Introduction
Cancer is known as one of the leading causes of death in the world (
1). In 2020, 19.3 million new cases of cancer and approximately 10 million cancer deaths occurred worldwide (
2). In addition to early mortality, cancer is associated with disability in affected patients and imposes a high economic burden on the health care system (
3). Therefore, finding approaches to prevent cancer and cancer-related mortality is necessary.
It is well known that genetic and environmental factors such as smoking, low physical activity, and unhealthy diet are involved in cancer etiology. Previous studies have shown that several dietary factors have a potential role in cancer incidence and mortality (
4). For instance, higher intake of red and processed meats was associated with an increased risk of cancer and cancer-related mortality (
5), while higher consumption of fruits and vegetables was associated with a reduction in cancer incidence (
6), and mortality (
7). In recent decades, the intake of sweetened beverages, including sugar-sweetened beverages (SSBs) and fruit juices, and their associations with cancer received much attention. SSB consumption has increased worldwide, especially among adolescents (
8). SSBs are beverages containing caloric sweeteners (sucrose, fructose, etc.), which include carbonated drinks, soft drinks, and fruit drinks.
There is considerable evidence linking excessive consumption of SSBs to a wide range of health problems. Several studies have shown that consumption of SSBs was associated with a higher risk of type 2 diabetes mellitus (
9), hypertension, cardiometabolic diseases (
10,
11), non-alcoholic fatty liver disease (
12), and inflammatory disorders (
13–15). The positive association between SSBs and obesity risk has also been reported (
16,
17). In terms of cancer, it has been shown that SSBs might affect cancer risk through chronic inflammation and hormonal imbalance (
18–20). There might also be an indirect association between SSBs and cancer risk through obesity. Furthermore, SSBs consumption is associated with glycemic response, hyperinsulinemia, and higher levels of circulating insulin-like growth factor-I (IGF-I), which might be associated with cancer progression (
21,
22) (
Figure 1). Despite the mentioned evidence, findings from epidemiological studies on the association between the consumption of sweetened beverages and the risk of cancer and its mortality are controversial. In this review, we aimed to summarize the epidemiological evidence on the associations of sweetened beverages in different types with cancer incidence/mortality in adults and also discuss the controversial findings in this regard.