Dr. Kalil: Obesity and smoking are factors in the development of tumors
Obesity and a sedentary lifestyle are among the main modifiable risk factors for the development of cancer, second only to smoking. Speaking to CNN Vital Signs, experts warn that excess body fat triggers a series of biological mechanisms that favor the emergence of tumors, including insulin resistance, changes in hormonal metabolism and, above all, a process of chronic inflammation in the body.
According to Paulo Hoff, professor of Oncology at FMUSP and director of ICESP, obesity can increase the risk of liver cancer by two to four times.
"We are talking about a 200% to 400% increase in the risk of liver cancer," said the professor.
He highlighted that, disregarding tobacco and excessive alcohol consumption, "obesity ends up being one of the factors that increases the risk of developing cancer", reinforcing the need for good nutrition, physical exercise and control of body weight.
Sedentary lifestyle and tumor recurrence
The impact of a sedentary lifestyle was also highlighted in the debate. Paulo Hoff cited a prospective Canadian study presented in 2025, according to which patients who received monitoring for physical activity had half the recurrence of tumors compared to those who received only general guidance.
"There was a 50% drop in recurrence compared to the group that was well treated but did not exercise regularly," he explained.
In addition, the study recorded a reduction in the emergence of new tumors, such as breast cancer among participating women, demonstrating that the impact of physical activity transcends the treatment of already diagnosed cancer.
Maria Ignez Braghiroli, clinical oncologist at ICESP, added, mentioning another work presented at the American Oncology Congress, which analyzed dietary patterns and their correlation with inflammatory factors measured in the blood.
"In that group of people who had a diet with a less inflammatory profile, there was also less recurrence of cancer, especially if associated with physical activity", highlighted the oncologist.
Cigarette smoking and tumors other than the lung
Smoking remains the main risk factor for cancer in the world. In Brazil, the smoking rate has declined and is around 12%, but globally, lung cancer caused by cigarettes continues to be the main cause of death related to the disease.
Braghiroli drew attention to an often neglected aspect: the effects of cigarettes on other organs.
"Pancreatic cancer is one of the main risk factors for smoking, bladder cancer is one of the main risk factors for smoking", warned the specialist, highlighting that these are diseases that people generally do not associate with smoking, but which also have their risk increased by the habit of smoking.
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Source: CNN