What do Supreme Court Justice Ruth Bader Ginsburg, actor Patrick Swayze, cultural anthropologist Margaret Mead, opera singer Luciano Pavarotti, business executive Steve Jobs, astronaut Sally Ride, and CBS producer Don Hewitt have in common? All were diagnosed with pancreatic cancer, but the only one to survive after treatment was Ginsburg (whose pancreatic cancer was discovered at a very early stage, in a routine follow-up exam after successful colon cancer treatment).
Pancreatic cancer is most commonly fatal, largely because there are so few early symptoms that allow detection before it has spread and because it tends to resist chemotherapy. Estimated to be the fourth highest cause of cancer deaths in the United States in 2015, pancreatic cancer will kill over 40,500 people this year, according to the American Cancer Society's "2015 Cancer Facts and Figures" report. Overall one-year and five-year survival rates are 15 percent and 2 percent, respectively, with results only slightly better for the very small percentage of patients (like Justice Ginsburg) whose disease is discovered early.
Now there are two important sources of hope for both diagnosis and treatment of pancreatic cancer.
Diagnosis. On June 24, 2015, the University of Texas M.D. Anderson Cancer Center announced the discovery of a potential blood test that detected a large molecule (a protein called glypican-1) in the blood of a small number of patients that indicated "with perfect accuracy and no false positives, the presence of pancreatic cancer." The test was also able to differentiate benign pancreatic disease from cancer. If such dramatic results can be achieved in large-scale clinical trials, the test could spur development of new medical and surgical options for treatment of early-stage pancreatic cancer.
Treatment. Once detected, the next challenge is finding an effective treatment. Promise may emerge from long-standing marine biology research seeking organisms that have functional properties resembling those of proven cancer treatments. The focus of such studies is on identifying substances that can:
- Stop the development of blood vessels that feed tumor growth.
- Inhibit replication of the DNA involved in tumor growth.
- Kill rapidly dividing cells without damaging healthy ones.
- Block chemical signals that trigger or sustain metastasis.
Labs have been exploring both terrestrial and marine flora and fauna for medicinal purposes for decades. For example, Taxol's discovery as a cancer drug in 1964 emerged from such work with National Cancer Institute (NCI) support when a substance extracted from the bark of the Pacific yew tree was found to have cancer-fighting properties. Marine life could be especially productive as a source for future drug development because the variety of species is so broad, so few (perhaps only 10 percent) have yet been investigated for therapeutic potential, and the intensive ecological pressures on deep sea organisms makes substances derived from them particularly "bioactive."
According to articles in a variety of scientific journals, numerous substances extracted from marine life (including fungi, sponges, algae, mollusks, "sea squirts," coral, and seaweed) have potential to fight other kinds of challenging cancers. In part, this is because the toxins these organisms use for their own defense must be strong because they have to function in diluted form.
Two examples are specific to pancreatic cancer:
- Substances that can change the pancreatic tumor's microenvironment in ways that prevent tumors from growing and metastasizing are the focus of Esther Guzmàn, associate research professor at Florida Atlantic University's Marine Biomedical Biotechnology Research Program. Her team has identified over 100 natural marine substances that have potential to control tumor invasiveness and reduce the metastatic process that is so toxic in pancreatic cancer patients.
- In 2013, another lab's study of five different brown seaweeds demonstrated "for the first time" the presence of substances that "effectively target key molecular players of [pancreatic cancer's] progression" and have the potential to reduce tumor progression and metastasis in pancreatic cancer.
Yet discovering the cancer-killing molecules is only the beginning of the drug development process. Dr. William C. Phelps, director of preclinical and translational research for the American Cancer Society, explains that:
"Once such substances are discovered, development of synthetic forms may be required to provide access to the substances in amounts sufficient to support clinical testing and widespread patient use. Synthetic forms can also provide opportunities for modifications to the original molecule to make it more potent, more bioavailable, and longer lasting in the human body."
Basic research is needed to learn why such marine substances might be toxic to some kinds of cancer cells and not to others, how the substances interact with chemical signals within the human body that trigger or stop cancer's growth, and how such substances affect normal cells. Such work may well reveal which cancers these discoveries might help. For instance, tunicates (sea squirts), which are among the most common marine invertebrates, have the unusual ability to correct cellular abnormalities over a series of generations and to regenerate damaged tissue; the implications for treating various cancers could be significant.
For the most problematic cancers, like pancreatic, marine organisms offer some hope where little has existed to date, Dr. Phelps reiterates that this kind of research isn't new, but that it's an important complement to other types of research currently underway:
"We will continue to look for 'any port in the storm' for pancreatic cancer, whether that be immunotherapy, combinations of conventional therapies, targeted therapies, natural products, gene therapy, oncoviruses, and so on. Everything has to be on the table because little is working."
Marine biology's promise as a source for new pancreatic cancer treatment options can be realized and thousands of lives saved in the long term only if citizens are willing to demand that Congress sustain investment in such research initiatives by government bodies (National Cancer Institute, National Science Foundation, National Oceanographic and Atmospheric Administration, and so on). Progress depends on proliferation of research initiatives and on funding them for long enough to fully explore their life-saving potential.