This was a retrospective descriptive study conducted over a four-year period, from January 1, 2021, to December 31, 2024, at the Department of Medical Oncology, Hassan II University Hospital, Fez, Morocco.

All patients diagnosed with breast cancer during pregnancy or within one year postpartum and managed at Hassan II University Hospital between January 2021 and December 2024 were eligible for inclusion. Breast cancer cases diagnosed during the postpartum period were systematically searched in the department records. No cases diagnosed within one year after delivery were identified during the study period, explaining their absence from the final series.

Confirmed pregnancy at the time of breast cancer diagnosis.Histologically confirmed diagnosis of breast cancer.Availability of a complete medical record.

Patients diagnosed with breast cancer prior to pregnancy.Incomplete or non-exploitable medical records.

Data were extracted from hospital medical records and included:

Epidemiological data: age, parity, family history of cancer, gestational age at diagnosis.Clinical data: presenting symptoms, consultation delay, tumor size, presence of inflammatory signs or lymphadenopathy.Paraclinical data: breast imaging, staging investigations, histopathological profile, hormone receptor status, HER2 status, and molecular subtype.Therapeutic data: surgery, chemotherapy, radiotherapy.Outcome and follow-up: recurrence and survival.

Data were entered and analyzed using SPSS software version 26. Quantitative variables were expressed as mean ± standard deviation or median, depending on data distribution. Qualitative variables were presented as frequencies and percentages. Due to the limited sample size, no comparative or multivariate analyses were performed.

The study was approved by the Ethics Committee of Hassan II University Hospital, Fez. All patients were managed in accordance with the principles of the Declaration of Helsinki, with strict respect for data confidentiality.

The twelve included patients accounted for 3.1% of the 387 breast cancer patients managed in the department during the study period. The mean age was 35 years, and 57% of the patients were multiparous. Breast cancer was diagnosed during pregnancy in all cases (100%), with a mean gestational age of 20 weeks of amenorrhea.

The main mode of presentation was self-detection of a breast lump, reported in 70% of patients, with a mean consultation delay of 4 months (Table 1).

Table 1. Epidemiological and clinical characteristics of the patients (n = 12).

Bilateral breast involvement was observed in two cases. The mean tumor size was 30 mm. Local inflammatory signs were present in 50% of patients, and suspicious axillary lymphadenopathy was identified in 33% of cases. Metastatic disease at diagnosis was found in 16.7% of patients, predominantly involving bone metastases. Regarding the histopathological profile, invasive carcinoma of no special type (NST) accounted for 95% of cases, with SBR grade II - III tumors observed in 85%. Hormone receptors (ER/PR) were negative in 50% of patients, HER2 overexpression was detected in 25%, and the triple-negative subtype was identified in 16.7% of cases (Table 2).

Table 2. Tumor characteristics and histopathological features.

Regarding the diagnostic work-up, breast ultrasound was performed in all patients and represented the first-line imaging modality. Mammography with abdominal shielding was performed in selected cases when clinically indicated. Histological confirmation was obtained by core needle biopsy in all cases. Biopsy was performed at the time of clinical suspicion, regardless of gestational age, allowing diagnosis during pregnancy, with most cases identified during the second trimester. The physiological breast changes associated with pregnancy, combined with delayed consultation, contributed to the diagnostic delay observed in our series.

Based on the TNM classification, most tumors corresponded to locally advanced disease, with a predominance of T2 lesions and frequent clinical axillary lymph node involvement. Bilateral breast involvement was uncommon. Metastatic disease at diagnosis was limited but present, mainly involving bone metastases.

The initial staging work-up was adapted to pregnancy to minimize fetal exposure to ionizing radiation and relied on clinical examination, breast and axillary ultrasound, chest radiography with abdominal shielding, and liver ultrasound. Abdominopelvic ultrasound was performed as part of routine obstetric follow-up. High-radiation imaging modalities, such as computed tomography and bone scintigraphy, were avoided during pregnancy and deferred to the postpartum period when required. Overall, most non-metastatic patients were diagnosed at advanced clinical stages, predominantly stage II or III.

All patients received multidisciplinary management, involving medical oncologists, surgeons, and obstetricians, in order to reconcile oncological treatment with pregnancy monitoring.

Operability assessment: Tumors were deemed operable in 10 out of 12 cases.Breast surgery: Performed in 83% of patients (10/12), including 6 mastectomies and 4 lumpectomies, chosen according to tumor size, location, and gestational age, in close coordination with the obstetrician. Axillary dissection was performed depending on nodal involvement.Chemotherapy: All patients received chemotherapy:Neoadjuvant: 6 cases (50%)Adjuvant: 4 cases (33.3%)Palliative: 2 cases (16.7%)

Chemotherapy regimens were primarily anthracycline-based, consisting of doxorubicin or epirubicin combined with cyclophosphamide (AC or EC protocols), administered every three weeks. In patients requiring sequential therapy, taxanes (mainly paclitaxel) were introduced after completion of anthracyclines when gestational age allowed. Systemic treatment was initiated after the first trimester in all cases, predominantly during the second trimester, in accordance with international recommendations to minimize teratogenic risk. No major treatment delays or significant dose reductions were reported during pregnancy. No severe maternal toxicity was observed, and no treatment discontinuation was required. Fetal monitoring was conducted regularly through coordinated obstetric follow-up, with no immediate complications attributable to in utero exposure to chemotherapy. In the postpartum period, treatment was completed or intensified according to tumor subtype. Patients with HER2-positive tumors received anti-HER2 therapy (trastuzumab) after delivery. Endocrine therapy was initiated postpartum in hormone receptor–positive patients, mainly with tamoxifen, following completion of chemotherapy and radiotherapy when indicated.

Radiotherapy: No patient received radiotherapy during pregnancy.Obstetric follow-up and coordination: Regular ultrasound monitoring, assessment of fetal well-being, and adjustment of treatments according to maternal tolerance. Therapeutic decisions were discussed in multidisciplinary tumor board meetings.Additional measures: Psychological support, counseling on delayed breastfeeding, and postpartum planning of complementary treatments (radiotherapy or hormonal therapy when indicated).

Obstetrical outcomes were favorable in the majority of cases. The mean gestational age at delivery was 37 weeks, with most deliveries occurring at or beyond 37 weeks of gestation. Vaginal delivery was achieved in the majority of patients, while cesarean section was performed for obstetrical indications. Birth weights were appropriate for gestational age. Apgar scores at 5 minutes were satisfactory in all newborns. Two neonates (16.7%) required short-term admission to the neonatal intensive care unit due to prematurity. No congenital malformations or major growth restrictions were reported.

All patients who received chemotherapy during pregnancy were treated after the first trimester, predominantly during the second and third trimesters. No immediate neonatal complications were directly attributable to in utero exposure to chemotherapy.

The mean follow-up duration was 18 months. During follow-up, disease recurrence was observed in six patients (50%). Recurrences were categorized as locoregional when involving the ipsilateral breast or regional lymph nodes (10%), contralateral breast recurrence (20%), and distant metastasis (20%). Distant relapse represented a significant proportion of recurrence events (Figure 1).

Figure 1.Disease course of patients with pregnancy-associated breast cancer.

Disease-free survival (DFS) was defined as the time from initial diagnosis to the first documented recurrence (locoregional, contralateral, or distant) or last follow-up. Overall survival (OS) was defined as the time from diagnosis to death from any cause or last follow-up. At the time of analysis, the estimated disease-free survival rate was 50%, while the overall survival rate was 83.3%, with two deaths occurring in patients presenting with advanced-stage disease at diagnosis.