TESTICULAR CANCER

Testicular cancer: epidemiology and aetiology
Incidence and mortality
Primary testicular cancer (TC) is the most common solid cancer in men aged 20 - 45; rare below 15 years and above 60 years. Constituting 1 - 2% of all male cancers, the lifetime risk of developing testicular cancer is 1 in 500. It is also considered the most curable cancer, with 1990 new cases but only 68 deaths in the UK (2001). It is increasing in incidence; reported to affect 7 per 100,000 men. Public health campaigns encouraging testicular self-examination (TSE) for young men are ongoing.

Epidemiology and aetiology
- Age: the most common affected age group is 20 - 45 years, with germ cell tumours; teratomas are more common at ages 20 - 35; while seminoma is more common at ages 35 - 45 years. Rarely, infants and boys below 10 years develop yolk sac tumours and 50% men >60 years with TC have lymphoma.
- Race: white people are three times more likely to develop TC than black people in the USA.
- Cryptorchidism: 10% of TC occur in undescended testes: the risk increases by 3 - 14 times compared to men with normally descended testes. Ultrastructural changes are present in these testes by age 3 years, although earlier orchidopexy does not completely eliminate the risk of developing TC. 5 - 10% of patients with a cryptorchid testis develop malignancy in the normally descended contralateral testis.
- Intratubular germ cell neoplasia (IGCN): synonymous with carcinoma in situ, although the disease arises from malignant change in spermatogonia. 50% of cases develop invasive germ cell TC within 5 years. The population incidence is 0.8%. Risk factors include cryptorchidism, extra-gonadal germ cell tumour, previous or contralateral TC (5%), atrophic contralateral testis, 45XO karyotype, and infertility.
- Human immunodeficiency virus (HIV): patients infected with the HIV virus are developing seminoma more frequently than expected.
- Genetic factors appear to play a role, given that first-degree relatives are at higher risk, but a defined familial inheritance pattern is not apparent.
- Maternal oestrogen ingestion during pregnancy increases the risk of cryptorchidism and TC in the male offspring.
Trauma and viral-induced atrophy have not been convincingly implicated as risk factors for TC.

Bilateral testicular cancer
occurs in 1 - 2% of cases.

Testicular cancer: clinical presentation
Symptoms
Most patients present with a scrotal lump, usually painless or slightly aching. Delay in presentation is not uncommon, particularly those with metastatic disease. This may be due to patient factors (fear, self-neglect, ignorance, denial) or earlier misdiagnosis. Occasionally (5%) acute scrotal pain may occur, due to intra-tumoural haemorrhage, causing diagnostic confusion. The lump may have been noted by the patient, sometimes after minor trauma, or by his partner. In 10%, symptoms suggestive of advanced disease include weight loss, lumps in the neck, chest symptoms, and bone pain.

Signs
Examination of the genitalia should be carried out in a warm room with the patient relaxed. Observation may reveal asymmetry or slight scrotal skin discolouration. Using careful bimanual palpation, the normal side is first examined, followed by the abnormal side. This will reveal a hard, non-tender, irregular, non-transilluminable mass in the testis, or replacing the testis. Care should be taken to assess the epididymis, spermatic cord, and overlying scrotal wall, which may be normal or involved in 10 - 15% of cases. Rarely, a secondary hydrocoele may be present if the tunica albuginea has been breached. General examination may reveal cachexia, supraclavicular lymphadenopathy, chest signs, hepatomegaly, lower limb oedema, or abdominal mass all suggestive of metastatic disease. Gynaecomastia is seen in ~5% of patients with TC, due to endocrine manifestations of some tumours.

Differential diagnosis
Testicular torsion, epididymo-orchitis, hydrocoele, epidiymal cyst, hernia, haematoma, or syphilitic gumma (rare). The majority of scrotal lumps are harmless lesions, but no risks should be taken. Every patient who is concerned should be seen, examined, and if any doubt persists, should be investigated further.

Investigations
Ultrasound is an extension of the physical examination and will confirm that the palpable lesion is within the testis, distorting its normally regular outline and internal echo pattern. Any hypoechoic area within the tunica albuginea should be regarded with suspicion. It may distinguish a primary from a secondary hydrocoele. Ultrasound may also be used to identify impalpable lesions as small as 1 - 2mm an  occult primary tumour in a patient presenting with systemic symptoms and signs or an incidental finding.
Abdominal and chest CT scans are usually obtained for staging purposes if the diagnosis of TC is confirmed or considered likely.
Serum tumour markers are measured prior to any treatment of a confirmed testicular mass