In stage 4 colon cancer if appetite is poor / gone down , does this mean it's terminal ?

In most progressive: advanced diseases, apatite eventually ↓es. Few current treatments (unlike immune system) precisely target only Ca cells. Both Ca drives ↓ apatite, as do many Ca treatments, due to damage to healthy cells, yet there are always lots of individual variables. In any state of health, enough ↓ in nutritional intake makes it increasingly difficult to impossible to maintain body functions & stay alive.

Wasting syndrome: Many cancers cause appetite supression and an altered metobolism leading to weight loss. This is not limited to late stage disease, but certainly does impact the resiliency with which a person can endure added treatments and maintain stamina to continue to live. Some treatments also supress the appetite or cause ulcers/pain that reduces desire and taste. Do the best to get calories in to sustain,