The obvious ones are radiotherapy and chemotherapy. There are drugs availiable too, such as herceptin specifically for breast cancer. For detailed info I'd google it or see a doctor
Radiotherapy can cause cancer but you would have to have radiotherapy non-stop through out your live but just a little bit of radiotherapy will only damage tiny bits of tissue that will repair thwm...
They can use many treatments. The treatment they use the most is kemo. The doctors put the kemo into your body's blood system to help your white blood cells keep the cancer cells out of your body.