Cheap blood test detects pancreatic cancer before it spreads

Original Article ↗ Hacker News Discussion ↗

Who Should Be Tested and How Often

  • Many argue this kind of non‑invasive test is only useful if given to asymptomatic people, because pancreatic cancer is usually detected too late to treat.
  • Debate over whether it should be “everyone, frequently” vs. age‑ or risk‑based cohorts (e.g., 30+, 40+, family history).
  • Some propose infrequent interval screening (every 5–10 years) for low‑risk adults; others stress cancer can form at any time, implying more frequent testing.

False Positives, Overdiagnosis, and Harm

  • Several commenters push back hard on the idea that a false positive is “just an extra scan”:
    • Follow‑up tests (CT, MRI, biopsy, colonoscopy, surgery) carry non‑trivial risks, including death and long‑term harm.
    • Overdiagnosis can lead to treating cancers a person would have died with, not from, worsening overall outcomes.
  • Others counter that for a near‑universally lethal cancer with no good screening, more false positives may be acceptable, but concede the “right balance” is unclear.

Statistics and Base Rate Issues

  • With a 98% specificity and relatively rare disease (≈1 in 10,000 per year), commenters note that population‑wide annual screening could generate ~200 false positives per true positive, even before considering imperfect sensitivity.
  • Bayesian base‑rate fallacy is repeatedly invoked: even apparently “good” tests can have low positive predictive value when prevalence is low.
  • Some suggest repeat testing to reduce false positives, but others note biological, not random, noise may dominate, limiting gains.

Comparisons to Existing Screening

  • Colon, breast, prostate, cervical, and skin cancer screening practices are used as analogies, with ongoing debates over colonoscopy vs stool tests, PSA testing, and when to stop screening in old age.
  • Prostate cancer is highlighted as a cautionary tale: more detection increased treatment and 5‑year survival stats without clearly reducing mortality.

Proactive Bloodwork, Cost, and Access

  • Strong sentiment that current systems are too reactive; people want broad periodic blood panels and easier self‑ordering of tests.
  • Barriers cited: insurance coverage, physician gatekeeping (both for safety and liability), test costs, and capacity constraints.
  • Some mention existing multi‑cancer blood tests (e.g., liquid biopsies) and private services, but note high price, modest sensitivity, and lack of outcome data.

Emotional Context and Funding

  • Numerous personal stories of rapid deaths from pancreatic cancer drive enthusiasm for any early‑detection tool, even if imperfect.
  • Brief debate on US research funding changes (NIH indirects, DARPA‑style smaller grants) and their potential impact on groups developing such tests.