$5 device tests for breast cancer in under 5 seconds: study
A prototype $5 saliva-based sensor for breast cancer biomarkers has generated interest because it promises ultra-cheap, rapid screening using disposable test strips and a reusable circuit board. Commenters note that the underlying physics and immunoassay concepts are plausible, but criticize the tiny sample size (21 patients), weak clinical validation, and reliance on biomarkers not currently used for screening, warning that current claims of “accuracy” are premature. Many see it as an early proof-of-concept for a detection technology that might one day complement, but not replace, established imaging and biopsy methods if larger, well-designed trials confirm real-world sensitivity and specificity.
Study design, statistics, and reliability
- Experiment is very small: N=21 (4 healthy, 3 in-situ cancers, 14 invasive; only 1 HER2+ case).
- Several commenters argue this is too underpowered to assess accuracy, false positive/negative rates, or clinical utility.
- Others note that small-N studies can still show meaningful effects if the effect size is large and sampling is unbiased, but emphasize that you must actually compute the stats rather than dismiss on N alone.
- Figures show substantial overlap between groups; same reading could correspond to healthy or cancer, suggesting significant false positives/negatives.
- Concerns raised about:
- Very few non-cancer controls.
- Unclear replication and lack of error bars in key figures.
- Misinterpretation of p-values (e.g., p=0.002) as false-positive probabilities.
- No reported sensitivity, specificity, predictive values, or Bayes factors.
Biomarkers and clinical relevance
- Device targets HER2 and CA15-3 in saliva using antibody-coated strips.
- Multiple comments stress these are not standard screening markers for breast cancer:
- HER2 is routinely tested on tumor tissue to guide therapy, not for population screening.
- CA15-3 is often used relative to a personal baseline for monitoring, not diagnosis.
- Some breast cancers (e.g., HER2-negative, TNBC) would not be detected.
- One commenter argues the paper overstates novelty and understates that fast clinical immunoassays for these proteins already exist.
- Consensus: current work is better seen as proof-of-concept for a detection method, not a validated screening test.
Hardware, cost, and prototype quality
- PCB photo (many DIP ICs, BNC connectors) draws skepticism from some who see it as amateurish.
- Others point out this is typical lab-prototype style from physics/vacuum groups; the real innovation is in the functionalized strips, not the electronics.
- Claimed economics: reusable board around $5, strips a few cents. Several note real-world pricing and margins would likely be much higher.
Screening role, harms, and policy
- General agreement it would at most be a cheap, non-invasive screener; positive results would still require imaging and biopsy.
- Some highlight that more screening is not automatically better due to overdiagnosis, false positives, and harmful follow-up procedures.
- Cheap, low-risk tests with high precision (even if low recall) could still be useful as a first-pass filter, especially in low-resource settings—if future studies show adequate performance.
Hype, Theranos comparisons, and publication venue
- Media headline (“accurate $5 test in 5 seconds”) is widely viewed as premature or misleading relative to the small, exploratory dataset.
- Comparisons to Theranos appear; rebuttals emphasize this group is publishing real, limited data and clearly stating sample size, not secretly faking results.
- Publication in Journal of Vacuum Science & Technology B is seen by some as appropriate for a thin-film/FET sensor; others doubt the journal’s expertise in cancer diagnostics and clinical statistics.