Breast Cancer Delay Claims: Proving Causation

For solicitors, the decisive question is usually whether the delay made a material difference to the claimant’s stage, treatment, prognosis or overall clinical outcome.

Breast cancer delay claims are easy to oversimplify.

A missed referral, abnormal mammogram or misreported biopsy may establish a credible breach argument. However, breach alone does not prove that the claimant would probably have achieved a better outcome with competent care.

The stronger question is what the cancer would likely have looked like at the point when referral, imaging, diagnosis or treatment should have occurred.

That requires a careful reconstruction of the counterfactual position. Solicitors must consider the likely tumour stage at the point of breach, whether nodal or distant spread had already occurred, what treatment would probably have been offered and how the claimant’s prognosis would have differed.

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Based on practical case studies discussed during INNEG’s webinar, Breast Cancer Delay Claims: Proving Causation, this eBook explores how solicitors can build stronger breast cancer claims through clearer timelines, properly targeted expert evidence and a more precise understanding of tumour biology.

It examines common pathway failures, including delayed GP referral, missed screening abnormalities, mammograms that were not properly reported, biopsies incorrectly classified as benign, results that were not communicated and patients lost to follow-up.

For solicitors, these failures create several distinct questions. Was the cancer visible or diagnosable at the earlier date? What stage was it likely to have reached? Would the treatment have been less extensive? Was metastatic disease already present but occult, or did it probably develop during the negligent delay?

The guide provides a practical causation framework, beginning with the precise date of breach and the care that should have followed. It then considers how radiology, pathology and oncology evidence can be used to reconstruct the claimant’s likely earlier clinical position.

It also explains why breast cancer cannot be treated as one uniform disease. Tumour subtype, grade, receptor status, size, nodal involvement and growth characteristics can materially affect the strength of the causation argument. A delay involving a slower-growing hormone receptor-positive cancer may require a different analysis from the same period of delay involving an aggressive HER2-positive or triple-negative tumour.

The eBook considers two key litigation scenarios: a missed screening abnormality that allowed a likely stage one tumour to progress, and a biopsy wrongly reported as benign where the patient was later diagnosed with HER2-positive breast cancer and liver metastases.

These examples demonstrate why treatment burden must be considered alongside survival. Even where a material reduction in life expectancy cannot be established, the delay may still have caused avoidable mastectomy, chemotherapy, radiotherapy, axillary surgery, prolonged systemic treatment or significant psychological harm.

The guide also addresses expert selection. A breast radiologist may be required to determine whether an abnormality was visible and reportable. A breast histopathologist may need to review the original biopsy slides. An oncologist will usually be required to assess stage progression, treatment burden, prognosis and whether the delay probably changed the outcome.

Written specifically for solicitors handling clinical negligence and personal injury claims, this guide offers a practical framework for preserving primary evidence, building the chronology and instructing each expert on questions that fall properly within their discipline.

Ultimately, breast cancer causation is not a single question. It is a sequence of questions about when the negligence occurred, what should have happened, what the cancer was probably like at that stage and what changed during the period of delay.

This guide was produced by INNEG and is based on key clinical and medico-legal insights shared during our webinar, Breast Cancer Delay Claims: Proving Causation, delivered by Dr Vasileios Angelis.