As cancer rates around the world increase, so must our efforts to combat this dreaded disease
A cancer diagnosis would shake anyone to the core. For most of us, the word itself is synonymous with doom. “There are many diseases that have awful prognoses,” says Murray Krahn, director of the Toronto Health Economics and Technology Assessment Collaborative, “but people fear breast cancer much more than they fear heart failure, even though heart failure carries a worse prognosis.” Why is this so? Perhaps because for generations we have viewed cancer as an irrevocable death sentence, with little chance of survival, much less of recovery. But for many of today’s cancer patients, that is no longer the case. Innovations born of necessity have enabled us to treat and, in some cases, cure the disease.
Nevertheless, cancer continues to be a leading cause of death worldwide, and its global burden is unmistakably rising. Close to 22 million new cases are expected to be diagnosed annually by 2030, according to the World Cancer Report 2014, published by the World Health Organization’s International Agency for Research on Cancer (IARC). This figure represents an increase of nearly 90 percent over the estimated 14.1 million new cases diagnosed worldwide in 2012. In that year, lung, colorectum, prostate, stomach and liver were the five most commonly diagnosed sites among men, while breast, colorectum, cervix, lung and the uterus were the most commonly diagnosed sites among women. “Predominantly, this [increase] has been driven by the growth and aging of populations,” says Christopher Wild, director of the IARC and an editor of the report. “Cancer is a disease of aging. As people are living longer and not dying of infectious diseases, the cancer numbers are going up.”
Wild was particularly surprised by the prevalence of breast cancer among women from countries with a wide range of incomes. “One in five of all people living, worldwide, within five years of a cancer diagnosis are breast cancer survivors,” he relates.
All of the news, however, is not bad. Paolo Vineis, chair of Environmental Epidemiology at Imperial College London, highlights some of the achievements made in the war on cancer. In most high-income countries, “mortality is going down, largely due to the fact that the frequency of smoking has decreased in men, so many tobacco-related cancers have been prevented.” Vineis notes that this decreased mortality is accompanied by an increased incidence, reflecting the effectiveness of new therapies and techniques that enable earlier diagnosis. The growing arsenal of targeted cancer treatments promises even better outcomes ahead.
Infection-related cancers still constitute up to 16 percent of the disease worldwide, with a higher proportion in low-income countries, particularly in sub-Saharan Africa, where the figure is 33 percent. Helicobacter pylori, Hepatitis B or C, and human papillomavirus infections are causally associated with the development of cancer.
Although some infections can be difficult to avoid, much of the increase in the global cancer burden is expected to come from lifestyle-associated cancers in low- and middle-income countries. The use of tobacco, consumption of alcohol and highly processed foods, obesity and lack of physical activity are all risk factors, and are all on the rise in many populations. Max Parkin, an epidemiologist at the University of Oxford, found that known lifestyle and other environmental factors accounted for 40–45 percent of all cancers in the UK in 2010.1 In light of these and other findings, both Vineis and Wild stress that prevention is key to decreasing the number of people diagnosed with cancer each year. “We cannot hope to treat our way out of the cancer problem,” says Wild.
Some of the most important insights into the molecular basis of cancer have come from families and groups of people with genetic predispositions to the disease. Numerous genome-wide association studies have sought to identify additional genetic loci that contribute to tumorigenesis. According to Kari Hemminki, a professor at the German Cancer Research Center in Heidelberg, over 300 low-risk loci have been identified in this manner, but “there is a lot of uncertainty about their cumulative risk.” Studies to look for genes that confer susceptibility to particular environmental agents have also been “largely disappointing,” he says. “One can more or less predict the risks by looking at the environmental and genetic effects [independently].”
Many gaps remain in our epidemiological understanding of cancer. “There are some cancers for which we still have almost no clue about the major causes of the disease, including prostate, pancreas, brain and kidney,” says Wild. Environmental and lifestyle factors and single-gene mutations might contribute little to overall risk in these cancers, or we simply might not have found the specific culprits.
What’s It Worth?
Given the number of individuals who are diagnosed with cancer each year, it is no surprise that the pharmaceutical industry has invested a substantial portion of its time and money in developing drugs to treat and cure the illness. Unfortunately, “so many of these [currently used] drugs fail to really provide durable survival,” says Christian Rommel, vice president of oncology research at Amgen, in Thousand Oaks, California. But Rommel is optimistic about the possibilities offered by two new approaches in drug development: therapies directed against specific targets known to be altered in cancerous cells, and immunotherapies, which re-activate the immune system to attack the tumor. Combining drugs from these two classes could provide the kind of durable survival he seeks to achieve.
In general, spending money to treat cancer means that more people survive it, at least within a given period after diagnosis. In a much-cited paper, Kevin Murphy and Robert Topel of the University of Chicago Booth School of Business concluded that a 1 percent decrease in mortality from cancer would be worth about $500 billion to the US economy.2 As the United States invested about $50 billion in medical research in total, of which 40 percent was publicly funded, they argued that investing in medical research was, indeed, worth it.
With cancer incidence on the rise, new therapies will be essential to curbing its effects. “The reason we treat illness is not to save money; we treat illness because we want to improve health,” says Krahn. He argues that although cost is important, new treatments should be judged first and foremost on their therapeutic potential. Rommel agrees: “Every meaningful therapy that provides durable overall survival—or at some point, let’s hope, cure—will justify the investment.” Already, advanced treatments are making cancer a less scary word.
1. Parkin, D.M. Brit. J. Can. (2011). doi:10.1038/bjc.2011.474.
2. Murphy, K.M. & Topel, R.H. J. Political Econ. 114, 871–904 (2006).
Illustrations by Veronica Lawlor
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