Testicular Cancer

 What we know
 Incidence
 Environmental risk factors

What we know

Cancer develops when cells in a part of the body begin to grow out of control. Testicular cancer develops from within the cells in the testes and is the result of abnormal germ cell development. The main symptoms are a lump or enlargement that develops in one or both of the testes, a feeling of heaviness in the scrotum, or discomfort in a testicle or scrotum. Two types of testicular cancer exist: seminomas, the most common germ cell tumour and nonseminomas.

Incidence

Testicular cancer is a rare cancer (about 1% of all male cancers) but its incidence is rising (Figure 2). Increases of 1–6% per annum have been reported for both seminomas and nonseminomas. It is now the most common malignancy of young men in many countries. Estimates suggest there are 50,000 cases worldwide, approximately 21,000 of which occur in Europe.

Overall, rates of testicular cancer in the developed regions of the world are five times higher than those in the less developed regions. Within the European Union (EU), there is an approximately five-fold variation in incidence between countries with the highest and lowest incidence rates. For example, whilst Denmark, Germany and Austria report age-standardised rates (ASRs) of around 10 per 100,000, Lithuania, Estonia, Spain and Latvia have ASRs of around 2 per 100,000 (Figure 1).

Figure 1: Age Standardises European incidence rates, testicular cancer, males, EU, 2002 estimates, Cancer Research UK [1] Enlarge the picture

Figure 2: Age Standardised rates for incidence of testicular cancer [2] Enlarge the picture

The exact reason why a cell becomes cancerous is unknown. Despite the increase in the disease the causes of testicular cancer are unknown.

The main risk factors are:
 An undescended testicle – known as cryptorchidism, a common congenital abnormality in males
 Age – Testicular cancer is more frequently diagnosed in young and middle- aged men, between the ages of 15 – 45.
 Ethnic group – testicular cancer is more common in Caucasians
 Inherited factors may play a role in a small number of testicular cancers. Having a father or a son who has had testicular cancer increases the risk of getting the disease.
 Low birth weight

Environmental risk factors

Increasing incidence of testicular cancer reported in countries in the Western world coupled with the rise in chemical exposures over the last century have lead some scientists to postulate the involvement of environmental factors in testicular cancer etiology, in particular prenatal exposure to chemical compounds that mimic or interfere with the hormone signalling pathways that regulate fetal development. These compounds are known as endocrine disrupting chemicals (EDCs). Those with potential effects on male reproductive health include xenoestrogens (chemicals that mimic hormones responsible for female sexual development and reproduction) and anti-androgens (chemicals that interfere with the androgen hormones responsible for the development and maintenance of the male sexual characteristics).

It is thought that exposure to xenoestrogens and anti-androgens in the womb may affect the development of the testes, setting in motion a chain of cellular event that will eventually lead to testicular cancer. A study of organochlorines, fat-soluble chemicals that bioaccumulate in the human body, found higher concentrations of the chemicals in mothers of patients with testicular cancer, suggesting a link [3].

Furthermore it has been suggested that several male reproductive health problems including testicular cancer have a common origin in fetal development. The term “testicular dysgenesis” has been coined to describe the group of disorders involved. For more information please the “Testicular Dysgenesis” webpage.

The continued search for the causes of testicular cancer may reveal preventable risk factors. In the meantime precautionary measures to reduce exposure to certain endocrine disrupting chemicals are warranted, particularly in light of their suggested link to other cancers.

 For more information please see the Collaborative on Health and Environment Cancer Working Group