Sorry to hear that Fisky. Tagging on to old guy II. I pulled up the treatment options for your disease, of course unsure how accurate it is. That said, one treatment option is immunotherapy. I was treated with both immunotherapy and chemotherapy initially, then radiation. In some variants of my disease the sole treatment is the immunotherapy Rituxan. This would be the preferred remedy, if it does the trick.
My disease was aggressive yet curable, so the oncology team thru all options. I am quite a bit stronger 3 years post treatment. I would assume if immunotherapy is an option it will be a quick fix. Anthracycline chemotherapy kill rapidly multiplying cells; in my case targeting B-cells in the lymphatic system. For me the chemotherapy included steroids that resulted in 35 lbs weight gain. Steroids were to support the body during treatment periods where my red blood cells were depleted. I was given Claritin for bone aches while the bone marrow is keeping up with the depletion. Sounds strange a allergy drug, but it worked. I forced myself to park a mile from my office so I could get some exercise. Challenges were not crapping myself on the way in or too tired to make it to my car. I have lost about 25lbs, but not back to where I was. Chemotherapy is tough, no doubt about it. One would have to have more fortitude than I to train thru it. Radiation just makes you tired an hour or two after treatment, but they string those together over a period of weeks Monday thru Friday. Mine was a four week period. I could train through this period; not normal but tolerable. So, severity: 1) chemotherapy, 2) immunotherapy, 3) immunotherapy.
In answer to your question, I feel I can be nationally competitive, but at this point untested. In January 2018 shortly before diagnosis I had one of the top early season indoor times M65 800m 2:59 and mile 6:32. A month after completing chemotherapy I ran a 7:22 1500 meters. It was the most difficult race in my life; could not catch my breath.
Probably too much information, but the experience is a lasting memory, though more positive than negative.
Currently I am sitting in the hospital while my wife recovers from major surgery; non-cancer related, and something that is hopefully behind her. As she said “you eat well, exercise and still....”
Best wishes.
Igy