The Epidemiology of Prostate Cancer
Globally, lung cancer is the most frequent malignancy in men followed by prostate cancer. In 2018, GLOBOCAN estimates that there were 1,276,106 new cases of prostate cancer worldwide with 358,989 recorded deaths from the disease (Bray et al., 2018). The incidence of prostate cancer rises with age, and rates differs across populations and regions (Ferlay et al., 2018). Ferlay et al. reported in 2018 an age standardized rate of 79.1 per 100,000 people for Oceania followed closely by 73.7 per 100,000 people for North America and 62.1 per 100,000 people for Europe (Ferlay et al., 2018). The disease is more frequently diagnosed among older men and worldwide the mean age is 66 years (Perdana et al., 2016; Panigrahi et al., 2019). It is reported that approximately 1 in 350 men below the age of 50 years will be diagnosed with the disease while in those within the 50 - 59 age group, the incidence rate increases to 1 in 50 men, and those over 65 years, 3 in 5 men (Perdana et al., 2016). Notably the incidence rate differs among ethnic groups with the highest observed in African American men with 157.6 per 100,000 people compared with 93.9 per 100,000 in Caucasian men (SEER Cancer Statistics Review, 2016). The differences in incidence rates could be attributed to genetic makeup, environmental factors which influences the etiology of the disease and variances in screening methods involving prostate specific antigen (PSA) testing as well as inequalities in healthcare access (Chu et al., 2011).
The well known risk factors of prostate cancer are family history, advancer age over 65 years old, ethnicity, genetic factors and other associated factors such as unbalanced diet, obesity, physical inactivity, infections, inflammation, and environmental contact with ionizing radiation or cancer-causing chemicals (Wilson et al., 2012; Markozannes et al., 2016). Approximately 20% of prostate cancer patients indicated a family history and hereditary genetic background is concomitant with elevated risk for the disease, with a contribution of approximately 5% (Gallagher et al., 1998; Sridhar et al., 2010). Dietary factors may have a crucial role in the progression of prostate cancer. Studies have reported a positive association between fat and dairy products, and prostate cancer mortality (Armstrong et al., 1975). A review of epidemiological and experimental studies showed that diets rich in saturated animal fat are associated with increased growth of prostate cancer cells due to higher levels of androgens (Vankateswaran and Klot, 2010). On the converse, Brassica vegetables have shown evidence for a protective effect against prostate cancer, and decreased risk have been observed with consumption of green tea and soy (Joseph et al., 2004; Fujiki et al., 1998).
The epidemiology of prostate cancer has been transformed due to the identification of biomarkers such as prostate specific antigen that are positively associated with the diagnosis of prostate cancer (Filella et al., 2018). Furthermore, there is increased survival among prostate cancer patients due to effective treatments, improved supportive care and advances in cancer detection. However, there are disease-specific and treatment-related side-effects which may negatively impact the health-related quality of life and well-being of prostate cancer patients (Lin et al., 2009).