Clinical Characteristics and Prognosis of Pregnancy-Associated Breast Cancer: Poor Survival of Luminal B Subtype

Abstract

Background: Pregnancy-associated breast cancer (PABC) is rare and is generally defined as breast cancer diagnosed during pregnancy or within 1 year of delivery. The average ages of marriage and childbearing are increasing, and PABC is expected to also increase. This study is intended to increase understanding of the characteristics of PABC. Methods: A database of 2,810 patients with breast cancer diagnosed when they were less than 40 years of age was reviewed. The clinicopathological factors and survival of PABC (40 patients) were compared to those of patients with young breast cancer (YBC, non-pregnant or over 12 months after delivery; 2,770 patients). Results: PABC had significantly lower estrogen receptor (ER) and progesterone receptor (PR) expression (ER-positive 50.0%, PR-positive 45.0%) and higher HER2 overexpression (38.5%) than YBC. The most common subtype of PABC was triple-negative breast cancer (TNBC; 35.9%), and luminal A subtype represented only 7.7% of cases. In univariate analysis, PABC had significantly worse disease-free survival (DFS) and breast cancer-specific survival (BCSS) compared to YBC. In multivariate analysis, PABC was associated with worse BCSS (HR 4.0, 95% CI 1.2–12.9, p = 0.019) and survival, but there was no difference in DFS between PABC and YBC. In subgroup analysis by subtype, luminal B subtype of PABC showed worse DFS (HR 3.5; 95% CI 1.1–11.2, p = 0.039) and BCSS (HR 10.2, 95% CI 1.2–87.1, p = 0.035), especially with high Ki67. However, no differences were demonstrated in other subtypes. Conclusion: In this study, PABC showed lower expression of ER/PR, higher overexpression of HER2, fewer luminal A subtype, and more TNBC subtype compared to YBC. PABC had worse BCSS, especially luminal B subtype, compared to YBC.

Clinicopathological characteristics, diagnosis, and prognosis of pregnancy‐associated breast cancer

“…According to the literature available, the average age of PABC patients varies from 32 to 38 years . In our population, the median and mean onset age was 30 years, slightly younger than the previous reported age, which might be associated with the younger age of onset of breast cancer and obstetrical history in China.…”

“…In addition, 41.5% of cases were grade II and 17.0% of cases grade III, which was consistent with the results of previous studies showing that PABC tends to be associated with high histological grades . PABC is thought to exhibit other adverse biologic features, such as more frequent ER and PR negative status, and a high rate of HER2/neu overexpression or amplification . In this study, 45.7% of PABC patients were ER and PR negative and 30% showed HER2 overexpression.…”

“…Although several previous studies have reported that PABC prognosis is similar to that of non‐PABC when matching for stage, age, and histology, most studies have reported that PABC is associated with a poorer prognosis . In our study, the tumor was aggressive with more patients at advanced T/N stage, and the five‐year OS and DFS rates were 72.3% and 56.1%, respectively, which indicated a poorer prognosis compared to non‐PABC patients.…”

“…Previous studies have yielded controversial results regarding PABC prognosis. Most studies describe it has having adverse biological characteristics with a relatively poor outcome, while other studies have suggested that the poor survival rates are the result of adverse pathologic features rather than pregnancy …”

“…Previous studies have yielded controversial results regarding PABC prognosis. Most studies describe it has having adverse biological characteristics with a relatively poor outcome, [5][6][7][8] while other studies have suggested that the poor survival rates are the result of adverse pathologic features rather than pregnancy. 9,10 In this retrospective study we reviewed the clinical characteristics, imaging, and pathologic features of 142 PABC patients who had been diagnosed and treated in our hospital to evaluate the therapeutic strategies and analyze prognostic factors.…”