How is cancer detection rate calculated?

Cancer detection rate = (Number of breast cancers detected) ÷ (Total number of mammograms performed) × 1,000. For example, if a facility performs 5,000 screening mammograms in a year and detects 25 breast cancers, the CDR is 5.0 per 1,000. For the calculation to be valid, 'cancers detected' must include only cancers confirmed by pathology that were identified through the mammography program — not cancers found incidentally or through unrelated procedures. Interval cancers (cancers that present clinically between screening examinations) are tracked separately.

What is the ACR benchmark for cancer detection rate?

The American College of Radiology (ACR), citing data from the Breast Cancer Surveillance Consortium (BCSC), identifies a target cancer detection rate of 2–7 cancers per 1,000 screening mammograms. The range reflects real variation in CDR based on population characteristics: a facility serving a higher-risk population (older women, family history, dense breasts) would be expected to have a CDR closer to or above the upper end of the range. A facility serving a younger, lower-prevalence population may have a CDR near the lower end. Context matters — CDR should be interpreted alongside recall rate and PPV, not in isolation.

What causes a low cancer detection rate?

A CDR below 2 per 1,000 may indicate several things: under-detection by interpreting radiologists (findings are present but not being identified or acted on); a patient population with genuinely low cancer prevalence (young age, low-risk factors); incomplete pathology correlation in the audit (cancers are being found but not linked back to the originating mammogram in the audit data); or a methodology problem in how 'detected' cancers are counted. Low CDR is considered a more serious performance concern than high CDR, because it may mean the program is missing cancers that should have been found.

What causes a high cancer detection rate?

A CDR above 7 per 1,000 may reflect a high-risk patient population, an aggressive screening program with high follow-up and biopsy completion rates, or a facility with excellent pathology correlation that captures virtually all biopsy-confirmed cancers back to their originating mammogram. In some cases, a CDR above the upper benchmark can result from selective screening populations — for example, a facility that screens primarily high-risk patients under supplemental MRI protocols alongside mammography. CDR should be contextualized against the facility's patient demographics before drawing conclusions.

Is cancer detection rate tracked per physician?

Yes — MQSA requires that medical audit metrics including CDR be tracked and analyzed at the individual interpreting physician level, not only at the facility level. Per-physician CDR allows the facility to identify whether differences in cancer detection exist between interpreting physicians that might reflect systematic differences in threshold, technique, or practice patterns. A physician with a significantly lower CDR than peers at the same facility, with a comparable patient population, is a finding that warrants investigation. Per-physician tracking is what gives the medical outcome audit its value as a quality tool.

How does cancer detection rate relate to recall rate?

CDR and recall rate (AIR) should always be interpreted together. The key ratio is: how many recalls does it take to find one cancer? A facility with a recall rate of 8% and a CDR of 5 per 1,000 is more efficient than a facility with a 12% recall rate and a CDR of 3 per 1,000. The latter is recalling 50% more patients but detecting 40% fewer cancers — a pattern suggesting over-calling without proportional detection benefit. Together, CDR and recall rate describe the efficiency of the screening program's cancer detection process.

How does CDR connect to positive predictive values?

Cancer detection rate and PPV values measure complementary aspects of program performance. CDR measures the absolute yield of the program — how many cancers per 1,000 patients screened. PPV1 measures the cancer yield per recall (BI-RADS® 0 event). PPV2 measures the cancer yield per biopsy recommendation. CDR can be high even if PPV1 is low (if the facility is recalling many patients and finding cancers in proportion). Conversely, PPV2 can be high even if CDR is moderate (if the facility does few biopsies but biopsies very efficiently). A complete audit uses all of these metrics together.

What is the difference between CDR and sensitivity?

Cancer detection rate and sensitivity are related but different measures. CDR is an absolute count — cancers detected per 1,000 mammograms — and depends on the prevalence of cancer in the screened population. Sensitivity is a proportion — the percentage of cancers that were present and were found by the program. A program with high sensitivity finds most of the cancers that were there; a program with low sensitivity misses a meaningful proportion. Sensitivity requires knowledge of interval cancers (cancers that presented clinically between screening rounds) to calculate, making it operationally more complex to track than CDR. The ACR benchmark for sensitivity is 75–90%.

What happens when CDR falls outside the benchmark range?

When a facility's or physician's CDR falls outside the ACR benchmark range, MQSA requires the facility to take corrective action. For CDR below the lower benchmark (below 2 per 1,000), the response is typically more urgent — the facility must investigate whether under-detection is occurring, review audit data completeness (particularly pathology correlation), and evaluate interpreting physician performance. The corrective action process and documentation must be maintained and available for FDA inspection review. MQSA inspectors review medical outcome audit data including CDR as part of standard annual inspection protocol.

How does interval cancer rate relate to CDR?

Interval cancers — breast cancers that are diagnosed after a negative or benign mammogram, before the next scheduled screening — are the complement of detected cancers. A high interval cancer rate suggests that cancers present at the time of screening were missed. Tracking interval cancers requires follow-back on patients who had normal or benign mammograms and subsequently developed breast cancer, which is operationally demanding but provides important context for interpreting CDR. Facilities with complete interval cancer data can calculate true sensitivity. Facilities without it rely on CDR and PPV as proxies for program effectiveness.

How does Mammologix support cancer detection rate tracking?

