Not all chemo meds make you lose your hair. My youngest son, age 48 at the time was on two different kinds of chemo for 6 months after having two bi-sections of his colon to remove cancerous polyps, and he didn't lose his hair. They also took out about 70 of the surrounding lymph nodes during the surgery. He did unfortunately end up with a blood clot in his lung and had to give himself shots of Heparin through the remainder of his treatments. He also ended up with bad neuropathy in his hands and feed from the chemo. The neuropathy in his hands went away about two years later, but he still has bad neuropathy in his feet. The good news is that he just got his five-year clearance, and is now considered a cancer survivor.
Everyone I know who lost their hair during chemo grew it back as good as ever later.
Congratulations to your son, mass55th. That’s great to hear.