If I were a cancer patient, I would definitely weigh in my options. Personally, I believe in living your life happily. Even though I would have a limited amount of time left to live if I was diagnosed with cancer, I could still live every last second of it to the fullest, as well as being more motivated to try the things I never did but always wanted. I don't believe that the last seconds of your life should be spent in a hospital writhing in pain and agony, as you come to regret not doing the things you should have done. I understand that there are people who I need to fight for, to live for, especially if I had children who were waiting for me at home. However, if the circumstances were similar to my current situation of living with two parents, I would probably not consider chemotherapy, because my parents and I both have similar opinions of being happy in life, and I would rather have them not see me suffering through chemotherapy. If there was someone that I had to live for, on the other hand, then I am left with no choice but to go through with the treatment.
Although, regardless of the circumstances, it really is your life. And even though you have obligations and attachments to others, if you're not happy with what you are doing, and you know that you'll end up regretting the choices you make, then it's up to you to make the final decision, despite how selfish the entire act seems.
In the end, due to strong opinions about chemotherapy, I suppose it really isn't such an effective "cure" to cancer. Perhaps if the treatment of cancer would continuously be improved overtime, so that there are less and less disadvantages, (such as the chance of death that comes with the treatment), and be more favoured as a cure to cancer.