CT scans could cause 5% of cancers, study finds; experts note uncertainty

Risk–benefit and overuse of CT scans

• Many argue that by the time a CT is ordered, the suspected condition is usually riskier than the incremental cancer risk.
• Others counter that CTs are often ordered “just in case,” especially in chronic or ambiguous cases, suggesting overuse and poor justification.
• Several anecdotes show both sides: unnecessary scans later rendered moot by simple treatments vs. delayed CT leading to late cancer diagnosis.
• Commenters want EMRs to track cumulative radiation and more explicit risk discussions before ordering scans.

CT vs MRI vs X‑ray

• Recurrent theme: “Why not MRI instead?”
• Responses: CT is faster, higher resolution in many contexts, better for certain pathologies (e.g., lungs, acute stroke, some post‑cancer surveillance), and usable in patients with metal implants.
• MRI is slower, more resource‑intensive, needs helium, can’t be used with some implants, and often needs contrast (whose long‑term risks are debated but currently lack compelling evidence of cancer causation).
• Some say single X‑rays are preferable to CT for bones; others note many abdominal/chest questions genuinely require CT detail.

Radiation dose, models, and uncertainty

• Multiple comments emphasize that the study is a modeling exercise, extrapolating from radiation dose to expected cancers, not directly counting cancers after CT.
• Critiques: highly confounded population (people needing CT are already sicker), unclear handling of prior disease, and no direct answer to “does this scan improve lifespan/quality of life?”
• Debate over Linear No‑Threshold (LNT) vs possible thresholds or even hormetic effects at low doses; some say evidence for low‑dose harm is weak, others insist ionizing radiation is necessarily carcinogenic in proportion to dose.
• Strong skepticism about the “5% of cancers” estimate; some say if that were true, population‑level signals (e.g., by country CT usage) should be obvious.

Preventive screening and incidental findings

• Discussion on whether broad preventive imaging is wise: risk of false positives, invasive follow‑ups, and overtreatment for very rare diseases.
• Contrasting anecdotes: “full‑body” scans catching early, manageable issues vs. counterpoints that most such findings track age‑related changes and don’t require imaging to justify lifestyle advice.

Emotional impact and communication

• Several commenters with multiple CTs express anxiety after reading such studies.
• Others stress putting risk in context (e.g., flights, occupational exposure, improved low‑dose scanners) and argue media coverage of statistical risks is often misleading or sensational.