Testicular cancers are classified based on their cell of origin: seminomatous, non-seminomatous, Leydig, Sertoli, choriocarcinoma, embryonal, teratoma, and yolk-sac derivatives. Seminoma and non-seminomatous lesions are frequently grouped as germ cell tumors and are notable for their responsiveness to chemotherapy compared to the other types. Seminoma accounts for about a third of all testicular germ cell malignancies and is one of the most treatable cancers, with a survival rate of 98% to 99% in early-stage disease.
The exact etiology of seminoma is unknown. The most current theory is that environmental endocrine disrupters exert estrogenic and/or antiandrogenic activities, contributing to the arrested development of the gonocyte. The disease probably develops as carcinoma in situ during a short phase of intrauterine growth. One widely accepted theoretical concept is testicular dysgenesis syndrome (TDS). TDS groups germ cell tumors, impaired spermatogenesis, cryptorchism, and hypospadias based on reports that they share some common risk factors hypothesized to originate during fetal life. An increased incidence is reported during the past several decades. Roughly 10% of all patients with germ cell tumors had a personal history of cryptorchidism.
A patient with an undescended testicle has at least four times the risk for carcinoma compared to a normal testicle. This risk is increased regardless of the age at repair. Patients with Trisomy 21 are 50 times more likely to have testicular cancer. There is evidence of a recessive gene inheritance in familial testicular cancer. In a Japanese population, this association was linked to the HLA class II allele DRB1*0410. In a United Kingdom study, it seemed to be associated with a homozygous allele of the GSTP1 locus and expansion of (CAG)n repeats.
Testicular germ cell tumors (GCT) are the most common solid malignancies affecting young males (age 15 to 45). It is ten times more common in males of northern European ancestry and five times more common in all White-race males as compared to others. The overall prevalence of seminoma generally increases with age.
Testicular seminoma originates in the germinal epithelium of the seminiferous tubules. The disease is thought to result from the proliferation of immature spermatogonia. Arrested gonocyte maturation with the persistence of embryonic features and correspondingly increased genomic instability is the most probable model for the pathogenesis of CIS. The transition from the precursor lesion to invasive cancer is associated with a gain of the short arm of chromosome 12, Isochromosome i(12p), likely involving KRAS2 and possibly NANOG (pseudogenes). The exact mechanism is unknown. However, there is also an increased frequency of isozymes of 7, 15, 19, and X in seminoma.
There are three main pathologic categories of testicular seminoma: classical, spermatocytic, and seminoma with syncytiocytotrophoblastic cells. Spermatocytic type is rare, occurs in older men, and appears to have a better prognosis. The syncytiocytotrophoblastic subtype is associated with increased serum βhCG levels. A seminoma with a high mitotic index (>3 mitotic figures/HPF) is designated an anaplastic seminoma. The name implies a more aggressive tumor, but research fails to support that concern.
Exposure to various factors in adolescence and adulthood appears linked to the development of testicular cancer. Firefighters and aircraft maintenance personnel, and farmers exposed to organochloride pesticides appear to have an increased risk of developing testicular cancer. Case-control studies have revealed significant associations between seminoma and levels of cis-nonachlor, trans-nonachlor, oxychlordane, and total chlordane.
Ochratoxin A, a substance less well-studied, naturally occurs in the mold in grains, coffee, nuts, and spices that have recently been linked to testicular cancer.
Patients usually present with an asymptomatic testicular mass, which may be associated with infertility. Testicular pain from malignancy is relatively rare but still should be included in the differential diagnosis.
On physical exam, there is usually a unilateral, firm to hard palpable mass in the scrotum, which is localized to the testis. This may be associated with a hydrocele that would preclude palpation, so testicular ultrasonography may be needed to identify the mass. Metastatic disease, although rare, can present initially with lymphadenopathy in the retroperitoneum and the anterior mediastinum. Even massive metastatic disease can be produced from a non-palpable testicular malignancy.
Typically, testicular ultrasonography shows an intratesticular mass that is relatively hypoechoic and homogeneous. As the mass increases in size, it may become less homogeneous due to hemorrhage and necrosis.
