Modeling a Future without Cancer
Declines continue. When it comes to cancer rates, those two words are always encouraging. In fact, they were the headline attached to most news stories last week reporting the release of the 2009 Report to the Nation on the Status of Cancer. Understanding that this is not just a single year’s trend, as the report made clear, but that many cancer rates have been on the decline for more than a decade, is particularly encouraging.
While progress against cancer—lower rates of new cancer cases and of cancer deaths—is welcome news at any time, I daresay none of us at NCI considers modest but steady progress to be sufficient. We must continue every effort to develop new understandings and comprehensive solutions to complex diseases. Yet, the report also makes a convincing case that we must work even harder to fully employ today’s best methods of treatment and cancer risk reduction.
This year’s report includes a special feature, which uses incidence and mortality modeling projections to show that colorectal cancer mortality could fall by as much as 50 percent by 2020 if many more Americans have regular colorectal cancer exams, exercise more, eat more healthily, and stop smoking, among other things. The potential benefit is stunning when you consider that it’s estimated that colorectal cancer will take nearly 50,000 lives in the United States in 2009. Clearly, community-based programs of NCI and its partner agencies must even more strongly promote screening, improved nutrition, and smoking cessation.
In colorectal cancer, even applying today’s adjuvant chemotherapy regimens to more patients could have a major impact. In their modeling efforts for the report, researchers assessed data on use of, and disease-free survival rates associated with, four chemotherapy regimens used to treat advanced colorectal cancer during different historical time periods. Just increasing conventional colorectal cancer treatment rates over time—from 8 percent of patients in 2005, to between 45 percent and 83 percent of patients by 2020—would have a significant impact on colorectal cancer mortality.
We often talk about a highly personalized approach to cancer research, patient diagnosis, and the development of biomarkers and targeted therapies, all tied to the unique cancer burdens of individuals. As this report strongly highlights, by applying some very straightforward actions that we know are effective today, and using them efficiently, we can make perhaps an equally large dent in the cancer burden. This will truly complement the benefit over the coming decade likely to be derived from targeted chemotherapy agents currently in the research and development pipeline.
For proof of that point, one needs look no further than lung cancer. Many have hypothesized that if we immediately got every smoker in America to quit, the overall death rate in the United States due to tobacco-related cancer could be cut in half.
There is one other area in which I have become convinced we have a great chance to dramatically impact cancer incidence and mortality: infectious agents. Current evidence indicates that as many as one in five cancers have an infectious cause. My belief is that with an increased effort, research addressing how viruses or bacteria can impact cancer causation may continue to give us significant opportunities to reduce incidence and mortality.
In fact, more than a dozen viruses already have been associated with various types of cancer. Researchers are still learning how a cell that is infected with a virus becomes a cancer cell. Hepatitis B and C have been linked to liver cancer conclusively and there are several cancers, including cervical cancer, that are associated with the human papillomavirus (HPV). Additionally, Helicobacter pylori has been linked to stomach cancer and several viruses have been associated with leukemia, lymphoma, and Kaposi sarcoma. Scientists are currently examining potential connections between some viruses and brain, colon, breast, and prostate cancer, although no definitive associations have been established yet for these diseases.
Identifying, treating, and even possibly preventing cancers caused by infectious agents such as retroviruses are ongoing challenges, because each virus causes cancer through a different process and some viruses cause cancer indirectly. Each day we are gaining a better understanding of the relationship between infection, immunity, and genetics. With this new understanding, we are beginning to develop new therapies and novel vaccines that target viruses, which could help lower the number of cancers that are associated with infections.
One of our great areas of promise in addressing the cancer burden comes from the intense study of the genetic and epigenetic alterations associated with the initiation and progression of cancer. The Cancer Genome Atlas (TCGA) project, a joint effort of NCI and the National Human Genome Research Institute, has been an extremely successful pilot that continues to unveil the genetic alterations, translocations, and mutations of a growing list of cancers. Using this comprehensive dataset may also provide unique insights into telltale signs of infectious agents.
During this past decade we have clearly broadened and deepened the tools that we have available to fight cancer. By effectively using these tools in the coming decade, we have an excellent opportunity to truly accelerate the rate of decline for many types of cancer. We are entering the second decade of the 21st century with a strong hope of reaching the goal of making many cancers chronic diseases, at worst, and memories of a bygone era, at best.
Dr. John E. Niederhuber
Director, National Cancer Institute