lunes, 11 de junio de 2018

Prostate Cancer Epidemiology Worldwide

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By Lois Zoppi, BA

Prostate cancer is one of the leading causes of death globally. It only affects men, and the risk of developing prostate cancer increases with age.

Image Credit: SewCream / Shutterstock

Prostate cancer is one of the leading causes of death due to cancer, and is the most diagnosed non-skin cancer in the United States. Its incidence in developing countries is also increasing. In 2012, an estimated 1.1 million men worldwide were diagnosed with prostate cancer.

Genetic risk factors

Age

Around 42% of prostate cancer cases are seen in men over 50 years of age, with cases most commonly seen in men older than 60 years. As life expectancy continues to increase, it is anticipated that prostate cancer incidence will also increase.

Men who have a family history of prostate cancer are urged to be screened for the disease at around 40 years of age as their incidence risk is significantly increased, especially if the affected family member is a brother.

Sex

As the prostate gland is only present in men, women cannot develop prostate cancer.

Race

African-American Caribbean men show the highest incidence rates of prostate cancer. The mortality rate due to prostate cancer for African-American men is around double than that of white men.

This could be due to restricted access to appropriate health care. The incidence of prostate cancer in non-Hispanic white men is also lower compared to Asian-American and Hispanic/Latino men.

Weight

There is some contradiction in results regarding the effect obesity has on the incidence of prostate cancer. According to research by the American Cancer Society, one out of five cancer deaths is linked to obesity. In general, the risk of prostate cancer in obese men is considered higher than in other groups. Further study into this area is needed to produce conclusive results.

Family history

Similarities in lifestyle, environmental conditions, and genes all contribute to the prevalence of hereditary prostate cancer. Studies have shown that men over 75 years of age with a family history of prostate cancer have a 30-60% chance of developing the disease.

According to the American Cancer Society, having a father or brother with prostate cancer more than doubles the risk of developing prostate cancer. It is estimated that hereditary prostate cancer accounts for 5-10% of all cases.

Men who have a family history of prostate cancer are advised to be screened for prostate cancer at around 40 years of age, as their risk of developing the disease significantly increases, especially if the affected family member is a brother.

Diet and lifestyle

Studies have also shown a link between increased alcohol intake, smoking and prostate cancer prevalence, but a direct link is yet to be made.

Increased consumption of fruit and vegetables including pomegranate juice, tomatoes, soy beans, legumes, and cruciferous vegetables like broccoli has been shown to be beneficial in decreasing the incidence of prostate cancer. High calcium intake may slightly increase the risk of prostate cancer.

There have been links between excessive use of micronutrients and supplements and prostate cancer, although the reason why micronutrient intake affects prostate cancer is unclear.

Sexual activity and sexually transmitted diseases

Some studies have shown that ejaculation frequency can prevent the development of prostate cancer. A 2014 study showed that men who ejaculated more than five times per week, had a lower risk of developing prostate cancer.

Other studies showed similar results with increased number of ejaculations (21 times per week). It is not yet understood why increased ejaculation has a protective effect on the incidence of prostate cancer.

However, increased sexual activity is also linked with higher chances of contracting sexually transmitted diseases (STDs) such as gonorrhoea and human papillomavirus (HPV).

Environmental factors

Incidence rates of prostate cancer are high in Western and Northern Europe, Northern America, Australia, and New Zealand as prostate specific antigen testing (PSA) is common in these areas. The Caribbean and South Africa also see high incidence rates (79.8%, 61.8%, and 60.1% respectively), while rates in Asian populations remain low at 10.5% and 4.5% for Eastern and South-Central Asia, respectively.

Mortality rates see less variation worldwide. Rates are high in mainly black populations such as in the Caribbean and sub-Saharan Africa, but are very low in Asia.

Prognosis

In many cases, prostate cancer is slow-growing and non-invasive. The American Cancer Society has estimated that 91% of patients have a 10-year survival rate. In developing countries, the survival rate is lower due to delayed diagnosis, restricted health care access, and inadequate treatment.

Overall, more research needs to be conducted to solidify links seen between the incidence of prostate cancer, diet and vitamin intake, and sexual activity. There are clear links between age and prostate cancer incidence.

Global incidence and mortality rates vary widely due to an imbalance in the available preventative and diagnostic services among the countries. Incidence rates are significantly higher in Australia/New Zealand, Northern American and Northern and Western Europe than in Asia.

Reviewed by HH Patel, M.Pharm