there is an equivocal role of chronic exercise in modulating cachexia and other associated dysfunction. exercise is proposed as a complementary treatment in cancer through ant inflammatory effect and metabolism-modulating mechanism.
In my opinion, there will be an inverse relation between exercise and cachexia progression at least in early staged cancer patients, although it may vary from tumor to tumor subtype.
It is possible to reverse cachexia by exercise, but several factors can influence the final outcome, like cancer type and stage, general condition of the patient, type and duration of the exercise etc. At least one definitive study is required to establish exercise as a treatment for each type of cancer, which should also include effect of exercise on different stages of that cancer.