Bwanga Alick¹*, Lunkamba Gabriel², Tembo Penias¹, Banda Chihena^3,4, Kapai Titus¹, Banda Edward¹, Muzyanba Himubali³, Songwe Mupeta¹, Njovu Chuma⁵, Ngalamika Owen^6
1 University Teaching Adult Hospital, Lusaka, Zambia
² Cancer Diseases Hospital, Lusaka, Zambia
³ Surgery Department, School of Medicine, University of Zambia, Lusaka, Zambia
⁴ Plastic and Reconstructive Surgery Unit, Department of Surgery, University Teaching Adult Hospital, Lusaka, Zambia
⁵ Stellenbosch University, Cape Town, South Africa
⁶ Medicine Department, School of Medicine, University of Zambia, Lusaka, Zambia

Corresponding author: Bwanga Alick

DOI: https://doi.org/10.55320/mjz.53.3.1151

Keywords: Bilateral breast cancer; Case report; Modified radical mastectomy; Neoadjuvant chemotherapy; Radiotherapy access; Synchronous; Triple-negative breast cancer

A 39-year-old premenopausal woman presented after approximately one year of bilateral breast lumps and was diagnosed with synchronous bilateral invasive carcinoma of no special type with a triple-negative phenotype (ER-negative, PR-negative and HER2-negative) and Ki-67 indices of 45-50%. Clinical/radiological staging was cT4a cN1 M0 (stage IIIB) on the right and cT2 cN1 M0 (stage IIB) on the left. She completed six cycles of neoadjuvant carboplatin plus paclitaxel, with an estimated partial response of approximately 60%, followed by bilateral modified radical mastectomy and level II axillary lymph-node dissection. Postmastectomy histology confirmed residual invasive carcinoma; margins were negative on the left but positive at the superior and posterior margins on the right. A pathological complete response was therefore not achieved. Postmastectomy radiotherapy was recommended but could not be delivered because it was unavailable at the treating facility and access elsewhere was financially constrained. At one month she was clinically well; at six months the available record documented good recovery without new adverse events, although no interval imaging or laboratory surveillance was recorded. This case highlights the clinical complexity of synchronous bilateral triple-negative breast cancer and the consequences of gaps in genetic testing, systemic treatment options and radiotherapy access in resource-limited settings.

Bilateral breast cancer (BBC), defined by primary invasive carcinoma involving both breasts, is uncommon and may present synchronously or metachronously. Synchronous disease is generally defined by diagnosis of the contralateral primary within approximately 3-6 months of the first tumour.^{[1] [2]} The burden of breast cancer is increasing in many low- and middle-income countries, where delayed presentation, limited screening, diagnostic constraints and treatment-resource gaps contribute to advanced-stage disease.^{[3] [4]}

Triple-negative breast cancer (TNBC) is defined by lack of oestrogen receptor (ER), progesterone receptor (PR) and HER2 expression. It accounts for approximately 10-20% of breast cancers and is characterised by aggressive biology, a relatively high risk of early recurrence and fewer biomarker-directed treatment options than hormone receptor-positive or HER2-positive disease.

We report synchronous bilateral TNBC in a 39-year-old premenopausal woman with markedly asymmetric tumour burden and advanced right-sided disease. The case is clinically instructive because it combines bilateral aggressive tumour biology, residual disease after neoadjuvant chemotherapy, positive right-sided surgical margins and important limitations in access to genetic testing, immunotherapy, PARP inhibition and postmastectomy radiotherapy.

A 39-year-old woman, gravida 3 para 3, with tertiary education, presented with bilateral breast lumps. She was married with three children, all of whom she had breastfed. Her first pregnancy and delivery occurred at 27 years of age. She reported no smoking or alcohol use, no contraceptive use, no significant past medical or surgical history and no known family history of breast, ovarian or other cancer suggestive of a hereditary breast/ovarian cancer syndrome. The breast lumps had first been noticed approximately one year before presentation. The right lump was considerably larger and slowly progressive. She reported no breast pain, nipple discharge or skin changes and denied constitutional symptoms. Her Eastern Cooperative Oncology Group (ECOG) performance status was 0.

