Everyone is different, but we have hope things are moving for the better as medical options advance through clinical trials.

When I was originally diagnosed as Stage-II (and resectable) almost two years ago at age 58, the oncologist predicted I had "at least" two years ahead of me, and longer if six months of Folfirinox and the Whipple surgery to resect a single tumor, being in the head of my pancreas was curative.

Although it appeared to be "curative" by all measures, the cancer reappeared at the original surgery site 3.5 months later, and then in multiple other areas (liver, peritoneum; i.e.m Stage-IV) in the months that followed.

I resumed chemo (standard of care drugs Abraxane + Gemcitabine + Cisplatin; not any clinical trial drugs) the week of my 60th birthday (end of January). It has now been 9.5 months since the recurrence; 7 months since it was confirmed metastatic/Stage-IV; 6.5 months of biweekly chemo (15 rounds so far), and I'm really not showing any signs of cancer in my overall health, just 3-4 days of post-chemo fatigue and nausea related to the treatment.

Noticeable decline in muscle tone and cardio fitness mostly related to reduced exercise over the past year, but I do still enjoy riding my skateboard down a big hill on the outskirts of town every few weeks. The ride downhill is easy; it's the walk back up that wears me out. But I give a big middle finger to cancer every time I do it. Gotta find some moments to savor!

My only issue with balance is from the chemo-induced neuropathy in my feet. If your hubby's chemo cocktail includes abraxane, cisplatin, or oxaliplatin, he might want to consider compression socks and compression gloves during chemo. Icing may also help, but might be better to avoid if oxaliplatin is in the cocktail, due to the hyper cold-sensitivity it induces.
https://www.breastcancer.org/research-news/hand-cooling-compression-nearly-halve-risk-of-neuropathy-from-chemotherapy