To me, that depends on what you consider a "cure" to be. Mainstream medicine considers a cure to merely be 5 years survival from the time of diagnosis (and never mind if your body is riddled with cancer and you die the week following your 5 year anniversary). I consider a cure to be not only completely getting rid of cancer, but also to preventing it from ever returning and going on to live a relatively normal and health lifespan. Doing that will require more than just a couple or more supplements or herbs or such.
Lots of natural things are very good for eliminating cancer. However, to completely "cure" cancer once an for all requires eliminating existing toxins and avoiding future ones, as well as building up the natural immune system that is our first line of defense against cancer and other illness, and basically adopting a healthy anti-cancer diet and lifestyle and getting optimal nutrition for the rest of your life.
Put another way, getting cancer should be a permanent life-changing experience that does not stop when the cancer is gone (or apparently gone, as is often the case). Though a person may not need to have an intensive anti-cancer protocol going on for the rest of their life (I suggest at least 6 months and preferably a year after the cancer is no longer detectable), they should nevertheless live very healthily and never go back to the diet and habits that enabled cancer to gain a foothold in the first place.