This page focuses on one specific situation: a breast cancer that was missed or misread on a mammogram. It sits below our wider guide to breast cancer misdiagnosis claims in Ireland, which covers the whole diagnostic pathway and claim. It also sits below our guide to misread scans, biopsies and histopathology, which covers reading errors across every type of imaging. Here we stay with the mammogram itself, because the evidence that wins or loses these cases is specific to it.

How breast cancer is missed on a mammogram in Ireland

A mammogram can miss a cancer in more than one way, and the difference matters for any claim. The Health Service Executive sets out three recognised types of interval cancer, meaning a cancer found in the gap between routine screens.¹ Understanding which type applies is the starting point, because only some of them point toward negligence.

According to the HSE National Screening Service, the three types are:

• Newly developed (common). The cancer was not present at the last screen and grew afterwards. This is an ordinary feature of any screening programme and usually points away from negligence.
• Visible but subtle (less common). Signs were present on the earlier film but were faint and judged to be normal at the time.
• Visible but missed (rare). Signs were present and should have prompted recall, but were not acted on.²

The HSE is explicit that a normal mammogram does not rule out breast cancer entirely, and that cancer can appear at any time between appointments.² That honesty cuts both ways. It explains why a later diagnosis is not, by itself, proof of a failed read, and it explains why the rare third category is where most screening claims live.

Mammography also has known limits. Dense breast tissue can hide a tumour, and some cancers sit in positions that are hard to see on a standard film. That is part of why a normal mammogram is not a clearance, and why a lump that can be felt is treated separately from the image.

It helps to separate the two pathways, because the law treats them differently. BreastCheck is for women aged 50 to 69 with no symptoms, screened every two years. The symptomatic pathway is the opposite case, where a woman has noticed a lump or other change and is referred by her GP. Under the National Cancer Control Programme referral guidance, a clinically suspicious lump should be referred for triple assessment, which is clinical examination, imaging and a biopsy where indicated.³

A normal mammogram does not remove that duty. Where a clear scan reassured away a lump you could feel, the failure may be a failure to refer for urgent investigation, not a misread image. We look at red-flag symptoms that were not investigated separately.

When a missed mammogram is negligence, and when it is not

The honest answer is the one most worth giving: not every cancer found after a clear mammogram is the result of negligence. Irish law draws a hard line between a true interval cancer and a negligently missed one, and that line decides the case.

The point was settled in Freeney v HSE, a 2020 High Court action concerning a BreastCheck screening. The plaintiff's June 2015 mammogram was read by two radiologists, neither of whom recommended recall, and she was diagnosed later that year. Ms Justice Niamh Hyland found that the cancer was a true interval cancer. The earlier film showed only normal or benign features, so reporting it as normal was not negligent.⁴

The judgment also made an important clarification. The "no doubt" standard from the CervicalCheck case of Morrissey v HSE is not an automatic rule for every screening case. The radiologists' reading is judged against the ordinary Dunne standard of care.⁵

What turns a missed read into a breach is the contemporaneous image. Radiologists grade mammograms using BI-RADS assessment categories, which run from 1 (negative) and 2 (benign) through 4 (suspicious) to 5 (highly suggestive of cancer). A claim is built when an independent consultant radiologist reviews the original film. The expert shows that suspicious features, such as clustered micro-calcifications or architectural distortion, were visible at the time. The film should have been scored 4 or 5 rather than 1 or 2.⁶

The screening read itself has a standard built into it. In the Irish National Breast Screening Programme, every screening mammogram is independently read by two radiologists, and where their recall opinions differ the case goes to a consensus review.¹² That double-reading and consensus process is the benchmark a screening claim is measured against. A claim is stronger where the records show the process was not properly followed, and weaker where it was followed and the features were not visible at all.

The original score against the corrected score is the documentary foundation of the breach, which is why obtaining the original report is one of the first practical steps. This is the same reading-error analysis we apply across radiology misdiagnosis, applied here to the breast.

That standard sits on long-settled ground. The test for clinical negligence in Ireland comes from Dunne v National Maternity Hospital. It asks whether the clinician fell below the standard of a competent professional of equal specialist status.⁸ There is an added Irish safeguard: a common practice can still be negligent if it has inherent defects that ought to be obvious on careful consideration.

The BreastCheck mammogram review and what it means for a claim

There is a step many people are never told about. If you are diagnosed with breast cancer within two years of a BreastCheck mammogram, you can ask the National Screening Service to review your last screening film.¹ The review is carried out by two consultant radiologists who were not involved in your original screening, and who assess whether that screening was satisfactory. You are contacted with the outcome and sent a copy of the review report.¹

That report can matter a great deal. It is an independent, contemporaneous assessment of the very thing a claim turns on, namely whether the earlier film was read to standard. It can support a claim, and it can equally confirm that a screen was satisfactory and the cancer was a true interval one.

