral breast cancer tend to be more concordant than the metachronous bilateral breast cancer.4.Synchronous bilateral breast cancer has the characteristics of older age,more lobular histology,lower grade and stage,more hormone receptor positive and lower Ki-67.5.Patients with metachronous bilateral breast cancer were younger and hormone receptor negative was more common than synchronous and unilateral breast cancer. |