Mammologix tracks CDR as part of full MQSA medical outcome audit support. This includes capturing all positive assessments from screening mammography, monitoring follow-up completion, documenting biopsy outcomes and pathology results, calculating CDR at the physician and facility level, benchmarking against ACR/BCSC targets, and flagging performance outside expected ranges. Because CDR depends on complete pathology correlation, Mammologix audit support includes a structured workflow for retrieving and recording pathology results for every biopsy recommendation generated by the program — the foundation on which accurate CDR depends.

Definitional Guide

What Is Cancer Detection Rate in Mammography?

Q: What is cancer detection rate in mammography?

Cancer detection rate (CDR) in mammography is the number of breast cancers detected per 1,000 mammograms performed. It is the most direct measure of whether a breast imaging program is succeeding at its primary purpose: identifying breast cancer in the people being screened. CDR is one of the core performance metrics required by MQSA's medical outcome audit and is tracked both at the individual interpreting physician level and at the aggregate facility level.

The CDR — cancers found per 1,000 mammograms — explained for the breast imaging professionals who calculate it, benchmark it, and defend it at MQSA inspections.

MQSA MetricACR Benchmark: 2–7 per 1,000Per-Physician TrackingAnnual Review Required

Cancer Detection Rate in Plain Language

Cancer detection rate (CDR) is the number of breast cancers confirmed through your mammography program per 1,000 mammograms performed. It is the most direct answer to the most fundamental question a breast imaging program can ask: is this program finding cancer at the rate it should?

Every other quality metric in mammography — recall rate, PPV, sensitivity, specificity — is ultimately in service of this one. Recall rate tells you how often you’re recommending additional workup. PPV tells you how efficiently those recommendations are converting to confirmed diagnoses. CDR tells you the bottom line: how many cancers per 1,000 patients is the program actually catching.

Under MQSA, CDR must be tracked per interpreting physician and per facility as part of the required annual medical outcome audit. The audit compares each physician’s CDR against the facility average and against published ACR benchmarks — and requires documented corrective action when the rate falls outside expected ranges.

2–7

ACR Target (per 1,000)

×1,000

Calculation Multiplier

Annual

Audit Review

Per MD

Tracking Level

CDR in Context — The Full Metric Picture

CDR is most meaningful when read alongside the other core audit metrics. Each metric answers a different question about program performance.

Cancer Detection Rate

Answers: How many cancers per 1,000 mammograms?

Measures: The absolute yield of the program.

ACR target: 2–7 per 1,000

Recall Rate / AIR

Answers: What percentage of screened patients are recalled?

Measures: The cost (in patient returns) of the detection program.

ACR target: 5–12%

PPV1

Answers: What percentage of recalls result in cancer?

Measures: The cancer yield per recall event.

ACR target: 3–8%

PPV2

Answers: What percentage of biopsy recommendations result in cancer?

Measures: The cancer yield per biopsy recommendation.

ACR target: 20–40%

Sensitivity

Answers: What proportion of cancers present were found?

Measures: How complete the detection is relative to cancers present.

ACR target: 75–90%

The Most Common CDR Problem

Incomplete Pathology Correlation Undermines CDR

CDR can only be as accurate as the pathology correlation behind it. A cancer cannot be counted as “detected” in the audit unless the biopsy result is retrieved and linked back to the originating mammographic assessment. When pathology results go missing — because the biopsy was performed at another facility, results were sent to a different provider, or there is no systematic retrieval process — the CDR is artificially deflated.

Biopsies performed at an outside facility often return results to the referring physician, not to the mammography program — creating a data gap
Without a defined workflow for retrieving pathology on every biopsy recommendation, CDR will undercount detected cancers
An artificially low CDR can trigger MQSA corrective action for a problem that is administrative, not clinical
Complete pathology correlation is the most operationally demanding — and most important — component of a reliable audit program

If your CDR seems lower than expected, check pathology correlation completeness before assuming a detection problem.

Many facilities with apparently low CDRs are actually detecting cancers at a normal rate — they just cannot account for all of them in their audit data because pathology retrieval is incomplete. This is one of the most common audit findings Mammologix encounters when taking on a new client.

Cancer Detection Rate — Frequently Asked Questions

Detailed answers to the questions breast imaging professionals ask most often about CDR calculation, benchmarks, and MQSA audit requirements.

BI-RADS® is a registered trademark of the American College of Radiology.

How Mammologix Helps

CDR Tracking and Audit Support

Mammologix tracks cancer detection rate as part of full MQSA medical outcome audit support — including the pathology correlation workflows that CDR depends on. We retrieve, document, and link pathology results back to originating assessments so your CDR reflects actual performance, not a data gap.

Medical Outcome Audit GuideComplete guide to the MQSA-required audit — CDR, recall rate, PPV, benchmarks, and compliance.Learn more →What Is Recall Rate?How recall rate and CDR work together to tell the complete performance story.Learn more →MammoTrackPatient tracking, pathology correlation workflows, and audit-ready outcome documentation.Learn more →MammoComplyMQSA compliance support, inspection readiness, and annual audit preparation.Learn more →

Talk to Mammologix About Audit Support Explore MammoTrack

About the Author

Richard “Rick” Lippert Jr.

ARRT · President & Founder, Mammologix · Breast Imaging Operations since 1995

A registered radiologic technologist and founder of Mammologix, Rick Lippert has spent more than 30 years in breast imaging operations — from clinical practice and hospital radiology administration to building specialized service platforms for imaging centers nationwide. His work spans mammography tracking, lay communication, FDA/MQSA-related support, medical outcome audit, and the operational systems that help facilities stay compliant and keep patients from falling through the cracks.

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