An oral scar-suppressing medicine. Its strongest human signal in cancer is protective rather than tumour-killing: restored oxygen passage after radiation lung injury, fewer sudden scarring flare-ups and deaths around lung surgery. The tumour-killing claim itself remains laboratory work; no life has been lengthened. Costs are dependable — nausea, rash, sun sensitivity, liver enzyme rises, appetite and weight loss. (Full Review)

Protocol

Standard antifibrotic dosing

801 mg three times daily

Licensed antifibrotic dose, 2403 mg per day, reached over a two-week titration. Oncology studies have used it at full strength or at reduced doses.

Reduced-dose radiation-injury regimen

200 → 300 → 400 mg three times daily

Week one, week two, then 400 mg three times daily through week 24, alongside tapering steroids.

Perioperative schedule

600 → 1200 mg daily

600 mg daily for two weeks, rising to 1200 mg daily; lung cancer surgery followed after at least two weeks at that dose.

Time to effect

Gas-transfer recovery

24 weeks

The randomised radiation-injury trial measured its endpoint at 24 weeks.

Before lung cancer surgery

At least 2 weeks

The perioperative protocol required at least two weeks at full dose before surgery.

Onset

Nothing within days

Lung-protective effects emerge slowly.

Benefits

Medium: Recovery of lung gas transfer after radiation-induced lung injury; prevention of fibrosis flares during cancer treatment

Low: Lower lung cancer incidence in progressive lung scarring; volume reduction in fibrous nerve-sheath tumours

Speculative: Sensitisation of tumours to chemotherapy and radiotherapy; restoration of immune cell entry into tumours; suppression of metastatic spread

Contraindications

Severe liver impairment (Child-Pugh Class C) or end-stage liver disease

Severe kidney impairment (creatinine clearance below 30 mL/min) or end-stage kidney disease requiring dialysis

Concurrent fluvoxamine therapy that cannot be substituted

Pregnancy and breastfeeding

Known hypersensitivity to pirfenidone or any tablet or capsule ingredient (including prior angioedema)

Key Interactions

Moderate CYP1A2 inhibitors (ciprofloxacin, enoxacin)

Combined multi-pathway inhibitors (fluvoxamine plus fluconazole, amiodarone, propafenone)

CYP1A2 inducers (rifampicin, omeprazole, carbamazepine)

Over-the-counter medications (omeprazole, esomeprazole, ibuprofen, naproxen)

Photosensitising drugs (doxycycline, levofloxacin, hydrochlorothiazide, amiodarone)

Caffeine and melatonin

Cruciferous (broccoli-family) and enzyme-inducing supplements (indole-3-carbinol, diindolylmethane, St. John's wort)

Supplements with additive antifibrotic action (N-acetylcysteine, curcumin, silymarin)

Other interventions (concurrent thoracic radiotherapy, checkpoint immunotherapy)

Risk & Side Effects

High: Gastrointestinal intolerance; photosensitivity and rash; elevated liver enzymes and drug-induced liver injury; weight loss and reduced appetite; fatigue, dizziness and headache

Medium: Serious adverse events during cancer treatment

Low: Severe hypersensitivity reactions; no demonstrated survival advantage in cancer cohorts

Speculative: Stromal depletion enabling tumour escape

Monitoring

Marker	Target	Why
Alanine aminotransferase	10–20 U/L (women), 10–25 U/L (men)	Earliest signal of drug-related liver stress
Aspartate aminotransferase	10–20 U/L (women), 10–25 U/L (men)	Confirms and cross-checks a rise in the first enzyme
Total bilirubin	0.3–1.0 mg/dL	Distinguishes harmless enzyme rises from genuine liver dysfunction
Estimated glomerular filtration rate	Above 90 mL/min/1.73 m²	The active metabolite is cleared by the kidneys
Body weight	No established target; within 5% of own baseline	Weight loss is the adverse effect most likely to interrupt cancer therapy
Serum albumin	4.0–5.0 g/dL	Marks the nutritional reserve available to absorb appetite suppression
25-hydroxyvitamin D	40–60 ng/mL	Enforced sun avoidance depletes it predictably
Gas-transfer capacity, percent predicted	Above 80% predicted, or stable against own baseline	The endpoint on which the strongest human benefit was demonstrated
Forced vital capacity, percent predicted	Above 80% predicted, or stable against own baseline	Detects progression of underlying lung scarring
Absolute neutrophil count	Above 1.5 × 10⁹/L	Guards the margin needed to continue chemotherapy safely

Cadence: Liver chemistry before starting, then monthly for the first six months and every three months thereafter; lung function at three-month intervals; imaging on the schedule the cancer protocol already sets; weight at every visit; vitamin D at baseline and every six months. Any dose change, or any newly added interacting drug, resets the monthly liver-testing clock.

Qualitative Assessment

Appetite and the size of meals actually finished, rather than meals offered
Nausea severity in the hour after each dose, which reveals whether food timing is working
Skin reaction to ordinary daylight exposure, including through window glass
Breathlessness on a fixed, repeatable task such as one flight of stairs
Energy and daytime alertness, distinguishing drug fatigue from cancer-treatment fatigue by its timing relative to doses
Sleep onset and morning drowsiness, especially where caffeine or melatonin intake has not been adjusted

Pirfenidone to Treat Cancer

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment