Cancer Options?

I am a 48 year old female with cancer. I've been told that based on my mammogram it is small. I'm confused about all of the different treatment options. Should I have my whole taken off or just part of it? Will I need chemotherapy? Do I need radiation treatments? I have seen advertised one week of radiation but my cousin who also had cancer said she had almost 7 weeks? I want to do what is best, but find it all confusing.