On examination, the right breast contained a large fixed mass measuring approximately 15 × 10 cm with nipple retraction and extension toward the ipsilateral axilla. The left breast contained a mobile 2 × 1 cm mass and no palpable left axillary lymphadenopathy. The source clinical note did not separately document peau d’orange, ulceration, inflammatory change, skin tethering, chest-wall fixation or supraclavicular nodal findings. Thus, these specific examination features cannot be reliably inferred from the available record.

Core-needle biopsies were obtained from both breast masses. Computed tomography (CT) of the chest and abdomen showed a heterogeneous right breast mass of approximately 18 cm with dystrophic nodular calcification and ipsilateral level I axillary lymphadenopathy. The left breast mass measured approximately 3 cm, with level I axillary lymphadenopathy on CT. No distant metastases were identified. The apparent discrepancy on the left is therefore explained by radiological nodal involvement in the absence of clinically palpable left axillary nodes.

Histopathological examination of both core biopsies confirmed invasive carcinoma of no special type (NST). Immunohistochemistry showed a triple-negative phenotype in both tumours (ER-negative, PR-negative and HER2-negative), with Ki-67 proliferative indices of approximately 45-50%. Based on the clinical and radiological findings, the treating team assigned cT4a cN1 M0 (stage IIIB) to the right breast and cT2 cN1 M0 (stage IIB) to the left breast.

The patient completed six cycles of neoadjuvant carboplatin plus paclitaxel. The treating record described treatment on a three-weekly cycle and documented an estimated partial response of approximately 60%. Exact carboplatin area-under-the-curve (AUC) and paclitaxel mg/m² doses were not retrievable from the case record available for this report. Three blood transfusions were required for haematological support during chemotherapy. No additional significant adverse events, treatment-related hospital admissions, dose reductions, delays or omissions were documented in the available record; however, laboratory toxicity grades and details regarding neutropenia, thrombocytopenia, neuropathy, infection, alopecia and nausea/vomiting were not recorded in the manuscript source data.

After neoadjuvant chemotherapy, the patient underwent bilateral modified radical mastectomy with level II axillary lymph-node dissection. Recovery was uncomplicated and she was discharged on postoperative day 3. The postoperative pathology summary available for this case documented residual invasive ductal carcinoma in both mastectomy specimens. The left breast margins were negative. The right breast had positive superior and posterior margins. Residual invasive disease bilaterally confirms that a pathological complete response was not achieved. The available pathology summary did not provide residual tumour dimensions, histological grade, lymphovascular invasion status, lymph-node yield, number of positive nodes, extranodal extension or sufficient data to assign ypTNM stage or calculate residual cancer burden. These unavailable pathology variables are acknowledged as a limitation of the report.

Postmastectomy radiotherapy was recommended, particularly because of the advanced right-sided presentation, nodal disease and positive right-sided margins. Radiotherapy was unavailable at the treating facility, and access to treatment elsewhere was financially constrained. Additional adjuvant systemic therapy was discussed. At the one-month postoperative review, the patient was clinically well and had no surgical complications. At six months, the available follow-up record documented good recovery and no new adverse events, but it did not record interval imaging, laboratory surveillance or a formal radiological recurrence assessment, and no documentation confirming initiation of adjuvant radiotherapy or capecitabine was available.

The patient reported substantial relief after completing chemotherapy and bilateral mastectomy and described a reduction in anxiety after treatment. She acknowledged the physical and psychological difficulty of losing both breasts but felt that preoperative counselling helped her prepare for the change in body image. She remained optimistic about recovery and returning to her usual activities. She was, however, concerned that the recommended radiotherapy was not readily accessible despite having completed intensive chemotherapy and surgery.

