Reducing Respiratory Symptoms of Pulmonary Irradiation in Interstitial Lung Disease

Inclusion criteria

• Lung cancer or 1-2 oligometastatic pulmonary lesions planned for radical intent radiotherapy \[minimal Biologically Effective Does (BED) of 48 Gy10 (Gray) or biological equivalent\].
• Pathologically (histologically or cytologically) proven diagnosis of cancer is not required, but strongly recommended.
• If the risk of biopsy is unacceptable, pathologic confirmation is not required providing there is growth over time on Computed Tomography (CT) imaging and/or Fluorodeoxyglucose (FDG) avidity that is strongly suggestive of malignancy.
• Fibrotic Interstitial Lung Disease (ILD) of any subtype, as diagnosed by a respirologist and confirmed by central review
• Eastern Cooperative Oncology Group (ECOG) performance status 0-3
• Age ≥ 18
• Life expectancy \> 6 months
• Patients are allowed to receive anti-fibrotic agents used in the treatment of Idiopathic Pulmonary Fibrosis (IPF) or non-IPF fibrotic ILD (e.g. nintedanib, pirfenidone) and/or corticosteroids, if those are part of their current ILD treatment regimen. Other immunosuppressive drugs such as mycophenolate, azathioprine, cyclophosphamide, and rituximab must be stopped for 2 weeks prior and 2 weeks after Radiation Therapy (RT).
• Concurrent standard chemotherapy is allowed where indicated. All other systemic therapies, including biologic targeted agents or immunotherapy, or any drugs with known radiosensitive effects, must be stopped for 2 weeks prior and 2 weeks after treatment.

Exclusion criteria

• Prior lung radiotherapy
• Current use of oral or intravenous corticosteroids
• Plans for the patient to receive other local therapy to the target lesion(s) while on this study, except at disease progression
• Any medical condition that could, in the opinion of the investigator, preclude radiotherapy or prevent follow-up after radiotherapy
• Pregnancy
• If not pregnant, use of effective contraception methods for women of childbearing age is required which can include:
• hormonal methods (e.g. oral, injected, implanted),
• placement of an intrauterine device,
• barrier methods (i.e. condoms),
• sterilization of the partner (e.g. previous vasectomy)
• abstinence
• Women who become pregnant should stop taking NAC and/or dexamethasone and inform their study doctor.
• Male participants should use adequate forms of birth control with their partners.
• Currently breastfeeding
• Current or recent use of NAC
• Contraindications to dexamethasone or N-Acetyl Cysteine (NAC). These include:
• Previous intolerance or allergy to dexamethasone or NAC
• Scleroderma
• Active infection
• Glaucoma
• Psychiatric disorder that could be exacerbated by dexamethasone
• Cystinuria
• Any other condition that the treating physician believes to be a contraindication to dexamethasone or NAC