Two-Modality Mammography May Confer an Advantage Over Either Full-Field Digital Mammography or Screen-Film Mammography

Rationale and Objectives

We sought to compare the cancer detection rate and receiver operating characteristic (ROC) area under the curve of full-field digital mammography, screen-film mammography, and a combined technique that allowed diagnosis if a finding was suspicious on film mammography, on digital mammography, or both.

Materials and Methods

We used the data originally analyzed by Lewin and associates in 2002. In that trial, 6,736 paired full-field and digital mammograms were performed in 4,489 women. We used parametric and nonparametric tests to compare the area under the curve for ROC scores of film-screen only, digital mammography only, and the combined test. We used McNemar’s test for paired proportions to compare the cancer detection rates.

Results

With the parametric test, neither the difference in the area under the curve between the film and combined nor the difference between the digital and combined ROC curves was significant at the Bonferroni-corrected 0.025 α level (film versus combined difference = 0.0563, P = .0712; digital versus combined difference = 0.0894, P = .0455). The nonparametric test showed that there was a significant difference between both film and combined (difference = 0.073, P = .008) and digital versus combined ROC curves (difference = 0.1164, P = .0008). The continuity-corrected McNemar’s test showed a significant increase in the proportion of cancers detected by the combined modality over film (χ 2 = 7.111, df = 1, P = .0077), and over digital (χ 2 = 12.071, df = 1, P = .0005).

Conclusion

Using two mammograms, one film and one digital, significantly increases the detection of breast cancer.

Three recent clinical trials with paired designs have compared full-field digital and screen-film mammography ( ). Each woman was imaged with both digital and film machines. The purpose of these trials was to compare the diagnostic accuracy of the digital and film approaches. Interestingly, in each study, more cancers were detected than would have been detected by either modality alone ( Table 1 ). This suggests that full-field digital mammography and screen film mammography could be used in tandem to improve breast cancer detection.

Table 1

Proportions of Cancer Detected by Each Modality in Three Clinical Trials

Trial Screen Film Mammography Full-Field Digital Mammography Combined Modalities Lewin et al. ( ) 32/49 = 65.3% 27/49 = 55.1% 41/49 = 83.7% Skaane et al. ( ) ⁎ 28/31 = 90.3% 23/31 = 74.2% 31/31 = 100% Pisano et al. ( ) 174/335 = 51.9% 185/335 = 55.2% 237/335 = 70.7%

⁎ No interval cancers were reported in this study.

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Materials and methods

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Results

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Table 2

Parametric ROC Analysis Results

Statistics Film Versus Combined Digital Versus Combined Film Versus Digital First modality AUC 0.831 0.7956 0.8283 Standard error 0.0406 0.0267 0.0423 Second modality AUC 0.8873 0.885 0.7865 Standard error 0.0259 0.0509 0.0538 AUC difference 0.0563 0.0894 0.0418 Standard error difference 0.03122 0.04467 0.06357Z -score 1.8045 1.9996 0.6587P value .0712 .0455 .5101

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Table 3

Nonparametric ROC Analysis Results

Statistics Film Versus Combined Digital Versus Combined Film Versus Digital First modality AUC 0.7811 0.7377 0.7811 Standard error 0.037 0.0381 0.037 Second modality AUC 0.8541 0.8541 0.7377 Standard error 0.0315 0.0315 0.0381 AUC difference 0.073 0.1164 0.0434 Standard error difference 0.0275 0.0347 0.0501 χ 2 ( df = 1) 7.0397 11.281 0.7507P value .008 .0008 .3863

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Discussion

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Acknowledgment

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References

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Two-Modality Mammography May Confer an Advantage Over Either Full-Field Digital Mammography or Screen-Film Mammography

Rationale and Objectives

Materials and Methods

Results

Conclusion

Materials and methods

Results

Discussion

Acknowledgment

References

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