Question

DISCUSS WHY THE INCIDENCE OF PROSTATE CANCER TURNS TO BE HIGHER AMONG THE AFRICAN AMERICANS MEN THAN THE OTHER ETHNICITY, AND INCLUDE STATEMENTS OF THE PROBLEMS

Answer 1

Prostate cancer is the second most frequent cancer diagnosis made in men and the fifth leading cause of death worldwide. Prostate cancer may be asymptomatic at the early stage and often has an indolent course that may require only active surveillance. Based on GLOBOCAN 2018 estimates, 1,276,106 new cases of prostate cancer were reported worldwide in 2018, with higher prevalence in the developed countries. Differences in the incidence rates worldwide reflect differences in the use of diagnostic testing. Prostate cancer incidence and mortality rates are strongly related to the age with the highest incidence being seen in elderly men (> 65 years of age). African-American men have the highest incidence rates and more aggressive type of prostate cancer compared to White men. There is no evidence yet on how to prevent prostate cancer; however, it is possible to lower the risk by limiting high-fat foods, increasing the intake of vegetables and fruits and performing more exercise. Screening is highly recommended at age 45 for men with familial history and African-American men. Up-to-date statistics on prostate cancer occurrence and outcomes along with a better understanding of the etiology and causative risk factors are essential for the primary prevention

Introduction

Prostate cancer is the second most frequent malignancy (after lung cancer) in men worldwide, counting 1,276,106 new cases and causing 358,989 deaths (3.8% of all deaths caused by cancer in men) in 2018 [1, 2]. The incidence and mortality of prostate cancer worldwide correlate with increasing age with the average age at the time of diagnosis being 66 years. Of note, for African-American men, the incidence rates are higher when compared to the White men, with 158.3 new cases diagnosed per 100,000 men and their mortality is approximately twice as White men [3]. Reasons for this disparity have been hypothesized to differences in social, environmental and genetic factors. Although 2,293,818 new cases are estimated until 2040, a small variation in mortality will be observed (an increase of 1.05%)

Prostate cancer may be asymptomatic at the early stage and often has an indolent course, and may require minimal or even no treatment. However, the most frequent complaint is difficulty with urination, increased frequency, and nocturia, all symptoms that may also arise from prostatic hypertrophy. More advanced stage of the disease may present with urinary retention and back pain, as axis skeleton is the most common site of bony metastatic disease.

Many prostate cancers are detected on the basis of elevated plasmatic levels of prostate-specific antigen (PSA > 4 ng/mL), a glycoprotein normally expressed by prostate tissue. However, because men without cancer have also been found with elevated PSA, a tissue biopsy is the standard of care to confirm cancer’s presence.

Diet and physical activity play an important role in prostate cancer development and progression. Dietary factors are mainly associated with the observed worldwide and ethnic differences in the incidence rates of prostate cancer

Most studies are devoted not only into identifying genes involved in the inherited form of prostate cancer but also the mutations occurring in the acquired form. Therefore, a detailed analysis of prostate cancer epidemiology and evaluation of risk factors can help to understand the connection between genetic mutations and the role of the environment in triggering these mutations and/or favoring tumor progression. Increased understanding of the etiology and causative risk factors of prostate cancer will provide ways to identify at-risk males and support the development of effective screening and prevention methods.

Epidemiology

Based on GLOBOCAN 2018 estimates, we have evaluated worldwide prostate cancer incidence and mortality rates, as well as analyzed incidence and mortality, temporal trends and survival rates.

Incidence

The incidence rate of prostate cancer varies across the regions and populations (Fig. 1) [2]. In 2018, 1,276,106 new cases of prostate cancer were registered worldwide, representing 7.1% of all cancers in men [1]. Prostate cancer incidence rates are highly variable worldwide. The age-standardized rate (ASR) was highest in Oceania (79.1 per 100,000 people) and North America (73.7), followed by Europe (62.1). Conversely, Africa and Asia have incidence rates that are lower than those from developed countries (26.6 and 11.5, respectively) [2]. Differences in incidence rates were 190-fold between the populations at the highest rate (France, Guadeloupe, 189.1), and the populations with the lowest rate (Bhutan, 1.0).

Map showing estimated age-standardized incidence rates for prostate cancer worldwide in 2018, in males including all ages. Created with mapchart.net. Data obtained from Globocan 2018 [2].

Prostate cancer incidence increases with age [2]. Although only 1 in 350 men under the age of 50 years will be diagnosed with prostate cancer [10], the incidence rate increases up to 1 in every 52 men for ages 50 to 59 years. The incidence rate is nearly 60% in men over the age of 65 years

The reason for these differences among the countries is not entirely clear. The worldwide variations in prostate cancer incidence might be attributed to PSA testing [12]. For example, in Europe, prostate cancer is the most frequently diagnosed cancer among men, accounting for 24% of all new cancers in 2018, with around 450,000 new prostate cancer cases estimated in 2018 [13]. While in the USA, prostate cancer is the second most common cancer accounting for 9.5% of all new cancer cases (164,690 new cases of prostate cancer) registered in 2018 [14]. According to recently conducted research studies, around 20-40% of the prostate cancer cases in the USA and Europe could be due to overdiagnosis through extensive PSA testing

Research has shown that African-American men have the highest incidence of prostate cancer worldwide and more likely to develop disease earlier in life when compared to other racial and ethnic groups [17]. This is reflected in data not only for African-American men, but also for Caribbeans, and Black men in Europe, suggesting that they possess a common genetic background more prone to the development of the cancer. Of note, Chu et al [18] reported that incidence rates of prostate cancer were as much as 40 times higher among African-American men than those in Africa. These differences suggest that environmental factors also play an important role in the etiology of the prostate cancer and variations in incidence may be due to underdiagnosis, differences in the screening methods and disparities in healthcare access.

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