Prognosis of pregnancy-associated breast cancer: inferior outcome in patients diagnosed during second and third gestational trimesters and lactation

Biology, care, and outcomes of gestational breast cancers: a review

PURPOSE

The incidence of gestational breast cancers, breast cancers diagnosed during pregnancy, is increasing. There is a critical need to understand the pathophysiology, treatment recommendations, and remaining questions regarding care and therapeutics for this complex condition.

METHODS

Here, we review existing data regarding evaluation and management of gestational breast cancer, including safe imaging modalities, timing and choice of chemotherapy, evidence regarding targeted therapies during pregnancy. We highlight the importance of multidisciplinary care including oncologic, obstetric, and psychosocial care.

RESULTS

Gestational breast cancers are associated with unique biologic and clinicopathologic features that are impacted by physiologic changes of pregnancy such as upregulation of target genes associated with cell proliferation and immune regulation. Patients with gestational breast cancers more often present at advanced stages, are more likely to have aggressive tumor subtypes (i.e., triple negative or HER2 positive), and overall have worse prognoses than patients with non-gestational breast cancers. In this review, we synthesize recommendations for treatment strategies based on pregnancy trimester, optimal timing and choice of surgery, chemotherapy, targeted therapies, and psychosocial support.

CONCLUSION

Developing a framework for clinical care and treatment of patients with gestational breast cancers is integral to improving outcomes for patients with gestational breast cancers. Optimal treatment includes collaborative management with a multidisciplinary team dedicated to both maternal and fetal care.

Impact of Pregnancy on Breast Cancer Features and Prognosis

BACKGROUND

pregnancy-associated breast cancer (PABC) affects one in 3000 pregnancies, often presenting with aggressive features.

METHODS

We retrospectively evaluated a cohort of 282 young BC patients (≤45 years old) treated between 1995 and 2019, dividing them into three groups: nulliparous women, women with PABC (diagnosed within 2 years since last pregnancy) and women with BC diagnosed > 2 years since last pregnancy. This last group was further stratified according to the time between pregnancy and BC. The analysis encompassed histological factors (tumor size, histotype, grading, nodal involvement, multifocality, lympho-vascular invasion, hormone receptor expression, Ki-67 index, and HER2 expression), type of surgery and recurrence.

RESULTS

Age at diagnosis was younger in nulliparous than in parous women (p < 0.001). No significant differences were noticed regarding histological characteristics and recurrences. At univariate analysis, nodal involvement (OR = 2.4; p < 0.0001), high tumor grade (OR = 2.6; p = 0.01), and lympho-vascular invasion (OR = 2.3; p < 0.05), but not pregnancy (OR = 0.8; p = 0.30), influenced DFS negatively. Multivariate analysis confirmed nodal involvement as the only negative independent prognostic factor for a worse DFS (OR = 2.4; p = 0.0001).

CONCLUSIONS

in our experience, pregnancy is not an independent adverse prognostic factor for BC DFS.

Worse histopathology and prognosis in women with breast cancer diagnosed during the second trimester of pregnancy

BACKGROUND

Evidence suggests that women with breast cancer diagnosed during pregnancy (PrBC) and within 2 years of delivery (PPBC) have similar survival compared to women diagnosed not near pregnancy if adjusted for stage and subtype. To investigate whether this is true for all subtypes and for both pregnancy and post-delivery periods, we examined clinicopathologic features and survival in women with breast cancer by trimesters and 6-month post-delivery intervals.

MATERIALS AND METHODS

Women diagnosed with invasive breast cancer during 1992-2018 at ages 18-44 years were identified in the Swedish Cancer Register, with information on childbirths from the Swedish Multi-Generation Register and clinical data from Breast Cancer Quality Registers. Each woman with PrBC or PPBC was matched 1 : 2 by age and year to comparators diagnosed with breast cancer not near pregnancy. Distributions of stage, grade, and surrogate subtypes were compared. Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for breast cancer mortality were estimated using Cox regression.

RESULTS

We identified 1430 women with PrBC and PPBC (181 during pregnancy, 499 during the first and 750 during the second year after delivery). Compared to 2860 comparators, women with PrBC and PPBC in the first year after delivery had a significantly higher proportion of luminal human epidermal growth factor receptor 2 (HER2)-positive, HER2-positive and triple-negative tumours, and more advanced stage at diagnosis. After adjustment for age, year, parity, country of birth, hospital region, subtype, and stage, women diagnosed during the second trimester had a worse prognosis than matched comparators (HR 1.8, 95% CI: 1.0-3.2).

