For mid-stage colon cancer, chemo followed by surgery does offer a better chance than surgery alone, see e.g. http://www.medscape.com/viewarticle/587852 As of your parents...keep talking to them about the medical stuff, for if they lie it got to show up in the details. Pay attention to nutrition & control the side effects as much as possible . If the patient cannot tolerate anymore then chemo should be stopped.