The reality in this case is very different from what you perceive it to be.
How old is your dad? Is the cancer localized or has it spread? What's his health like? Are there any symptoms? Was he sick often in his life? All these things play a role, but most important one right now is: has it spread elsewhere?
The cells in our body mutate often, but our immune system beats them every time. It's when it doesn't manage to beat them that they can become cancerous, and from then on they seem friendly to our immune system.
Cancerous cells are weaker then healthy cells. The basic principle on which many chemotherapeutic agents work is that if we flood the whole body with a cell-destroying poison, the first ones that are going to die are the weakest ones. Of course, many healthy ones will die too (hence the loss of hair and all the other complications), but the healthy ones may regenerate...
If the cancer hasn't spread, most common choice is to surgically remove it, and then hope the immune system will do it's job in life aferwards.
It would be very wise at this point to spend time reading everything there is about his condition, and understand it thoroughly, so that you know exactly where each choice you make could take you.
I would ask his oncologist..
Different types of doctors often work together to create a patient’s overall treatment plan that usually includes or combines different types of treatments. Systemic chemotherapy gets into the bloodstream to reach cancer cells throughout the body. A patient may receive one drug at a time or combinations of different drugs at the same time. you should talk with your health care team to understand when to call your doctor about side effects. Read more about managing side effects. The side effects from chemotherapy usually go away once treatment is finished.
Xelox regimen (Oxaliplatin as infusion and Capecitabine as tablets) are given for advanced stage colorectal cancer. Please discuss with your doctor and read more about the sideeffects of Xelox, hairfall doesn't happen in this chemo.