Will a Breast Tumor Show Up on an X-ray (Mammogram)?
Yes, breast tumors can show up on mammography (breast X-ray), but mammography detects only 86-91% of breast cancers, meaning it will miss approximately 9-14% of tumors. 1
Detection Rates and Limitations
- Mammography's sensitivity for detecting breast cancer ranges from 86% to 91% when evaluating palpable breast abnormalities. 1
- The greatest limitation of mammography is breast tissue density—very dense tissue makes detection of breast cancer difficult, and tumors can be masked by overlapping normal tissue. 1, 2
- Interval cancers (tumors that appear between screening mammograms) tend to be more aggressive, occur more in younger women, and are of larger tumor size than screen-detected cancers. 3
What Mammography Can Detect
- Mammography can identify calcifications, masses, architectural distortions, and asymmetries that may represent breast cancer. 1
- Early stage tumors, including intraductal carcinoma and stage I infiltrating ductal carcinoma, can be detected on mammograms, with calcifications being the most common finding. 4
- Tumors with tubular histology or high percentage of in situ components (≥50%) are more likely to be detected by screening mammography. 3
Tumors More Likely to Be Missed
- Tumors with lobular histology (odds ratio 1.9) or mucinous histology (odds ratio 5.5) are more likely to be missed by mammography and surface between screening examinations. 3
- Rapidly proliferating, high-grade tumors with high mitotic count (odds ratio 2.9) or high Ki-67 expression (odds ratio 2.3) are more likely to be interval-detected rather than screen-detected. 3
- Tumors with high histologic grade (odds ratio 2.1), high nuclear grade (odds ratio 2.0), or negative estrogen receptor status (odds ratio 1.8) are associated with interval detection. 3
Critical Clinical Approach
The addition of ultrasound to mammography detects 93-100% of cancers that are occult on mammography, and when both mammography and ultrasound are negative or benign, the negative predictive value is very high at more than 97%. 1
- For women ≥40 years with a palpable mass, diagnostic mammography should be performed first, followed by targeted ultrasound regardless of mammography results. 5
- For women <30 years, proceed directly to targeted breast ultrasound as the initial study, as breast cancer incidence is <1% in this age group and most benign lesions are not visualized on mammography. 5, 6
Important Caveats
- A negative mammogram should never deter biopsy of a clinically suspicious mass—negative imaging evaluation should never overrule a strongly suspicious finding on physical examination. 1, 2
- Any highly suspicious breast mass detected by imaging or palpation should undergo biopsy unless there are exceptional clinical circumstances. 1
- Digital breast tomosynthesis (DBT) can address some limitations of standard mammography by decreasing the lesion-masking effect of overlapping tissue, with specificity as high as 98% when re-staging suspicious findings. 7