4 Reasons We Haven’t Cured Cancer Yet

And 1 really good reason to be hopeful.

In 1971, President Richard Nixon signed the National Cancer Act, starting the war on cancer. Since then, doctors and researchers have conducted a tremendous amount of research, backed by billions of dollars in funding. There have been many successes, and the U.S. cancer death rate fell 23% from 1991 to 2012—which translates into 1.7 million averted deaths. Still, we are far from winning the war on cancer; cancer remains the number two killer of Americans after heart disease. So, you may be wondering, why hasn’t there been a cure?

Below are four major reasons—although these are certainly not the only reasons—why cancer has not been cured. In addition, I offer one key factor that is helping researchers overcome these hurdles and leading to accelerated advances. 

1.      Cancer is not a single disease.

Cancer is not a disease. It is many, many diseases—hundreds of distinct disease in fact. Cancer is defined as abnormal cells that divide uncontrollably and spread. This process can start almost anywhere in the body—the lungs, brain, blood, bone, etc.—and these different cancers can be quite different. Each type of cancer has its own symptoms and risk factors, and the various types demand different screenings, diagnostics, and treatments. Some cancers are much more difficult to diagnose or treat than others. For example, the blood–brain barrier makes treating brain cancer with chemotherapy drugs extremely challenging. This is one of many reasons why the five-year survival of brain cancer is significantly lower than for other cancers, such as breast cancer. In addition, some cancers are more aggressive, growing and spreading (metastasizing) rapidly, while some may grow so slowly they never harm the patient.

However, all cancers that occur in a certain organ, such as the brain, are not the same either. Within each cancer classification, there are further types. For example, while 85% of lung cancers are known as non-small cell lung cancer, there is also small cell lung cancer and lung carcinoid tumors. Among non-small cell lung cancer, there are further subtypes: squamous-cell carcinoma, adenocarcinoma, and large-cell carcinoma. Each type demands different treatments. Hence, there can be no single cure to cancer, because there is no single cancer.

2.      Each tumor is unique.

The diversity of cancer extends even beyond types and subtypes—the cells that compose a tumor may be heterogenous, meaning that cells with different mutations make up the same tumor. This diversity means that a single treatment may not be able to kill all the cells. Cells that are resistant to the treatment will survive and regrow the tumor. As a result, combination treatments are often necessary to treat even a single cancer.

Cancer is also dynamic. Tumors can spread from one area of the body to another, forming metastatic tumors, and the metastatic tumors may respond differently to treatment than the original tumor did. Dr. Rosandra Kaplan, M.D., head of the Tumor Microenvironment Section in the National Cancer Institute’s Center for Cancer Research, notes that “primary and metastatic tumors from the same patient can actually be quite different at the genetic and epigenetic level.” This variation makes eliminating the tumors an extreme challenge.

3.      There are a multitude of risk factors.

There is no single cause of cancer; no single infectious agent or gene is at the root of all cancers. Instead, cancer is the result of complicated interactions between inherited genetic mutations and environmental factors, such as exposure to cancer viruses or carcinogens. Many of the specific mutations have been identified. About 180 different genetic mutations have been associated with breast cancer, and scientists have determined that more than 30% of all human cancers are driven by mutations of the RAS family of genes. However, having one of these mutations far from guarantees that the individual will get cancer. According to the National Cancer Institute (NCI), 55%–65% of women who inherit a BRCA1 genetic mutation will develop breast cancer by age 70. While these numbers are high, it still means 35%–45% of women with this mutation do not develop the disease.

Other risk factors, including diet, obesity, and tobacco use, are important environmental risk factors for cancer. According to the Centers for Disease Control and Prevention (CDC), 80%–90% of lung cancers in the United States is linked to cigarette smoking, yet some people who smoke all their lives never develop cancer, demonstrating that other underlying factors are also at work. Other environmental factors such as radon, asbestos, and other pollutants can also contribute to lung cancer as well as other cancers.

These numerous risk factors make it immensely difficult to understand, prevent, or treat cancer.

4.      Cancer is produced from the body’s own cells.

Because cancer is produced from the body’s own cells, the body’s immune system often has difficulty recognizing the cancer cells as a threat. In addition, some cancer cells can produce substances that keep the immune system in check. As a result, there is a limited immune response against the cancerous cells.

For the same reason, developing treatments that can kill the cancer without hurting the patient is extremely difficult. Hence, current treatments often damage healthy cells along with the cancer cells. Chemotherapy treatments are well known for their harsh side effects, and radiation can cause mutations in the surrounding tissue as well.

To help combat this problem, researchers are developing novel immunotherapy treatments that use the immune system to fight the cancer. These therapies can help boost immune system functions or specifically train the patient’s immune system to attack the cancer cells. However, many of these therapies are still in the experimental phase, and most have demonstrated efficacy in only a limit group of patients and cancer types.

One Reason to be Hopeful

1.      Collaborations and partnerships are accelerating research and driving results.

Cancer is a difficult problem mainly because it is so vast and diverse. Hence, partnerships and collaborations offer the key to winning this war. While it is impossible to develop a one-size-fits all cure for cancer, that doesn’t mean it’s impossible to beat. While there are many types of cancer, there are also many researchers studying the disease in its many forms. Bringing together these groups helps them make use of the best-available technologies and share knowledge—and ultimately accelerate research.

Medical and scientific research have long required team efforts. You only need to look at the massive list of names included in the acknowledgement slide on any scientific presentation to realize that research requires many scientists—often spanning across multiple institutions and sectors as well as countries and continents. These collaborations allow researchers to attack cancer from all sides—with basic, translational, and clinical research—and with more cost-efficient and time-efficient processes. They also allow investigators to more easily share lessons learned from one cancer or therapy to another.

Several recent large research collaborations highlight the benefits of these partnerships. Recently, 550 researchers from 300 institutions around the world combined forces to discover 72 previously unknown gene mutations that lead to the development of breast cancer. Through this extensive effort, they were able to study blood samples from nearly 300,000 women from which they could pull novel insight. In October, the National Institute of Health, Foundation for the National Institutes of Health, and 11 biopharmaceutical companies launched a public–private research collaboration called the Partnership for Accelerating Cancer Therapies (PACT). The PACT, which is working to advance new immunotherapy treatments that harness the immune system to attack cancer, is part of the Cancer Moonshot. Cancer Moonshot is an effort to bring together resources across the federal government to accomplish 10 years of cancer research in just 5 years. These efforts both highlight how collaborations are driving results.

In additions, research collaborations are increasingly bringing in new partners from outside the traditional cancer research space. These partners, in turn, bring new capabilities and expertise to the cancer research table. For example, the recently announced Accelerating Therapeutics for Opportunities in Medicine (ATOM) consortium brings together the data and cancer and drug-development expertise of NCI’s Frederick National Laboratory for Cancer Research (FNLCR), GSK, and the University of California–San Francisco with the supercomputing power of the U.S. Department of Energy’s Lawrence Livermore National Laboratory to accelerate cancer research. This effort is specifically designed to slash the time it takes for preclinical oncology drug discovery from six years to just one. This breakthrough would facilitate many more timely cancer breakthroughs.

Cancer represents a complex and massive scientific and organizational challenge—one that no single organization can hope to tackle alone. Researchers and organizations realize that collaborations are key, and these powerful research collaborations are emerging and growing, enabling incredible advances in the cancer research space.

Frederick National Laboratory for Cancer Research

The Frederick National Laboratory for Cancer Research is a shared national resource whose mission is to enable solutions to biomedical research questions and overcome challenges to progress. If you are interested in collaborating with the Lab, learn more here.