I was watching one of the 24-hour news stations last night (no, not that one) and saw a breast cancer activist wondering why we don’t devote resources to an all-out fight to cure breast cancer as we did with polio, leading to its eradication in the US. I often hear questions like this: if we can (send a man to the moon, wipe out polio, etc) then why can’t we cure cancer?
It’s a good question, in context. When one of the diseases you care most about is still out there, while others are on the wane, it can add to fear and to frustration. I don’t wish to minimize the political choices behind research funding, but there are good biological explanations for why some diseases are “wiped out” while others still plague us.
Illnesses are caused by a variety of problems, some internal, some external, some unknown. In the history of medicine and public health, we’ve only been able to eradicate a single human disease. Smallpox was ideal in this sense. Humans are the only natural host, and transmission was usually from person to person—there was no reservoir for the disease other than people. In theory, then, all it would take is immunization of most humans to eradicate the disease in nature, and that’s what was done. Near the end of the pandemic, teams would travel to outbreaks vaccinating the people within the outbreak area, and in surrounding areas to contain the spread. This way there was less need to re-vaccinate entire populations.
Polio is a little more difficult. It only infects humans but the virus is transmitted though fecal contamination of water and sometimes from person to person via oral secretions. One infected person and a poor water treatment system can lead to continued spread. This meant that to eradicate polio in the US, a massive vaccination program was needed, one which began with the development of polio vaccines after WWII and essentially ended in the late 1970s when polio was no longer transmitted in the US. As Maryn McKenna documents in Beating Back the Devil, the eradication campaign had a rocky start, with an early batch problem leading to transmission of polio in some areas. The fact that millions still clamored for the vaccine shows how much polio was (rightly) feared. The eventual success of vaccination saved millions from paralysis, illness, and fear. In parts of the world where natural, economic, and military disasters are most prevalent, polio is still a problem.
Polio is a simple disease—one virus, one host, an effective vaccine—and still it’s out there (although not in the US). Cancer is so much more. The term “breast cancer” refers to many different diseases, all of which cause abnormal growth of breast cells. The fight against breast cancer requires improved prevention, early detection, and treatment of the disease at all stages. And we have been improving, with death rates from many cancers decreasing. But the disease(s) have many causes, some of which are not amenable to change. You cannot change a family history of breast cancer. Unlike lung cancer, there aren’t a lot of strong environmental risks (such as cigarette smoking) that can be modified. We are largely stuck with early detection and good treatment. Breast cancers caught early can often lead to surgical cure, but our screening methods are imperfect and likely always will be. There is no perfect test that finds all breast cancers but also avoids erroneous diagnoses that lead to unnecessary tests and treatments. And there is no guarantee that a cancer found early will be cured—only probabilities.
Perhaps thinking of the “fight against cancer” as a win-lose battle is not all that productive. Human health and disease is complex and there are rarely simple answers. The simplest answers—improving economic and social justice—are often the hardest to achieve. But that doesn’t mean we can’t try.