My sister asked if I would pose this question for her. My sisters dog Roxy is a 7/12 year old boxer mix that was just diagnosed with an aggressive form of lymphoma. She is so confused on what to do. She was wondering if she puts her dog through chemo will she make her dog just suffer for nothing or will it make a difference in roxy's quality of life? She wants the best for her dog and does not want her to suffer. Any honest feedback will be appreciated.

Chemotherapy in animals is very different than in people. In human medicine, the goal is cure, regardless of what side effects it may cause. The human patient can understand that they may have do endure some bad times in the hope of long-term results.
In animals, the goal of chemo is to achieve and maintain good quality of life. If the medicine makes the dog sick, they usually will try another form of treatment.
Your sister should probably discuss the whole process with a veterinary cancer specialist. Even if the treatments are done locally, the specialist will be able to thoroughly explain what side effects are possible and what they are hoping to gain in terms of length and quality of life.
I wish Roxy well, I hope they can help her.