Concurrent human epidermal growth factor receptor 2-positive breast cancer with axillary nodal metastasis in a patient with pituitary prolactinoma: a case report

Published on Wednesday, 26 August 2026

Abstract

Background: Managing high-risk human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) concurrent with a functioning pituitary adenoma is clinically challenging. Current oncological guidelines lack specific clinical consensus protocols regarding the simultaneous administration of intensive dual-HER2 targeted therapy, tyrosine kinase inhibitors (TKIs), and continuous dopamine agonists.

Case description: A 56-year-old postmenopausal woman with a 5-year history of pituitary prolactinoma presented with a painless left breast mass over a 2-year duration. Her serum prolactin (PRL) was strictly pharmacologically controlled within the normal physiological range (8-15 ng/mL). Diagnostic breast magnetic resonance imaging (MRI) revealed a suspicious 3 mm × 5 mm spiculated nodule [Breast Imaging Reporting and Data System (BI-RADS) 4a]. She initially underwent an excisional biopsy which confirmed invasive carcinoma. Due to intraoperative sentinel lymph node positivity, the tumor's proximity to the nipple, and the patient's explicit refusal of breast conservation, she underwent a left modified radical mastectomy. Definitive surgery demonstrated a pathologically paradoxical finding: a minute 0.8 cm (pT1b) invasive ductal carcinoma accompanied by early axillary lymph node metastasis (pN1a, 2/27 positive nodes). The tumor exhibited high proliferative potential (Ki-67 40%) and parallel HER2 amplification (3+) in both the invasive and the high-grade ductal carcinoma in situ (DCIS) components. Adhering to a multidisciplinary plan while maintaining her cabergoline regimen uninterrupted, she received adjuvant chemotherapy, dual anti-HER2 blockade (trastuzumab and pertuzumab), and radiotherapy. She declined extended adjuvant neratinib due to gastrointestinal toxicity concerns. She remains completely disease-free at 36 months post-surgery with stable pituitary function.

Conclusions: This case underscores the ongoing safety, feasibility, and practical compatibility of integrating dopamine agonists with intensive BC therapies. Furthermore, the paradoxical early lymphatic dissemination of a sub-centimeter primary tumor under physiological PRL levels suggests profound local crosstalk between HER2 and PRL receptor (PRLR) signaling. This necessitates vigilant management of even small, highly proliferative lesions in patients with concurrent endocrine comorbidities.

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About this publication.

The Di Bella's Method: Use of prolactin inhibitors Cabergoline and/or Bromocriptine, Melatonin (since 1974), Retinoids (40mg per day Beta-Carotene, 10mg per day ATRA and 10mg per day Axerophthol palmitate), Estrogen therapy (Anastrozole 1 mg tab per day), pseudo-Metronomic Chemotherapy Cyclophosphamide and/or Hydroxyurea with Somatostatin/Octreotide analogues and/or derivatives (since 1977) together with others chemical compounds) in Breast Cancer (the dosage and administration schedule must be individualised for each patient):

- A retrospective observational clinical study of triple negative breast cancer cases treated with Di Bella Method: A preliminary data;

- The Synergism of Somatostatin, Melatonin, Vitamins Prolactin and Estrogen Inhibitors Increased Survival, Objective Response and Performance Status In 297 Cases of Breast Cancer;

- Complete objective response, stable for 5 years, with the Di Bella Method, of multiple-metastatic carcinoma of the breast;

- Evaluation of the safety and efficacy of the first-line treatment with somatostatin combined with melatonin, retinoids, vitamin D3, and low doses of cyclophosphamide in 20 cases of breast cancer: a preliminary report;

- The Di Bella Method (DBM) improved survival, objective response and performance status in a retrospective observational clinical study on 122 cases of breast cancer;

- Complete objective response to biological therapy of plurifocal breast carcinoma;

- The Di Bella Method (A Fixed Part - Bromocriptine and/or Cabergoline);

- Prolactin inhibitors in oncology - In vitro, review and in vivo publications;

- The Di Bella Method (A Fixed Part - Cyclophosphamide 50mg tablets and/or Hydroxyurea 500mg tablets, one or two per day);

- The Di Bella Method (A Fixed Part - Somatostatin, Octreotide, Sandostatin LAR, analogues and/or derivatives since 1977);

- Somatostatin in oncology, the overlooked evidences - In vitro, review and in vivo publications;

- Publication, 2018 Jul: Over-Expression of GH/GHR in Breast Cancer and Oncosuppressor Role of Somatostatin as a Physiological Inhibitor (from Di Bella's Foundation);

- Publication, 2018 Sep: The over-expression of GH/GHR in tumour tissues with respect to healthy ones confirms its oncogenic role and the consequent oncosuppressor role of its physiological inhibitor, somatostatin: a review of the literature (from Di Bella's Foundation);

- Publication, 2019 Aug: The Entrapment of Somatostatin in a Lipid Formulation: Retarded Release and Free Radical Reactivity (from Di Bella's Foundation);

- Publication, 2019 Sep: Effects of Somatostatin and Vitamin C on the Fatty Acid Profile of Breast Cancer Cell Membranes (from Di Bella's Foundation);

- Publication, 2019 Sep: Effects of somatostatin, curcumin, and quercetin on the fatty acid profile of breast cancer cell membranes (from Di Bella's Foundation);

- Publication, 2020 Sep: Two neuroendocrine G protein-coupled receptor molecules, somatostatin and melatonin: Physiology of signal transduction and therapeutic perspectives (from Di Bella's Foundation);

The Di Bella's Method: Use of Prolactin Inhibitors Cabergoline and/or Bromocriptine, Somatostatin/Octreotide analogues and/or derivatives since 1977 associated with pseudo-Metronomic Chemotherapy Cyclophosphamide and/or Hydroxyurea - together with others chemical compounds: the dosage and administration schedule must be individualised for each patient - in several Oncological Pathologies:

- A retrospective observational study on cases of anaplastic brain tumors treated with the Di Bella Method: A rationale and effectiveness;

- Recurrent Glioblastoma Multiforme (grade IV – WHO 2007): a case of complete objective response achieved by means of the concomitant administration of Somatostatin and Octreotide – Retinoids – Vitamin E – Vitamin D3 – Vitamin C – Melatonin – D2 R agonists (Di Bella Method – DBM) associated with Temozolomide;

- The Di Bella Method DBM improved survival objective response and performance status in a retrospective observational clinical study on 23 tumours of the head and neck;

- Chronic Lymphocytic Leukemia: Long-Lasting Remission with Combination of Cyclophosphamide, Somatostatin, Bromocriptine, Retinoids, Melatonin, and ACTH;

- Somatostatin, retinoids, melatonin, vitamin D, bromocriptine, and cyclophosphamide in advanced non-small-cell lung cancer patients with low performance status;

- Somatostatin, retinoids, melatonin, vitamin D, bromocriptine, and cyclophosphamide in chemotherapy-pretreated patients with advanced lung adenocarcinoma and low performance status;

- Observations on the Report of a case of pulmonary adenocarcinoma with lymph node, hepatic and osseus metastasis;

- Pleural Mesothelioma: clinical records on 11 patients treated with Di Bella's Method;

- Malignant pleural mesothelioma, stage T3-T4. Consideration of a case study;

- Excellent result in a Mesothelioma case treated exclusively with Di Bella Method for over 4 years and still treatment with positive results;

- A case of advanced Multiple Myeloma treated with Di Bella Method (DBM) into total remission for 13 years;

- Neuroblastoma: Complete objective response to biological treatment;