Radiation fatigue - Mum's Lung Cancer

Hello

Please can someone help.

My mum was diagnosed with stage 3b NSCLC last April. She had chemo/immunotherapy, which intially helped but after her last scan it showed progression and they said it was not working. The main tumour had gown and there was futher spread in the chest, although no spread anywhere else.

We saw her consultant, who told us that he didn't think second line treatment would add any benefit and that we should consider quality of life against the side effects of treament. He was happy to agree to more treatment as long as mum felt able and wanted to continue, which she does. So the plan was that she would have 5 radiotherapy sessions over five consecutive days to shrink the main tumour and then chemo with another drug.

Mum had the radiotherapy sessions two weeks ago and although she was fine at the time, after 4 days of the treatment finishing, she was knocked for six with fatigue. (Extreme fatigue had been her only side effect of the previous chemo too.) The fatigue is debiltating; she struggled to get out of bed for a couple of days and although she can now get up and go to other rooms in her apartment, it leaves her worn out. She is also breathless too. She is definitely not up to the chemo right now.

My question is, can radiotherapy really cause such extreme fatigue? It has been 11 days now. Has anyone else experienced this level of fatigue and managed to get over it? I am so scared that it's not the radiation but the cancer getting worse. Also, the radiation was supposed to help with her voice, which had become hoarse, and her slight breatlessness, but that still seems the same or a little worse. Would that not have improved by now?

We know there's no cure, but really thought we could manage it for a while.

If anyone can reassure or offer any experience I would really apprecitae it.

Thanks x