Epidemiological data consistently show sustained upward trend in the incidence of cancer. The International Agency for Research on Cancer (IARC) estimated that in 2018 more than 18 million people were diagnosed with cancer, and in about 9.6 million cases cancer could be the cause of death. At the same time, an increasing percentage of overweight and obesity is observed in both adults and children. According to the World Health Organization (WHO), in 2016 over 1.9 billion (39% of the population) of adults were overweight, of which over 650 million (13%) were obese. Obesity is closely related to the risk of cancer development. Excessive body weight is considered as a second risk factor for the development of specific cancers after smoking. According to IARC data, high BMI index may be the cause of up to half a million cancer cases per year. In addition, overweight and obesity contribute to increased mortality due to malignancies - it is estimated that they are the cause of death in 20% of women and in 14% of men. Data from the American Cancer Society indicate increased mortality due to pancreatic cancer, liver cancer, multiple myeloma, and Hodgkin's lymphoma in connection with the occurrence of excessive body weight. The study tried to confirm the influence of obesity on the risk of cancer. To achieve this, risk factors such as excessive adipose tissue, chronic inflammation, hyperinsulinaemia and hyperglycaemia, sex steroids, and microbiome were taken into account. In addition, the study presents a simple method of estimating the risk quotient of chances of developing malignant tumors in people with excessive body mass and methods of cancer disease prevention. According to the current state of knowledge, the modification of factors significantly affecting the risk of falling ill may contribute to reducing the risk of cancer. In view of the above, the importance of the problem of overweight and obesity in society and their impact on the occurrence of some types of cancer should be emphasized. Thus, the understanding of excessive body weight as a serious health and social problem sets one of the priorities in the area of public health.
Keywords: cancer; excessive body weight; obesity; risk factors.