This case illustrates synchronous bilateral TNBC in a young premenopausal woman, with substantially more advanced disease in the right breast. Synchronous bilateral breast cancer is uncommon and is clinically challenging because each breast may differ in stage, histology and receptor profile; treatment planning must therefore account for the biology and stage of each primary tumour.^{[5] [6]}

TNBC is characterised by absence of ER, PR and HER2 expression and tends to have a higher proliferative rate, earlier recurrence and poorer prognosis than many hormone receptor-positive breast cancers. The Ki-67 indices of 45-50% in both tumours in this patient are consistent with a highly proliferative phenotype.^[6]

The advanced right-sided stage after approximately one year of symptoms reflects a recognised challenge in sub-Saharan Africa, where delays in diagnosis and limitations in screening, pathology, imaging and oncology services may contribute to presentation with larger tumours and nodal disease.^{[3] [13]}

Neoadjuvant systemic therapy is central to the management of high-risk and locally advanced TNBC. The treating team initially considered a KEYNOTE-522-style chemo-immunotherapy approach, but pembrolizumab was unavailable and full pre-anthracycline work-up was constrained. The patient therefore received a platinum-taxane regimen, completing six cycles and achieving an estimated 60% partial response.^{[8] [9] [10] [11]}

The need for three blood transfusions illustrates the supportive-care burden associated with intensive chemotherapy in resource-constrained settings. Because the source chemotherapy chart was not available to the authors at the time of revision, exact drug doses, toxicity grades and dose-modification data could not be reported; this limits reproducibility of the treatment description and should be recognised when interpreting the case.

Bilateral modified radical mastectomy with axillary dissection was undertaken after neoadjuvant therapy. Importantly, residual invasive carcinoma remained in the right breast, and the right mastectomy specimen had positive superior and posterior margins. These findings indicate persistent high locoregional risk and strengthen the indication for postmastectomy radiotherapy. The absence of detailed nodal counts and other postoperative pathological variables prevents assignment of ypTNM stage and residual cancer burden, which are important prognostic measures.

The patient’s age and TNBC phenotype also raise important hereditary-cancer considerations. Contemporary genetic-risk guidance supports germline assessment in young patients with TNBC, but genetic counselling and BRCA1/2 testing were unavailable.^[12] This limitation not only restricts familial risk counselling but may also affect eligibility for adjuvant PARP inhibition in patients with germline BRCA1/2-mutated, HER2-negative high-risk early breast cancer.^[17]

Radiotherapy access was a major system-level limitation in this case. Postmastectomy radiotherapy improves locoregional control in appropriately selected node-positive and high-risk breast cancers, and its role was particularly relevant here because of the advanced right-sided disease and positive margins.^{[14] [15]} The inability to deliver recommended radiotherapy therefore represents a clinically meaningful gap rather than a minor variation in care.

For patients with HER2-negative residual invasive disease after neoadjuvant chemotherapy, CREATE-X demonstrated improved disease-free and overall survival with adjuvant capecitabine, with particular relevance to the TNBC subgroup.^[16] Capecitabine was considered in this patient, but subsequent treatment documentation was incomplete. Together with the lack of pembrolizumab, germline testing, PARP inhibitors and radiotherapy, this illustrates how multiple resource constraints may compound risk even when surgery and cytotoxic chemotherapy are available.

Published reports also show that synchronous bilateral breast cancer is heterogeneous rather than a single clinicopathological entity. A Nigerian series described premenopausal women with bilateral breast cancer and triple-negative immunophenotypes, including synchronous disease, while other international case reports demonstrate discordant receptor biology between the two breasts.^{[13] [18] [19]} These reports support careful bilateral pathological characterisation and avoidance of broad assumptions that both tumours necessarily share the same biology or prognosis.

Table 1: Clinical Timeline and Outcomes

Table 2: Selected Published Reports Relevant to Synchronous Bilateral Breast Cancer and TNBC

This case describes synchronous bilateral TNBC in a 39-year-old premenopausal woman with advanced right-sided disease. Neoadjuvant carboplatin and paclitaxel produced a clinically meaningful partial response and enabled bilateral modified radical mastectomy, but residual invasive disease remained unilaterally and the right specimen had positive superior and posterior margins. These findings, together with nodal disease, placed the patient at substantial locoregional risk, making the inability to access postmastectomy radiotherapy particularly consequential. The case also demonstrates how incomplete access to genetic testing, immunotherapy, PARP inhibitors and complete pathology reporting can limit risk stratification and treatment planning. Strengthening comprehensive breast cancer services, including pathology, genetic assessment, systemic therapies and radiotherapy, is essential to improve outcomes in resource-limited settings.

Conflict of interest

None declared.

ETHICAL ISSUES / CONSENT: Informed consent for publication of the clinical details contained in this case report was obtained from the patient.

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