In the parts of the world governed by the Gregorian calendar, end-of-year reviews have made their way into managers' inboxes by now. Most look back at the significant events of 2015; some look forward and venture to predict what will happen in 2016.
In the scientific fields, these reviews invariably become impressive lists of accomplishments. And while it is not my intent to rain on their parade, I do believe that it is important not to get carried away by the festive holiday season. Especially in the field of human health, we should keep mankind's accomplishments in perspective so that we can better determine how scientific advancements will actually affect human health on a global scale.
The Battle Against Cancer: Fighting the Wrong Enemy
Year after year, media reports on progress in the diagnosis and treatment of cancer leave readers with the impression that the medical field is on a never-ending winning streak in the fight against the disease. But a look at overall statistics paints a less convincing picture. Although the number of deaths due to cancer is slowly declining in many high-income countries, it has replaced cardiovascular disease as the primary cause of death in these countries.
For our purposes, we can divide the complex family tree of cancers into two categories: carcinomas and non-carcinomas. Carcinomas are cancers originating within the cells that line the borders of the body's various organs, including the lungs, breasts, prostate and bowel. In adults, they make up at least 80 percent of all cancer cases, and they are typically more resistant to treatment. As a result, doctors often have to turn to a series of complex treatment schedules that rely on an extensive arsenal of medicines and procedures to address them.
The non-carcinoma cancers, on the other hand, form in the body's connective tissues, bones, muscles, blood, lymphatic tissue and nervous system. These cancers are less common and appear to be more straightforward, biologically speaking. They are also often more receptive to the type of "magic bullet" miracle treatment that we so often hear about in the press. For example, doctors have cleverly managed to weaponize the poliovirus against glioblastomas, a devastating type of brain cancer. The virus, which can penetrate neural cells, is used to hunt down cancerous cells hiding within the brain tissue. The experimental immunotherapy that was applied with spectacular success to a melanoma that had already spread to the brain of former U.S. President Jimmy Carter is yet another example of the medical field's trumpeted progress against this type of cancer. (The son of U.S. Vice President Joe Biden, however, recently lost his battle against brain cancer, inspiring U.S. President Barack Obama's latest "moon shot" to cure cancer — a program that will no doubt boost the scientific community's end-of-year reviews for years to come.)
But while the impact of these victories may indeed be spectacular for the individual patients they save, in terms of the population as a whole, they barely make a dent in total cancer statistics. (Remember, non-carcinomas make up only 20 percent of all cancer cases.) Therefore, developing countries with the ambition to acquire the skills and technology needed to replicate such cures for their own populations should carefully weigh whether the resources they are pouring into high-tech treatments are worth the relatively small impact they have on the population as a whole.
Re-Evaluating Our Strategy
If we hope to deal a significant blow to cancer, we need to make substantial progress in battling the more common carcinomas. Certainly, advances in diagnostic techniques have already allowed for earlier and earlier detection, ensuring that some 50 percent of cancer patients in high-income countries today survive their disease. Still, this might be a hollow victory, since recent statistical studies have shown that, against all expectations, cancer screening programs do not save more lives overall. The explanation for these findings could be that many early stage cancers may never have morphed into more invasive forms if left untreated. Furthermore, the harm that can be caused by unnecessary diagnostic tests and, in false positive cases, by treatments themselves may well offset the benefits of early intervention.
If we hope to deal a significant blow to cancer, we need to make substantial progress in battling the more common carcinomas.
And in the meantime, progress in treating more advanced forms of carcinomas remains painstakingly slow, largely because of their sheer complexity. However, there are some slivers of hope that progress can be made. For instance, further industrialization of genetic sequencing has enabled doctors to identify and track the cascade of mutations that increases the malignancy of tumors. This in turn allows for more precise treatment that is tailored to the individual carcinoma and the particular stage it is in. In addition, 2015 saw an explosion in the applications of the revolutionary CRISPR technique, a fast, easy and cheap method of identifying and editing DNA strips in chromosomes. The technique uses an enzyme combination that essentially performs a continuous search-and-replace function against a particular pattern in the genetic sequence. This allows doctors to probe DNA locations to discover how individual genes act and how silencing or activating the production of particular enzymes can boost the cells' own defenses or trigger suicide in the cancerous cells themselves.
Deciphering the complex pathways of cancer has never been easier, and more quick wins will undoubtedly emerge in the coming years. But I suspect that in the grand scheme of things, the sheer magnitude and difficulty of the cancer problem will continue to dwarf these feats, remarkable as they are, for decades to come.
Targeting Prevention Instead of a Cure
This is not to say that we should sit back and accept our fate. Like every biological phenomenon, cancer is the result of the interaction between the human genome and its environment. Though how much of the risk of cancer can be traced to genetic or environmental differences remains controversial, medical professionals strongly suspect that lifestyle choices play an important role. Studies have shown that when immigrants from developing countries with low cancer rates move to developed countries, their risk of developing cancer shoots up within a few generations as their families adopt a modern lifestyle. And just last year, a team at New York's Stony Brook University Cancer Center convincingly showed that environmental factors are the overwhelming driver of differences in cancer risk. (By comparison, the team concluded that only 10 percent of cancer cases have intrinsic genetic origins.)
On a global scale, the implications of these findings are enormous. As developing countries industrialize, they often import the Western lifestyle, bringing with it the same "diseases of affluence" that afflict populations in the developed world — including a majority of cancers. Take smoking, for instance. For decades, smoking has been known to cause about one-third of all deaths from cancer. But the sobering reality is that while smoking has leveled off in developed countries, tobacco consumption is still rising by more than 3 percent per year in the developing world. Will these regions take as long as the developed world did to curb the trend? What about the other unhealthy lifestyle choices that they are steadily importing from the West, which itself has hardly even begun to overcome the tremendous social inertia that allows such habits to persist?
Consider the case of India. With a population of 1.2 billion, India sees about 1 million new cancer cases diagnosed each year — about a quarter of Western Europe's incidence rate. But mortality rates from cancer are much higher in India, relative to the Continent, signaling a low rate of early detection and poor treatment outcomes. India has a relatively young population, and the number of new cancer cases it sees annually is expected to double over the next 20 years. Since doubling the country's health care services would not be a feasible response in even the best of economic times, New Delhi’s rising biotechnological proficiency and booming pharmaceutical industry will still probably be too little and come too late to counter the country's insidious cancer epidemic.
China has already given us a glimpse of what's to come, for India and for the developing world more broadly. In China, cancer is already the number one cause of death. The country accounts for 20 percent of the world's population but approximately 27 percent of cancer deaths worldwide. It has a high level of biotechnological prowess, gained from a flood of Ph.D. students returning home from the West's top universities, and its capability to take collective action on a grand scale is legendary. But these advantages will not be enough to enable China to keep up with its rising cancer rate, even as it rolls out additional infrastructure and services. Indeed, the Chinese collective mentality has, in some ways, proved to be a setback: Cancer is still considered taboo, even in modern Chinese culture, a social hurdle that may take too long to overcome in the face of China's rapid demographic aging. This problem is compounded by the explosive growth of Chinese economic infrastructure, which has had no patience for the idea of preventing pollution.
As developing countries look to replicate the successes of the developed world in their own cancer treatment centers, they should take a moment to consider whether they're setting their sights on the right target. It is only human to look at 2015's successes in cancer treatment and cheer on the world's wealthiest nation as it undertakes its self-proclaimed moon race to cure cancer. That said, while we can hope for miracles to bestow unto all the giant leaps of newly found health experienced by the lucky few, we should base our plans on the small steps that we can actually muster for the rest of mankind.