This pilot study will test the feasibility of using nanopore sequencing for breast cancer diagnosis in Tanzania. It aims to show that nanopore sequencing is non-inferior to the current standard of care, with the potential for faster and more cost-efficient results. By enhancing the speed and accuracy of diagnosis, this approach could improve treatment planning and outcomes for patients in resource-limited settings.

Excess fresh tissue samples from patients with suspected breast cancer will undergo nanopore sequencing alongside the current standard of care (SoC), which includes histopathology and biomarker analysis for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) status.

Low-pass whole genome sequencing and DNA methylation-based classification will potentially enable the diagnosis of invasive ductal breast cancer in a cost-efficient and highly accurate manner. Additionally, breast cancer subtypes can be determined using methylation signatures and HER2 focal amplification, with results available within hours in a point-of-care setting.

The primary outcome measures are non-inferiority compared to SoC, turnaround time, and overall feasibility. Treatment is not altered due to results of the nanopore sequencing.

Inclusion Criteria:

• Patient with suspected diagnosis of breast cancer undergoing biopsy or surgical resection after specialist consultation as per institutional guidelines
• Excess fresh tumor sample
• Written informed consent

Exclusion Criteria:

• Unable to provide informed consent
• Patients who have already commenced therapy for BC (except for treatment other than biomedicine, e.g. herbal medicines)

All patients with suspected invasive breast cancer undergoing diagnostic workup will be offered to participate.