1 in 4 Brazilians unaware cancer is preventable, study finds

A quarter of Brazilians do not believe cancer can be prevented. This finding, released Wednesday from a national survey called "More Data, Better Health," cuts to the heart of a public health crisis unfolding in real time. The country is bracing for 781,000 new cancer diagnoses each year through 2028—a jump of nearly 11 percent from the previous three-year period. Yet the knowledge gap persists: one in four people remain unaware that the disease is largely avoidable.

The research, conducted by Umane and Vital Strategies with support from Instituto Devive and technical partnership from Brazil's National Cancer Institute, surveyed 6,500 people across every state and the federal district. It mapped what Brazilians understand about the habits and behaviors that drive cancer risk: smoking, alcohol, diet, weight, physical activity. The results reveal a landscape of awareness that is deeply uneven.

Smoking awareness dominates the conversation. Nine in ten respondents—90.5 percent—know that cigarettes cause cancer. Genetic inheritance and excessive sun exposure follow close behind, recognized by 89.4 and 88.3 percent respectively. These are the victories of decades of public campaigns, regulatory restrictions, and sustained messaging. Smoking has become the textbook example of what sustained prevention work can achieve.

But step away from smoking and the picture fractures. Less than half of Brazilians—48.3 percent—recognize that a sedentary lifestyle increases cancer risk. Only 54.1 percent link obesity and overweight to the disease. The connection between what people eat and whether they develop cancer remains poorly understood. Ultraprocessed foods like instant noodles, packaged snacks, and industrial ice cream are identified as cancer risk by 65.6 percent of respondents. Processed meats like ham and sausage reach 70.7 percent. But red meat? Only 27.5 percent of Brazilians believe that eating it frequently raises their cancer risk—a stunning gap given the scientific evidence.

Young adults aged 24 and under are consuming these high-risk foods at the highest rates, and crucially, they show no intention of stopping. Nearly half—49.1 percent—eat red meat regularly without planning to reduce it. A third consume ultraprocessed foods the same way. Twenty-four percent drink sweetened beverages without intent to change. Among the youngest drinkers, 16.9 percent consume alcohol and have no plans to cut back. They are, in effect, living out the knowledge gap in real time.

Another blind spot emerged around breastfeeding. Four in ten respondents did not know that nursing protects women against breast cancer. This protective factor, well-established in medical literature, remains invisible to a significant portion of the population.

Experts involved in the study point to a straightforward explanation: awareness follows investment. Smoking received decades of educational campaigns, regulatory action, and political will. The other risk factors—the ones embedded in daily life, in food systems, in urban design, in economic access—have received far less attention. The gap in knowledge is not accidental. It reflects where resources have been directed and where they have not.

But information alone will not solve this. The researchers emphasize that income, access to healthy food, safe spaces for physical activity, and public health policies that actively encourage wellness all shape what people can actually choose. A person living in a neighborhood without parks faces different constraints than one with access to green space. A family with limited income faces different food options than one with resources. Prevention, in other words, is not simply a matter of knowing better. It is a matter of being able to do better.

The findings are now being used to design new communication and prevention strategies focused on the factors Brazilians understand least. The work ahead is to close the gap—not just in what people know, but in what they can actually do.