Assessment of Precision Irradiation in Early NSCLC and Interstitial Lung Disease

Inclusion Criteria:

* Stage T1-2, N0, M0 (AJCC Staging, 8th Edition - i.e. tumor size ≤ 5 cm) prior to registration.
* Not a candidate for surgical resection, determined by any of the following:
* Consultation with a thoracic surgeon
* Discussion at Multidisciplinary Team (MDT) rounds with a surgeon present
* Patient refusal of surgery
* Pathologically (histologically or cytologically) proven diagnosis of non-small cell lung cancer (NSCLC) 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 a primary NSCLC.
* Eastern Cooperative Oncology Group (ECOG) performance status 0-3;
* Age ≥ 18;
* Life expectancy \> 6 months
* Fibrotic interstitial lung disease of any subtype, as diagnosed by a respirologist/pulmonologist.

Exclusion Criteria:

* Prior invasive malignancy (except non-melanomatous skin cancer) unless disease free for a minimum of 2 years (e.g., carcinomas in situ of the breast, oral cavity, or cervix are permissible); previous lung cancer, if the patient is disease-free for a minimum of 2 years is permitted.
* Prior thoracic radiotherapy
* Plans for the patient to receive other local therapy while on this study, except at disease progression;
* Plans for the patient to receive systemic therapy (including standard chemotherapy or biologic targeted agents), while on this study, except at disease progression. Patients are allowed to receive anti-fibrotic agents used in the treatment of IPF or non-IPF fibrotic ILD (e.g. nintedanib, pirfenidone), or steroids, 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 treatment.
* Active pregnancy
* Concurrent administration of any drugs with known radiosensitive effects (e.g. Methotrexate).