CONCLUSIONS

Women diagnosed during pregnancy or within the first year after delivery have a worse prognosis than women diagnosed not near pregnancy due to adverse tumour biology and advanced stage at diagnosis. A worse prognosis for women diagnosed during the second trimester remained after multivariable adjustment, possibly reflecting difficulties to provide optimal treatment during ongoing pregnancy.

Immune microenvironment dynamics in breast cancer during pregnancy: impact of gestational age on tumor-infiltrating lymphocytes and prognosis

Background

Breast cancer during pregnancy (PrBC) is a rare condition known for its aggressive clinical behavior. The presence of tumor-infiltrating lymphocytes (TILs) has been shown to have a significant impact on the prognosis of these patients. Despite some biological characteristics of the tumor that may differ depending on the gestational age, little is known about the dynamics of the immune landscape within the tumor microenvironment (TME) in PrBC. Therefore, in this study, our objective was to gain comprehensive insights into the relationship between gestational age at breast cancer diagnosis and the composition of the TME.

Methods

n = 108 PrBC were selected from our institutional registry and categorized based on the gestational age by trimester. For all cases, TILs were profiled according to the International TILs Working Group recommendations, and subtyped by CD4, CD8, and forkhead box P3 (FOXP3) immunohistochemistry. PD-L1 was tested according to the combined positive score (CPS) using the IHC 22C3 pharmDx assay, with a cutoff value of ≥10 for positivity. The statistical approach encompassed Fisher's and Chi-squared tests, with appropriate adjustments for multiple comparisons, logistic regression models, and survival analyses based on the Kaplan-Meier method.

Results

The proportion of patients with poorly differentiated (G3) neoplasms increased as the gestational age advanced (first trimester, n = 25, 56.8%; second trimester, n = 27, 69.2%; third trimester, n = 21, 87.5%; p = 0.03). The histologic subtypes as well as the hormone receptor (HR) and HER2 status did not show significant changes across different pregnancy trimesters. In the HR+/HER2- subtype, there was a higher proportion of tumors with high/moderate TILs in the early phases of pregnancy, similar to FOXP3 expression (TILs: first trimester, n = 10, 35.7%; second trimester, n = 2, 10.5%; third trimester, n = 0; p = 0.02; FOXP3: first trimester, n = 10, 40%; second trimester, n = 3, 15.8%; third trimester, n = 0; p = 0.03). The median follow-up for our cohort was 81 months. Patients who relapsed after a breast cancer diagnosis during the first trimester were more frequently PD-L1-negative, unlike those with no disease recurrence (n = 9, 100% vs. n = 9, 56.3%; p = 0.03; hormone therapy and n = 9, 100% vs. n = 7, 53.9%; p = 0.02; chemotherapy). No statistically significant differences were seen among the three trimesters in terms of survival outcome.

Conclusion

The TME dynamics of HR+/HER2- PrBC vary based on gestational age, suggesting that immune tolerance expression during later gestational age could explain the increased aggressiveness of tumors diagnosed at that stage.

Clinicopathologic features, treatment, and prognosis of pregnancy-associated breast cancer

Purpose

To identify the clinicopathological features, treatment, and prognosis of patients with breast cancer, who were diagnosed during and after pregnancy.

Methods

We searched for patients with pregnancy-associated breast cancer (PABC) using the big data query and analysis system of Peking Union Medical College Hospital from between January 1, 2013, and December 31, 2021, and matched each patient with two non-PABC patients by age at diagnosis, year at diagnosis, and tumor stage. The clinicopathologic features, treatment, and outcomes of breast cancer during pregnancy (BC-P) and breast cancer during the first-year post-partum (BC-PP) were examined retrospectively in two case-control studies.

Results

Eighteen BC-P cases, 36 controls for BC-P cases, 62 BC-PP cases, and 124 controls for BC-PP cases were enrolled in our study. The expression of HER-2 and Ki-67 was higher in BC-PP cases than in its controls (P=0.01, 0.018, respectively). Patients with BC-PP were more likely to choose mastectomy than breast-conserving surgery (P=0.001). There were no significant differences in event-free survival (EFS) between patients with BC-P and BC-PP and their controls.

Conclusion

BC-P and BC-PP patients displayed adverse clinicopathological features in our population. However, when matched by age at diagnosis, year of diagnosis, and tumor stage, BC-P and BC-PP patients did not show inferior outcomes to controls, probably due to aggressive multimodality therapy.