Some of these unanswered questions (or PQs, as the Cancer Institute has catchily dubbed them) are old, neglected mysteries. Others are based on newer observations. And some are questions that we haven't had the technology to address in the past, but that seem more attainable today.
Eight of the most provocative questions are below, rephrased by me but numbered so you can find their original language if you'd like. All 24 original questions are here. (The NCI wants to be clear that their numbering system is strictly random, presumably so they don't receive eight thousand grant proposals for PQ 1.)
Why are patients with diseases such as Alzheimer's, Parkinson's or Huntington's significantly less likely to get cancer? (PQ 6)
The reverse is also true: People who have survived cancer have a lower risk of developing these neurological disorders. It's unusual to study anti-correlations rather than correlations--usually we want to know what makes us more likely to be sick. But teasing out the molecular and cellular mechanisms that prevent cancer patients from developing Alzheimer's, and vice versa, would teach us a lot about cancer--and about these other illnesses.
How are obesity and cancer connected? (PQ 1)
Obese individuals have a greater risk of many types of cancer. But scientists don't know what, specifically, connects cancer and obesity. It's also unclear whether losing weight lowers a person's risk of cancer. Once someone becomes obese, has the carcinogenic switch already been flipped? Are some risks reversible?
What does an animal's lifespan have to do with cancer? (PQ 7)
In humans, most cancers are diseases of aging. Young people with cancer are a relative rarity; as we use up more of our 80 or so years, our cancer risk rises. In animals that are susceptible to cancer, their disease looks similar to ours. But their lifespans can be radically different. Mice only live about 2 years, yet we can easily model cancers in them. Dogs can develop cancer within their 15 or 20 years of life.
Not all animals have a cancer problem, though. Sea turtles can live for at least as long as humans, if not decades longer, and seem to almost never get cancer. We clearly have a lot to learn about how animals, including humans, age. We also have yet to elucidate the ways in which cancer is, and is not, a disease of aging.
How many cancers are caused by viruses? (PQ 12)
The discovery that viruses caused most cervical cancers led to the development of an HPV vaccine. Some other cancers are known to be linked to viral or bacterial infections. By finding out which types of cancers come from catchable agents, we can learn more about how tumors form and might even be able to create new cancer vaccines.
Why do some types of cancer cluster in geographic regions? (PQ 2)
Your risk for some cancers varies depending on where you live--and if you move, your risk will change. Which of these cancers are being caused by a toxin or other environmental factor? Which are caused by cultural factors such as diet?
Can we find extra-tiny tumors? (PQ 13)
Current imaging technology already has a pretty impressive resolution; doctors can spot tumors that are just one cubic millimeter in size. But could improved technologies reveal tumors that were orders of magnitude smaller? What about a single tumorous cell?
Why do cancer survivors have a higher risk of developing a second cancer? (PQ 15)
Some of a former cancer patient's risk might have to do with the chemotherapy and radiation she or he has already undergone. But if there's more to the story, it might reveal underlying factors that put a person at risk for all cancers--not just cancer of the stomach or skin or prostate.
Could we quantify a person's cancer risk? (PQ 3)
Perhaps in the future, a tool or test in the doctor's office could analyze a blood sample and report back on your current risk of developing cancer, based on carcinogens or metabolic products in your body. Or we could keep sensors in our homes--or wear them on our bodies--that measure our cumulative exposure to carcinogens. What if everyone wore a cancer watch that counted down their healthy days? (You're free to use that idea for a dystopian science-fiction novel. But please send me a copy.)