The initial evaluation is by testicular ultrasonography. A CT scan of the abdomen and pelvis is the initial staging modality, but it may fail to identify retroperitoneal nodes in 15% to 20%. A chest CT is usually recommended only when there is an abnormal chest x-ray first. PET scanning is not usually part of the initial workup but may be useful in tracking activity and growth in residual masses following definitive chemotherapy.
Several laboratory values may be useful in following tumor burdens. These include AFP, B-HCG, and LDH. Alpha-fetoprotein (AFP) elevation indicates at least some nonseminomatous disease, and those patients are then treated as nonseminomas, germ cell patients. LDH may be used to follow the overall seminomatous tumor burden. Beta-human chorionic gonadotropin (HCG) is present in 5% to 10% of seminoma patients; these usually demonstrate the syncytial cytotrophoblastic subtype. Such elevations tend to be associated with metastatic disease, but the beta-HCG elevation by itself has no connection with overall survival.
As noted earlier, a plain chest film may reveal metastatic disease, and chest CT is only indicated to evaluate abnormalities on the plain abnormalities. Ultrasound is typically the most useful diagnostic method for the follow-up of metastatic masses.
Several treatment options are available to these patients, but surgery, a radical orchiectomy, is almost always the primary intervention. The surgical approach usually requires an incision in the groin with the removal of the entire testicle and most of the spermatic cord. This is called a radical inguinal orchiectomy and is both therapeutic and a part of the staging procedure. A scrotal incision approach should be avoided in any orchiectomy or surgical testicular exploration where malignancy is suspected.
Stage 1 disease may be offered single therapy with carboplatin, and for more advanced disease, bleomycin, etoposide, and cisplatin (BEP) or etoposide and cisplatin (EP) may be used.
Most men do not have a significant decrease in testosterone or low testosterone symptoms of sexual dysfunction with the removal of a single testicle. The procedure is not usually a cause of infertility, and 25% of men with testicular malignancies are already infertile before getting a testicular cancer diagnosis.
Sperm counts may increase after removal of the cancerous testicle. Reconstructive surgery with a prosthetic testicle is an option that may be exercised with the primary operation delayed until active treatment is done or completely declined. Retroperitoneal lymph node dissection is more complex and invasive. It is used for staging and is usually open, but laparoscopic approaches are being developed. Complications include immediate problems, such as infection or bowel blockage, and loss of the ability to ejaculate. For these reasons, retroperitoneal lymph node dissections are rarely done for seminoma except possibly for growing, residual abdominal masses not responding to other treatments. Radiation or chemotherapy generally is indicated for the management of positive lymph nodes.
NCI has a Phase III clinical trial named Retroperitoneal Lymph Node Dissection in Treating Patients with Testicular Seminoma with Lymphadenopathy or Stage I-IIB Testicular Seminoma.
Sloan Kettering has a Phase I/II Study of Topical SOROO7 in Patients with Skin Metastasis from Cancer.
Testicular seminoma is a germ cell tumor, which is very sensitive to radiation therapy. Radiation therapy planning is based on the results of a contrast-enhanced CT of the chest, abdomen, and pelvis. The optimal IMRT dose has been decreased to 20 to 25 Gy in CS I and to 30 to 36 Gy in CS IIs. Because of low pelvic relapse rates reported in stage I tumors (less than 5%), the indication for pelvic irradiation is no longer. This omission increases post-treatment fertility rates and diminished gastrointestinal toxicity. The optimal RT dose generally recommended is between 25 and 30 Gy in 15 to 20 fractions. Because left-sided primaries tend to relapse around the insertion of the left testicular vein the, left para-aortic region must be included in the irradiated volume. Radiation therapy planning is based on the results of a contrast-enhanced CT of the chest, abdomen, and pelvis.
Volumetric modulated arc therapy radiotherapy has been studied in which radiation is delivered continuously as the treatment gantry rotates around the patient. With this approach, there is a greater spread of low-dose radiation in healthy tissues.
