Precision medicine holds great promise for managing and treating cancer. Yet an underfunded and underutilized breakthrough is already available: cancer prevention.
An ounce of prevention is worth a pound of cure, as the saying goes. This may be particularly salient for cancer, a multi-faceted disease that has evaded durable successes in treatment compared to other noncommunicable diseases. Survival rates vary drastically by sex, race and cancer type. For example, 99% of white men diagnosed with prostate cancer will survive five years after diagnosis compared to 96% of black men whereas only 15.2% of men who develop lung cancer will survive five years compared to 21.3% of women.
In addition to the physical and emotional costs associated with severely compromised quality of life and shortened life expectancy, there are steep economic costs. Cancer patients and their families, employers, insurance companies and Medicare and Medicaid reportedly spent about $87.8 billion on cancer-related health care in 2014. Three short years later, investment in National Cancer Institute (NCI) sponsored cancer research has topped $5.389 billion. Cancer prevention research receives a relatively microscopic slice of the NCI funding pie of just 6.9%. Perhaps not surprisingly, this “micro-ounce” of investment has not translated into large-scale cancer prevention.
Three short years later, investment in National Cancer Institute (NCI) sponsored cancer research has topped $5.389 billion. Cancer prevention research receives a relatively microscopic slice of the NCI funding pie of just 6.9%.
According to the WHO, 30-50% of cancer cases are preventable. In other words, up to half of all cancer cases could be avoided by targeting certain modifiable risk factors broadly classified as diet and exercise, alcohol consumption, infections, occupational exposures, radiation, environmental pollution and tobacco. While genetics determines in part both cancer risk and prognosis, and perhaps one day can be precisely targeted to cure cancer, population-level prevention strategies will still likely have a greater impact on overall health both in the U.S. and globally.
Cancer prevention strategies built around behaviors include wearing sunscreen, eating a healthy diet, drinking alcohol in moderation, being physically active and maintaining a healthy weight, quitting smoking or better yet never starting, getting vaccinated against HPV and HBV, wearing protective gear to prevent occupational exposure to carcinogens, using chemopreventive agents in high-risk populations, and undergoing regular screening.
Implementing these cancer prevention strategies is challenging for many reasons. First, it may not even be an option: upstream factors such as education, food subsidy policies, accessibility and safety of the built environment, and social acceptability can constrain choice. Second, miscommunication of good science and repetition of flawed science and fringe views creates confusion that undermines the evidence base and clarity of public health messaging. Third, behavioral change itself is difficult as it requires the knowledge, capacity, motivation and support to change. Fourth, the returns on cancer prevention are less palpable than cures, as it is measured in terms of statistical cases or deaths avoided.
Quitting smoking is a prime of example of the challenges of cancer prevention despite the fact that smoking is linked to about 90% of all lung cancer cases. Arguably, tobacco control has been somewhat successful in the US. Smoking prevalence peaked in the mid-1960s when approximately half of all men and a third of all women smoked. Over the course of 50 years, smoking prevalence has declined by more than 60%. This remarkable drop began shortly after the 1964 U.S. Surgeon General’s report on smoking and health and continued with advertisement bans, cigarette taxes and warning labels, prescription and over-the-counter smoking cessation aids, and crucial litigation to recover health care costs associated with tobacco-related illnesses and impose restrictions on cigarette sales and marketing.
What is the lesson for the rest of the world? Effective and affordable treatment for lung cancer is elusive, and thus cancer prevention is the breakthrough.
Notably absent are effective strategies to change individual-level behaviors. Nearly seven out of every ten U.S. adults reported in 2015 that they wanted to quit smoking completely. But many quitters will start smoking again due to nicotine withdrawal symptoms, stress and weight gain. Recently, electronic cigarettes (e-cigarettes) have been proposed as a smoking cessation aid but the long-term health consequences and potential “gateway” to tobacco smoking in adolescents remains controversial. There is also a shift towards community-based participatory interventions—with an emphasis on minority communities where smoking prevalence is much higher —to tailor smoking cessation programs and results have been encouraging.
What is the lesson for the U.S.? Smoking prevalence still remains unacceptably high. There needs to be additional investment in studying and implementing cancer prevention interventions, with a special focus on identifying effective ways to stimulate prolonged behavioral changes in vulnerable populations in order to reduce smoking-related health disparities and prevent adolescents from starting smoking.
What is the lesson for the rest of the world? Effective and affordable treatment for lung cancer is elusive, and thus cancer prevention is the breakthrough. Smoking prevalence is increasing in many regions of the world, and 80% of tobacco-attributable deaths are already occurring in low- to middle-income countries (LMICs). Based on the U.S. experience, we know exactly what is coming: a surge in lung cancer incidence and mortality (along with other tobacco-related illnesses). But additional challenges in LMICs include resource constraints, unfettered cigarette advertising and aggressive market expansion, lack of regulation, the politics of government-owned tobacco companies in some countries, social inequities, the interplay with chronic air pollution and the rise of “Western lifestyle” risk factors like inactivity and obesity.
The bottom line is that we must invest more than a “micro-ounce” in cancer prevention to effectively combat this deadly noncommunicable disease on a global scale. We need to invest more in tailoring programs according to critical contextual factors to improve their success. When it comes to lung cancer prevention specifically, we need to find effective ways to help people stop smoking. And we need to ensure that future generations never, never, never start.