Table 2. Expected outcome of screening for breast cancer with breath test.

		CANCER STATUS
		Positive	Negative		Pre-test value (%)	Post-test value (%)	Enrichment factor
TEST	positive	TP = 3,231	FP = 298,815	PPV	0.395	1.070	2.708
RESULT	negative	FN = 719	TN = 697,235	NPV	99.605	99.897	1.003
	Total	3,950	996,050

The table summarizes the expected outcome of screening one million women in the USA with a breath test, assuming test sensitivity = 81.8% and specificity = 70.0% (Figure 1, middle panel), and prevalence of breast cancer is 3.95 cancers per 1000 (based on mean cancer detection rate of screening mammography) [44]. TP = true positives, FP = false positives, FN = false negatives, and TN = true negatives. PPV and NPV are positive and negative predictive value respectively, where PPV = TP/(TP+FP), NPV = TN/(TN+FN), and enrichment factor = post-test value/pre-test value.