Prognosis of triple-negative breast cancer associated with pregnancy: A propensity score-matched analysis from the French CALG (Cancer Associé à la Grossesse) network

Outcomes of patients treated with chemotherapy for breast cancer during pregnancy compared with nonpregnant breast cancer patients treated with systemic therapy

INTRODUCTION

Prior studies of patients treated for breast cancer during pregnancy (PrBC) report mixed outcomes and are limited by substandard treatment, small cohorts, and short follow-up. This study compared survival outcomes of PrBC patients treated with chemotherapy during pregnancy with nonpregnant patients matched by age, year of diagnosis, stage, and subtype.

METHODS

PrBC patients treated from 1989 to 2022 on prospective institutional protocols were eligible. Disease-free survival (DFS), overall survival (OS), and progression-free survival (PFS) were estimated using the Kaplan-Meier method and multivariable Cox proportional hazards regression.

RESULTS

Among 143 PrBC and 285 nonpregnant patients, median follow-up was 11.4 years. Survival differences were statistically significant, with median DFS and OS not attained for PrBC patients versus 5.6 years (95% confidence interval [CI], 3.6-15.4; p = .0001) and 19.3 years (95% CI, 14.1-not estimated; p = .0262) for nonpregnant patients, respectively. Median PFS was 24.1 years (95% CI, 15.8-not estimated) for PrBC patients versus 8.4 years (95% CI, 6.4-10.9) for the nonpregnant cohort (p = .0008). Study cohort was associated with DFS, PFS, and OS in multivariable analyses, with the nonpregnant cohort having increased risks of disease recurrence (hazard ratio [HR], 1.91; 95% CI, 1.33-2.76; p = .0005) and disease progression or death (HR, 1.68; 95% CI, 1.19-2.39; p = .0035), and shorter OS (HR, 1.52; 95% CI, 1.01-2.29; p = .0442).

CONCLUSION

These data suggest that PrBC patients treated with chemotherapy during pregnancy have at least comparable, if not superior, outcomes than nonpregnant patients with similar age, cancer stage, and subtype. Analyses excluding patients with postpartum breast cancer were unable to be performed and are a priority for future confirmatory studies.

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.

ESMO Expert Consensus Statements on the management of breast cancer during pregnancy (PrBC)

The management of breast cancer during pregnancy (PrBC) is a relatively rare indication and an area where no or little evidence is available since randomized controlled trials cannot be conducted. In general, advances related to breast cancer (BC) treatment outside pregnancy cannot always be translated to PrBC, because both the interests of the mother and of the unborn should be considered. Evidence remains limited and/or conflicting in some specific areas where the optimal approach remains controversial. In 2022, the European Society for Medical Oncology (ESMO) held a virtual consensus-building process on this topic to gain insights from a multidisciplinary group of experts and develop statements on controversial topics that cannot be adequately addressed in the current evidence-based ESMO Clinical Practice Guideline. The aim of this consensus-building process was to discuss controversial issues relating to the management of patients with PrBC. The virtual meeting included a multidisciplinary panel of 24 leading experts from 13 countries and was chaired by S. Loibl and F. Amant. All experts were allocated to one of four different working groups. Each working group covered a specific subject area with two chairs appointed: Planning, preparation and execution of the consensus process was conducted according to the ESMO standard operating procedures.

Overall survival is the lowest among young women with postpartum breast cancer

BACKGROUND

Women diagnosed with breast cancer prior to age 45 years (<45y) and within the first 5 years postpartum (postpartum breast cancer, PPBC) have the greatest risk for distal metastatic recurrence.

METHODS

Pooling data from the Colorado Young Women Breast Cancer cohort and the Breast Cancer Health Disparities Study (N = 2519 cases), we examined the association of parity, age, and clinical factors with overall survival (OS) of breast cancer over 15 years of follow-up.

RESULTS

Women with PPBC diagnosed at <45y had the lowest OS (p < 0.0001), while OS of nulliparous cases diagnosed at <45y did not differ from OS of cases diagnosed at 45-65y regardless of parity status. After adjustment for study site, race/ethnicity, clinical stage, year of diagnosis and stratification for oestrogen receptor status, PPBC remained an independent factor associated with poor OS. Among cases diagnosed at <45y, nulliparous cases had 1.6 times better OS (hazard ratio (HR) = 0.61, 95%CI 0.42-0.87) compared to those with PPBC, with a more pronounced survival difference among stage I breast cancers (HR = 0.30, 95%CI 0.11-0.79). Among very young women diagnosed at age ≤35y, nulliparous cases had 2.3 times better OS (HR = 0.44, 95%CI 0.23-0.84) compared to PPBC.

CONCLUSION

Our results suggest that postpartum status is the main driver of poor prognosis in young women with breast cancer, with the strongest association in patients diagnosed at age ≤35y and in those with stage I disease.