Is it possible to have diffuse, bilateral pulmonary fibrosis as a late side effect of unilateral radiation therapy for breast cancer?

The only context you may see this is in a patient with underlying Interstitial Lung Disease (ILD). I had a woman with a small pulmonary nodule adjacent to the heart and was unresectable. She had moderately severe ILD, and I used a proton plan to try and keep the low dose RT out of the rest of the lung. The plan looked great, but her ILD flared in both lungs. Fortunately the flare subsided and her lung function, while worse, has been pretty stable. In my case the ILD developed with a honeycombing pattern and worse in the bases as compared to the upper lobes. This was pretty similar to this report. I stuck a pic from the interwebs to show the pattern below.

My guess is that the inflammation of the RT causes a more widespread exacerbation of I...

I have seen fibrosis within and outside radiation field, but diffuse bilateral fibrosis would be very unusual. One should look for different causes for this, including the effects of systemic treatment like herceptin.

I have had a case of a lady with this clinical picture which later was diagnosed with BOOP. The clinical picture is very much like bilateral pneumonitis.