These Questions originally appeared on Quora - the knowledge sharing network where compelling questions are answered by people with unique insights.
Answers by William G. Nelson, M.D., Ph.D., Director of the Johns Hopkins Kimmel Cancer Center, on Quora.
Q: What makes cancer so hard to solve?
A: Cancer is a collection of many diseases characterized by the uncontrolled growth of cells that usually arises from changes in DNA (mutations). Because of mutations, the processes that normally tell our cells when to start and stop multiplication and growth go awry. The biology of cancer, from the number and type of mutations that flip the switch to uncontrolled growth to the influence of non-cancerous cells that surround the cancer cells, is very complicated, making it difficult to solve. In any single tumor, there can be more than 100 genes that are mutated. The patterns of these mutations differ from cell to cell and from patient to patient. In addition, cancer cells are adaptive. They can circumvent therapies and become resistant to drugs, which makes treating cancer much more difficult. The more we know about the biology of cancer, the more precisely we can prevent, detect, diagnose, and treat it.
Q: What are the most promising medical research efforts taking place today aimed at finding a cure for cancer?
A: Two important areas of clinical research, which have come up in other questions, that are making major strides in clinical trials and new drug approvals are precision medicine and immunotherapy. Precision medicine involves giving the right treatment to the right patient at the right time. This includes using the precise genetic and molecular make up of patients' tumors to guide treatment. Another promising area is immunotherapy, using the body's immune system to attack cancer. Several new immunotherapy drugs have been approved by the FDA, with indications in cancers once never thought to be susceptible to these types of drugs. The two approaches are also being combined so that immunotherapy is personalized to individual patients. More on the research side, one area that is turning up in many laboratories is the technology called CRISPR. This technology allows a researcher to edit genes, to modify the genome in cells in a dish, to potentially alter or correct the "bad" mutations that contribute to disease. So far, CRISPR has been used with great success in the laboratory to address research questions about the genetics and biology of cancer. It is not currently used to treat patients and there is much to be learned about using the technology in humans. However, in due course, clinical trials using this technology are likely. Another exciting area of medical research is engineering viruses to attack cancer. With the FDA recently approving Imlygic, a genetically engineered herpes virus to treat melanoma, and many other viruses being tested in clinical trials for different types of cancer, oncolytic viruses are becoming the new class of anti-cancer therapies.
Q: I'm 20 years old. What decisions can I make over the next 20 years to avoid cancer?
A: You are very wise to think ahead. The most important thing you can do, of course, is to avoid use of tobacco in any form. Lung cancer is the leading cause of cancer death in the U.S. for both men and women, and people who smoke are 25 times more likely to develop lung cancer than those who don't. Tobacco use is also associated with increased risk of 18 different cancers, including cancer of the larynx, bladder, cervix, stomach, and colon. Leading an otherwise healthy lifestyle also reduces your cancer risk. That includes controlling your weight (be as lean as possible without becoming underweight); getting exercise (at least 30 minutes a day of physical activity), minimizing consumption of alcohol, and limiting consumption of foods high in fat or added sugars (because these contribute to weight gain), among others. It's believed that maintaining a healthy lifestyle reduces the incidence of cancer by 10 to 15 percent and mortality from cancer by 20 to 25 percent. Other important precautions include avoiding excessive exposure to the sun, which can cause skin cancer, including melanoma, which can be fatal. And stay out of tanning beds! According to the American Academy of Dermatology, people who use indoor tanning are 59 percent more likely to develop melanoma than those who have never done it. You should have an annual checkup with a physician and follow his or her recommendations for age-appropriate screening. You should also know your family history of cancer and share that with your physician. For example, a woman with a family history of breast cancer, especially certain kinds, has a higher risk of developing breast cancer herself. Regular screening is even more important in those cases. Both men and women should also check with their doctors to make sure they have been vaccinated for the human papillomavirus (HPV), which causes cervical and other cancers, and hepatitis B (HBV), the cause of most liver cancers. Not all cancers can be avoided, not by any means. But common-sense precautions can help significantly reduce your chances of developing cancer.