Cancers are being cured, and they are being prevented. I have cancer caused by the HPV virus. If the HPV vaccine was available when I was a kid, I would not have contracted cancer at this point in my life. My dad hang lung and then esophageal cancer, but he was a smoker for decades. I don't smoke, so I doubt that I will ever contract these.
Doctors are making tremendous advances, but the tools used to look at the genetics of cancer are still fairly young. The first therapeutic drug aimed at cancer genetics was Herceptin, which was approved for treatment in 1998. It revolutionized breast cancer treatment for women with a specific form of the cancer, but it is useless otherwise. When I was undergoing treatment this year, I was given a drug that got my immune system to fight the cancer that had only been on the market for 5 years.
Recently, a team of doctors looked at the genetics of a certain type of breast cancer, and found almost no similarities in the genetics of the tumors, so a single gene-targeting drug can't be developed.