Either way it is evidence, and it interacts with two other things. It can fix your date of knowledge, because the point at which you learn an earlier scan was inadequate is often the point the legal clock starts. And it sits alongside the duties in the Patient Safety (Notifiable Incidents and Open Disclosure) Act 2023, which commenced on 26 September 2024.¹⁰ As well as mandatory open disclosure of certain serious incidents, the Act gives patients a right to request a review of their cancer screening. The screening service must share the result at a meeting and in a written summary within five days.

A short example shows why this matters for the deadline. A screen is reported as clear, a cancer is diagnosed two years later, and a review report then confirms the earlier film was inadequate. The clock for a claim does not run from the original screen. It runs from the point you knew, or should have known, that the earlier screening was at fault, which the review report often supplies.

How to request your mammogram images and an independent review

You have a right to the images themselves, and you do not need a solicitor to ask for them. There are two separate routes, and they do different jobs.

The first is a records request. You can ask for your previous BreastCheck mammograms at any time, and the request is handled under your right of access in Article 15 of the GDPR.¹³ The second is the screening review described above, where two radiologists who were not part of the original read assess whether the screening was satisfactory. The HSE sets out that you can request your previous BreastCheck mammograms for an independent review by emailing the programme directly.¹³

For symptomatic imaging taken at a hospital rather than through BreastCheck, the same right of access applies through that hospital's records process. In both cases the original images, not a later summary, are what an independent consultant radiologist needs in order to say whether the film was read to standard.

How to tell if your case is worth investigating

No online guide can tell you whether you have a claim, because it turns on the original films and the medical facts. The questions below are the ones we work through at the start, and they track the difference between a true interval cancer and a negligently missed one.

Gathering the right records early makes that assessment possible. The documents that usually matter are the original mammogram images, the radiologist's report and its BI-RADS score, any BreastCheck review report, and your GP referral and clinic records. We request these through the data-access process so an independent expert can review the original images rather than a later summary.

In practice the sequence usually runs in this order.

1. Request your records and images. Ask BreastCheck or the treating hospital for the original mammograms under your GDPR right of access.
2. Request a screening review. Where the mammogram was a BreastCheck screen, ask for the two-radiologist review and keep the review report.
3. Get an independent radiology opinion. An independent consultant radiologist re-reads the original film against the BI-RADS standard.
4. Take legal advice within the deadline. Because the clock can already be running, speak to a solicitor before the two-year limit, not after the evidence is gathered.

Why some missed-mammogram claims fail: the causation hurdle

Proving a film was misread is only half of a claim. You must also prove causation, meaning that the delay changed your treatment or your outcome. This is where sincere, well-meant cases come undone, and it is the part competitors rarely explain.

The difficulty has a name in practice, sometimes called the doubling-time or "Goldilocks" problem, and it defeated the plaintiff in Crumlish v HSE. The plaintiff alleged a five-month delay in diagnosing her breast cancer and sought substantial damages. Her case rested on an estimate of how fast the tumour had doubled in size, used to argue the cancer must have been detectable at the earlier date. The High Court rejected that evidence. In 2024 the Court of Appeal upheld the dismissal, holding that once the doubling-time evidence fell away the claim failed at the first causation hurdle.⁷

The trap works in both directions. If a tumour was growing slowly, the defence argues the delay made little difference to the outcome. If it was growing quickly, the defence argues it was a true interval cancer that was not detectable at the earlier screen at all. The Court of Appeal also warned against expert evidence that fits the science to the client's account rather than the other way round.⁷

The practical lesson is that the strongest cases rest on what the original films show, not on a mathematical model of how a tumour grew. We explain how causation is proven in delayed-diagnosis claims in more detail separately.

What your claim may include

Where breach and causation are both made out, a personal injury claim for a missed breast cancer is valued in two parts. General damages compensate the pain, suffering and loss of amenity caused by the delay, and are assessed under the Personal Injuries Guidelines.¹¹ Special damages cover financial losses that flow from the delay, such as the cost of more extensive treatment, lost earnings, and care.

The driver of value is usually the difference the delay made to the stage at which the cancer was treated, and the heavier treatment that followed. That stage difference, and the lost opportunity of earlier and less invasive treatment, is a recognised compensable injury in Irish law. It is why we treat loss of chance as central rather than incidental. Every case is assessed on its own medical facts, and past settlements are not a guide to any future outcome.

Time limits and the date of knowledge

Act early, because the deadline is strict. You have two years less one day to begin proceedings, and the clock runs from your date of knowledge rather than the date of the missed scan.⁹ In screening cases that date is frequently much later than the mammogram itself. You may only learn the earlier film was inadequate on a recurrence, on a second opinion, or when a BreastCheck review report or an open-disclosure meeting tells you so.

One procedural point catches people out. Clinical negligence claims are exempt from the Injuries Resolution Board (IRB) under section 3(d) of the PIAB Act 2003.⁹ A missed breast cancer claim does not go through the IRB and instead proceeds directly to the High Court. Submitting it to the Board does not pause the two-year clock, so the date-of-knowledge analysis on our date of knowledge page is worth reading early.

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Common questions