Everyone I know who lost their hair during chemo grew it back as good as ever later.
I've heard that is true. I have a cousin by marriage who had breast cancer, and went through chemo, lost her hair, and it grew back even thicker than it was before. She's a cancer survivor as her surgery and treatment was more than 15 years ago. My poor sister had chemo and radiation for lung cancer back in 2010. She had her hair all shaved off before she started the treatments. When her hair finally started growing back in, they sent her for 10 radiation treatments on her brain to prevent the cancer from going there, and she lost it all again. Of course she didn't make it, went to hospice care, and passed away on her birthday in September 2011.
Years ago, our good friend had throat cancer, I believe it was stage four. (mercifully he’s doing great right now.) He had chemo and radiation and lost all his hair. We didn’t see him in the neighborhood for quite a while obviously. When he felt well enough to come out to socialize after several months, his hair was growing back so well, we all joked that he was really doing Hair Club for Men this whole time and not chemo :).