Proton (PT) pencil scanning beam therapy provides unique depth dose characteristics of protons. There is a significant reduction of doses to adjacent critical structures proximal and distal to the target volume in comparison to more traditional treatments. This therapy allows escalation of doses delivered to the tumor and normal tissue, sparing reducing toxicity and improving quality of life. This is possible only if the proton machine employs the pencil scanning beam, which avoids the production of neutrons and reduces the dose delivered to the total body. Proton therapy is recommended in pediatric patients because of the tenfold decrease in radiation dose.
The optimal IMRT dose decreased to 20 to 25 Gy in CS I and 30 to 36 Gy in CS IIs.
In one study from Mass General, photon beams were weighted to yield a maximum of 26 Gy(RBE) and a minimum of 25.5 Gy(RBE) in 1.5 Gy(RBE)/fraction to the CTV. A 5 mm compensator expansion was added for proton plans to emulate a PTV expansion in photon treatment planning.
Proton pencil beam scanning allows more precise targeting of the tumor with a 10 fold decrease in total radion dose compared with IMRT.
Bleomycin, etoposide, and cisplatin (BEP) or etoposide and cisplatin (EP) are the two most common chemotherapy regimens. Recent studies suggest that 3 cycles are as effective as 4, with fewer side effects.
Staging: The TNM System
In the Numerical System
Management (National Comprehensive Cancer Network - NCCN Guidelines)
Stage 0 Seminomas
Carcinoma in situ (CIS) where the levels of tumor markers like HCG and AFP are not elevated. Treatment may not be needed as long as there are no signs that the CIS is growing or turning into invasive cancer. (The diagnosis is typically made via a biopsy.) If CIS is treated, it is with an orchiectomy (to remove the testicle) or with testicular radiation.
If tumor marker levels are high, then the cancer is not stage 0, even when only CIS is found in the testicle, and there are no signs of cancer spread. These cases are treated like stage I cancers. CT scan of the abdomen and pelvis is required to verify the extent of the malignancy in such cases.
All of the following cancers are treated initially with initial radical orchiectomy. After surgery, there may be several treatment choices as follows:
Stage I Seminomas
Stage II A
Stage II B and C
Small tumors are often watched with CT scans to see if they grow. If they do, further treatment is needed. If the tumors are detected on a PET scan, surgery, or different chemotherapy is indicated.
Stage IV refers to cancer that has spread to any other organ.
According to the Testicular Cancer Society: "The overall survival rate is greater than 95%. If diagnosed early, while the cancer is confined to the testicle, the survival rate is 99%. If the cancer has spread to regional lymph nodes, the survival rate is 96%, and even if there are distant metastases, the survival rate is over 70%."
Reconstructive surgery with a prosthetic testicle is an option that may be exercised with the primary operation delayed until active treatment is done or completely declined.
Surveillance for all stages may include interval CT.
The Testicular Cancer Resource Center recommended follow-up:
Princess Margaret Hospital Protocol
Because evidence suggests that TGCT is initiated in early life, exposure to these persistent organic pesticides during fetal life or breastfeeding should be avoided.
There is no recommended protocol for screening for testicular cancer; however, young men must be taught to perform testicular self-exam. Education must include evidence of excellent prognosis of early-stage disease. More than half of solid, palpable intratesticular masses are non-germ cell tumors.
Pelvic nodes are anatomically near to L1-L4 sympathetic roots of the superior hypogastric plexus. When oncologically possible, they should be surgically spared, at least unilaterally, to preserve ejaculatory function.
Contrary to non-seminomatous germ cell tumors, retroperitoneal lymph node dissection (RPLND) is not indicated in seminomas.
Excellent treatment survival rates have been accomplished; the focus should now be placed on identifying early-stage disease. Patients need to be able to examine themselves and be educated about the successful management of early disease.
Primary care providers, including nurse practitioners, must know that urgent testicular ultrasound is indicated for a new testicular mass. The oncology team needs to educate the patients on options for their disease stage with continued emphasis on minimizing complications of therapy. Further paths of inquiring may establish optimal surveillance schedules.
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