Dermot’s Diary #9

October is Breast Cancer Awareness Month, and everybody’s wearing pink. Even the trees – we’ve seen pink ribbons tied around trees outside some oncology treatment centres in Cape Town.

Breast cancer is top of mind, and the recent introduction of molecular breast cancer testing in Burkina Faso highlights growing access to more personalised care.

Recent developments in cellular and molecular breast cancer diagnostics reflect a strong shift towards dynamic precision oncology, real-time monitoring, and refined classification rather than static, one-time tissue biopsies. Diagnostic tests can now tell us a whole lot more about a patient’s breast cancer.

We are moving beyond asking only, “What type of breast cancer is this?” We can increasingly ask, “What is driving it, which treatments might work, and has the cancer changed since treatment began?”

Traditional pathology is still the starting point. Testing for hormone receptors and HER2 helps to classify the cancer and guide treatment. Molecular tests add another layer by identifying genetic changes that may influence treatment choices.

For example, changes in genes such as PIK3CA and ESR1 can provide useful information in certain advanced breast cancers. Inherited changes in BRCA1 or BRCA2 can also have implications for treatment and for relatives’ cancer risk. The advance is not one test replacing everything else, but different tests answering different clinical questions.

Would a patient need testing more than once? Breast cancer can change during treatment, so how is molecular testing helping clinicians recognise resistance, particularly when hormone treatment stops working?

We know that a tumour is not necessarily biologically identical throughout a patient’s illness. Treatment can favour the survival of cancer cells with changes that help them to escape its effects. A sample taken at diagnosis may not tell the whole story several years later.

For example, certain ESR1 mutations (ESR1 is a gene involved in the oestrogen receptor) can emerge during treatment and help to explain resistance to some hormone therapies. Identifying these changes can help to guide the next treatment choice in advanced disease.

Repeat testing means you can reassess the cancer when the result could change management. We’ve recently inked a deal with Diatech Pharmacogenetics, which lists ESR1 and PIK3CA among the targets available through its EasyPGX assay portfolio, including liquid-biopsy applications.

Liquid biopsy could be a game changer. It’s often described as a major advance in cancer care. Where does it already add practical value in breast cancer, and what are its limitations?

A liquid biopsy can look for fragments of tumour DNA circulating in the blood. In some patients with advanced breast cancer, this can help to identify genetic changes relevant to treatment without requiring another invasive tissue biopsy. It also offers a practical way to reassess tumour biology over time.

But we need to remember that a negative blood result does not necessarily mean that a mutation is absent. There may be too little tumour DNA in the sample for the test to detect it. Tissue testing may still be needed when the blood result is uninformative.

So liquid biopsy adds to tissue-based diagnosis rather than making it obsolete. AmoyDx, for example, lists a breast cancer NGS panel compatible with both tumour tissue and plasma.

Diatech’s portfolio includes EasyPGX and Myriapod. How do these two approaches complement one another, and how should a laboratory decide which to use?

The choice starts with the clinical question. Targeted PCR testing looks for a defined set of genetic changes. It can be useful when a clinician needs an answer about a particular treatment-related marker. Diatech’s EasyPGX portfolio includes breast cancer assays for PIK3CA and ESR1.

Next-generation sequencing, or NGS, examines multiple genetic targets together. It can be useful when the question is broader or several possible alterations need investigating. Diatech’s Myriapod range uses this approach, with panels covering different clinical needs.

The technologies are complementary, not a simple hierarchy in which the broader test is always better. The appropriate choice depends on the information needed, the sample available and whether the findings can guide care.

What will turn these innovations into better care across Africa? One can supply a new assay or platform, but we need to ensure that it changes patient care rather than simply expands laboratory capability.

The starting point should be a clinical decision, not a technology purchase. Breast cancer tests answer different questions: some establish hormone-receptor or HER2 status, while others identify mutations associated with treatment selection or inherited risk. A useful service connects the right question to the right test.

That creates practical questions about laboratory training, reliable supplies, quality assurance, turnaround time and clear reporting. It also raises a crucial access question: can the patient obtain the treatment that the result points towards?

In breast cancer, clinical management has shifted heavily from basic immunohistochemistry to molecular profiling for targeted therapy selection, endocrine resistance monitoring, and hereditary/homologous recombination risk. Celtic’s TruPCR, AmoyDx and newly added Diatech offerings of complementary PCR- and NGS-based tools for molecular testing fit into that pathway.