Preventing cancer – a global health challenge?

A few weeks ago, the Biden Cancer Moonshot announced actions to expand access to cancer screenings, prevent more cancers before they start, and drive new innovation to deliver the latest therapeutics and technologies to patients, families and communities across America. Data from the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) shows that a majority of countries around the world do not adequently finance and prioritize cancer care. A significant part of these initiatives must be cancer prevention and early detection. While steady strides have been made towards incorporating prevention into the global cancer agenda, the road forward is long and challenging. Some facts are clearer than others. Cancer is a multi-step process that often takes decades to develop and this in itself could be exploited as a window of opportunity to prevent the disease. Research suggests that behavioral or lifestyle changes such as adopting healthy eating habits, engaging in physical activities, getting vaccinated against particular viruses and ceasing tobacco smoking can prevent certain types of cancers. The challenge all along has been to turn this knowledge into global health action.

Consuming fruits and vegetables is protective against many cancers in large cohort studies (1,2). Nevertheless, global fruit and vegetable consumption data suggests that low and middle-income countries show the least intakes, likely related to availability and affordability. In the past few decades, there seems to have been an obvious shift in dietary patterns, especially in parts of the world like Latin America where diets have gone from high-cereal and high-legume to high-meat and high-sugar (3). Interestingly, in Brazil, imposing a higher tax on sugar-sweetened beverages resulted in the ultimate decline of their sales (4), indicating that economic practices can directly affect public health outcomes. Higher levels of physical activity are associated with better cancer outcomes (5, 6) and there have been multiple efforts to recognize this at the policy recommendation level as well as the community level in some countries. We are yet to see low and middle-income nations actively embrace these changes and make them a public health priority.

Vaccination, when it is possible, is probably one of the most effective cancer prevention strategies for several cancers caused by viruses (7). In the future, we will likely observe more drastic drops in the rates of liver cancer in certain regions by the implementation of successful hepatitis B vaccination programs (8). Yet, there are many cancer-causing viruses that don’t have vaccines. Although a good vaccine exists against the most common cervical cancer-causing human papillomaviruses, it is currently caught up in a large political debate in many countries, including the US. In the midst of it all, cervical cancer continues to be one of the most prevalent cancers amongst women, globally. Effective tobacco control in many regions of the world has consisted of regulating the tobacco industry itself. Although cigarette sales have been declining in the United States over the past few decades, the worldwide trend in low and middle-income countries is different. With alarming rates of cigarette smoking recorded from countries like China, Indonesia and the Pacific islands, the global landscape of certain cancers will likely be altered and will present a significant challenge to global public health.

Attempting to target a disease that has not even occurred in the first place often works against the success of cancer prevention. A better approach might be to think of cancer in terms of identifying and reducing risk. Even though the existing cancer prevention strategies cannot guarantee that a given individual will not develop cancer, evidence strongly suggests that the risk of cancer could be significantly reduced. With advances made in the field of cancer research, we would like to think that we have identified many of the risk factors of different cancers, but we are far from it. Not only do we need to control risk factors that we currently have a plethora of evidence for but we also need to identify new ones. Novel chemicals are continuously synthesized and with relatively lax regulatory requirements, especially within low and middle-income nations, necessary long-term carcinogenicity safety assessments may not be conducted. The connections between other non-communicable diseases (eg. diabetes, obesity) and cancer are being slowly unraveled. Immunity and other defense systems of the body also play a major role in preventing certain cancers from developing (9). Research that investigates the etiologies of cancer as well as accurate methods to predict it, is therefore as important as research that studies cancer treatment. With recent developments made in the field of cancer data and artificial intelligence (AI), better technologies and methodologies for cancer prevention and care will likely emerge. These resources must be accessible and affordable for diverse populations if they were to truly address cancer health disparities around the world.

We need to recognize that cancer prevention, in many cases, is financially less cumbersome than treatment. Yet, for many low-income countries, cancer prevention is more of a luxury than a priority. Therefore, new and cheaper ways of incorporating cancer prevention into the lives of the most economically disadvantaged individuals need to be designed and implemented. In any case, for the general public, anywhere in the world, it’s often a question of how convenient it is to embrace a given intervention. At the end of the day, the reality is that prevention needs to be easy, in order for it to work. Whether it’s eating a broccoli salad for lunch or participating in a government-sponsored community aerobics class, cancer prevention strategies have to be derived from evidence-based science but eventually made “user-friendly”.