World Cancer Day 2013: Is a Cure Within Sight?

When people think of big advances in medicine, they tend to think of things like the cure for AIDS, the cure for the common cold, and the cure for cancer. However, cancer is not a single disease. In fact, the National Cancer Institute lists hundreds of different types of cancer.  Many have the same treatment methods such as surgery, chemotherapy, radiation, etc.   However, this is an oversimplification. Consequently, there is no single "cure for cancer" because it is a class of diseases with a common definition: "The uncontrolled division of abnormal cells in a part of the body."

The most effective way to deal with cancer is prevention. For example, approximately 16% of cancers are caused by viruses and bacteria such as hepatitis-induced liver cancer and Human Papillomavirus-induced cervical cancer. Vaccines against hepatitis are intended to prevent this serious and life threatening disease, but the other benefit is protection against some forms of liver cancer. However, HPV is a relatively minor disease except for the increased risk of cancer in women. Consequently, vaccines like Gardasil can be viewed primarily as an immunization against some forms of cancer. If only there were a single vaccine against "cancer."

Similarly, many other forms of cancer are related to habits and preventable conditions such as tobacco, alcohol, obesity, poor nutrition, etc. Habits are difficult to address. However, some bad habits are on the decline. Seventy years ago around 60% of the U.S. adult population smoked. Today around 80% of the population is tobacco free, reducing the population's risk for lung, mouth, and throat cancers. In some ways, this has been offset by obesity and other preventable causes — including environmental exposures.

Many cancers now have an emerging genetic link such as breast cancer. As genetic testing becomes more robust, it will become possible to put people on preventative or screening regimes as children or young adults to lower the likelihood they will develop cancer later in life.

Along with prevention, the next most effective strategy is early detection. The survival rate for almost all cancers goes up dramatically when detected early. The survival rate for cancers that have metastasized is in general very low. Medicine has taken great leaps forward in detecting cancer early, but this also depends on the type of cancer and form it takes. Many forms of cancer have no direct test. However, there is now a counter-intuitive but data-backed trend showing that excessive screening may not save lives. The National Cancer Institute has shown that the overuse of screening has actually exposed patients to unnecessary treatment without a measurable benefit. Screening policies will require some balancing to determine what helps patients the most.

Technology has made huge leaps forward in the treatment of cancer. For example, since doctors can now determine if a breast cancer is hormone sensitive, traditional treatments can be combined with hormone blockers, greatly improving outcomes. Similarly, targeted drugs based on genetic profiles and other individual patient factors can make cancer treatments much more effective. 

As a result of better detection and better treatment, cancer survival rates have more than doubled over the past 30 years. While it might be sad to think there will never be a single "cure for cancer," each decade brings significant incremental improvement.  It is likely that eventually most cancers will be no more dangerous than kidney stones

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