What are the other Names for this Condition? (Also known as/Synonyms)

• Well-Differentiated NET of the Genitourinary System
• Well-Differentiated NET of the Urogenital System
• Well-Differentiated Neuroendocrine Tumor of the Urogenital System

What is Well-Differentiated Neuroendocrine Tumor of the Genitourinary System? (Definition/Background Information)

• Well-Differentiated Neuroendocrine Tumor of the Genitourinary System is a rare low-grade tumor that is seen in the genitourinary tract; the genitourinary or urogenital system includes the urinary and genital organs
• Neuroendocrine Tumors (NETs) are tumors showing neuroendocrine differentiation
• Most of the tumors are observed in the kidney and bladder, while other locations include the urethra, prostate, and testis

Incidence:

• The kidney and urinary bladder neuroendocrine tumors occur in wide range of patients
• Studies have shown the tumor to have a median incidence of 53 years
• The tumors are exceedingly rare, especially in the prostate, testis, and urethra
• Both males and females are equally affected
• All races and ethnic groups are at risk

Risk factors:

• 15% of kidney NETs tumors have been reported in individuals with an anatomical defect called horseshoe kidney
• Other risk factors have not been well-characterized

Cause:

• The cause of tumor formation is unknown
• Studies have shown the tumors to have multiple molecular abnormalities including loss of heterozygosity (LOH) on short arm of chromosome 3 at location p21
• Mutations in CDH1 and TET2 genes have been reported

Signs and symptoms:

• The tumors can arise in a variety of anatomical locations including the kidney, urinary bladder, prostate gland, testicles, and urethra
• Depending on the location of the tumor, the signs and symptoms vary
• The tumors arising in kidney usually results in abdominal pain and blood in urine (hematuria).  Urinary bladder tumors present blood in urine
• Some of the individuals with these tumors known to have carcinoid syndrome resulting in signs and symptoms such as:
  • Flushing of the face
  • Skin lesions on the face
  • Breathing difficulties
  • Rapid heartbeat
  • Diarrhea
• The tumors vary in size from individual to individual (mean size is about 5 cm)
  • In some individuals, large sizes have been reported; some renal NETs have been described that are nearly 30 cm in size
  • Tumors in the urinary bladder and urethral anatomical sites are usually much smaller measuring 0.3 cm to 1.2 cm in size

Diagnosis: A vast majority of the tumors are detected incidentally.

• Blood and urine tests
• Radiological studies
  • Ultrasound of abdomen
  • CT and MRI scan of abdomen
• Tissue biopsy of the tumor mass can help achieve a definitive diagnosis:

Complications:

• Emotional stress
• Tumor metastasis to different organs and regions
• Incomplete removal results in tumor recurrence

Treatment:

• The staging of the tumor is performed according to AJCC classification. The staging depends on the site of origin of the tumor
• Treatment depends on the location and the size of the tumor
• It may require a combination of surgery, chemotherapy, and radiation therapy

Prevention: Presently, it is not possible to prevent the formation of Well-Differentiated Neuroendocrine Tumors of the Genitourinary System.

Prognosis: The prognosis is difficult to ascertain since the tumors are extremely rare.

• In general, the stage of the tumor is extremely important when determining the prognosis.  Lower stage tumors have better prognosis than higher stage tumors
• The value of Ki-67 proliferative index could be an important factor in determining the prognosis.  The Ki-67 proliferative index is evaluated by a pathologist when the tumor specimen is examined under the microscope using special immunohistochemical stain
• Studies have shown that bladder NETs generally have a better prognoses due to their small sizes and superficial locations