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Rhabdomyosarcoma of the Bladder

Definition and Epidemiology

Sarcoma of the bladder is a rare malignant tumor that derives from connective tissue cells of the bladder.

Epidemiology

Rhabdomyosarcoma has a share of 1–3% of all pediatric cancer cases, and the incidence is 3–7 cases per 1 million children, depending on age. 20% of rhabdomyosarcoma arise from the urogenital tract, with the most frequent localization in the prostate, bladder, and paratesticular, rarely uterus and vagina. Peak incidence in the first two years.

Etiology and Genetics

Genetic risk factors:

• Li-Fraumeni syndrome: a marked increased sarcoma and carcinoma risk is caused by p53 suppressor gene mutation.
• Neurofibromatosis type I
• Beckwith-Wiedemann syndrome
• Costello syndrome and Noonan syndrome
• DICER1 syndrome

Pathology of Bladder Sarcoma

Histological typing:

The most common histological types are rhabdomyosarcoma in children and leiomyosarcoma in adulthood:

• Embryonal rhabdomyosarcoma: the most common type of urogenital rhabdomyosarcoma in children, sometimes with grapevine-like growth (Sarcoma botryoides) and a relatively good prognosis.
• Alveolar rhabdomyosarcoma: more common in extremities than urogenital rhabdomyosarcoma in children, has a poor prognosis, especially with PAX3-FOXO1 gene fusion.
• Rare rhabdomyosarcomas: spindle cell/sclerosing rhabdomyosarcoma and pleomorphic rhabdomyosarcoma.
• Leiomyosarcoma: the predominant type in adults.
• Rarities: Angiosarcomas, fibrosarcomas, lymphosarcomas.

TMN Staging (UICC 2017):

• T1: confined to the site of origin.
• T2: invasive into surrounding tissues.
• • T2a: ≤5 cm
  • T2b: >5 cm
• T3: tumor size 10--15 cm or macroscopic tumor growth beyond the serosa.
• T4: multifocal or large Tumor >15 cm.
• N0: no regional lymph node metastasis.
• N1: regional lymph node metastasis.
• M0: no distant metastasis.
• M1: distant metastasis.
• Grading: G1: well differentiated, G2: moderately differentiated, G3: poorly differentiated.

Signs and Symptoms of Bladder Sarcoma

Subvesical obstruction with lower urinary tract symptoms, hematuria, urinary retention, disturbed defecation, abdominal pain, and palpable lower abdominal tumor.

Diagnostic Workup of Bladder Sarcoma

• Imaging: CT scan or better MRI of abdomen and pelvis, chest x-ray and, if necessary, bone scintigraphy and chest CT scan.
• Biopsy: small biopsy of the tumor, depending on the localization, either with cystoscopy and TURB or TRUS and needle prostate biopsy.

Treatment of Bladder Sarcoma

Treatment of Rhabdomyosarcoma of the Bladder:

Treatment should be carried out within clinical trials to improve the treatment of this rare disease. After diagnosis, the patients are stratified to an appropriate study protocol in relation to the tumor stage and risk group. The following factors are considered: tumor location, tumor size, histology, grading, lymph node involvement, metastases, and results of surgical treatment. Study protocols are, e.g., Children's Oncology Group (COG), which is the successor of the Intergroup Rhabdomyosarcoma Study Group (IRSG) or European Cooperative Groups (SIOP).

IRS-Grouping is used both by COG and European study groups.

• Group I: localized tumor, completely resected.
• Group IIA: grossly resected tumor with microscopic residual disease.
• Group IIB: regional disease with lymph node metastases, completely resected with no evidence of microscopic residual disease, most distant lymph nodes without metastasis.
• Group IIC: regional disease with lymph node metastases, grossly resected but with evidence of microscopic residual disease or metastases in most distant lymph nodes.
• Group III: incomplete resection or biopsy with macroscopic residual disease.
• Group IV: distant metastases.

The goal of rhabdomyosarcoma treatment is healing and preserving a functional lower urinary tract. A tumor resection is performed when the bladder can be spared (partial cystectomy). Since the most common tumor sites are the trigone and the prostate, primary bladder-sparing surgery is not possible. This group of patients will receive a neoadjuvant treatment with chemotherapy and possibly radiation. The subsequent operation can be performed with a bladder-preserving technique in over half of the cases. Effective chemotherapeutic agents are vincristine, actinomycin D, cyclophosphamide, adriamycin, etoposide, and ifosfamide, which are used in various combinations. The role of neoadjuvant radiation is controversial, because the tumor resection and reconstruction of the urinary tract becomes more difficult (Filipas et al., 2004). Also controversial is the technique of urinary diversion after cystectomy. Some authors advocate a transient incontinent urinary diversion until the oncological risk can be finally assessed, and re-operations are unlikely. Others advocate continent urinary diversion with the primary tumor resection; this should be limited to situations with a good prognosis.

Treatment of Leiomyosarcoma of the Bladder:

Bladder leiomyosarcoma in adults is treated with radical surgery (cystoprostatectomy), followed by adjuvant irradiation and/or chemotherapy.

Related diseases

• Sarcoma of the prostate
• Paratesticular rhabdomyosarcoma

References

National Cancer Institute: Childhood Rhabdomyosarcoma Treatment (PDQ)–Health Professional Version https://www.cancer.gov/types/soft-tissue-sarcoma/hp/rhabdomyosarcoma-treatment-pdq

HAYS, D. M.: Bladder/prostate rhabdomyosarcoma: results of the multi-institutional trials of the Intergroup Rhabdomyosarcoma Study.
In: Semin Surg Oncol
9 (1993), Nr. 6, S. 520–3

Filipas, D.; Fisch, M.; Stein, R.; Gutjahr, P.; Hohenfellner, R. & Thüroff, J. W. Rhabdomyosarcoma of the bladder, prostate or vagina: the role of surgery.
BJU Int, 2004, 93, 125-129.

Linardic CM. PAX3-FOXO1 fusion gene in rhabdomyosarcoma. Cancer Lett. 2008 Oct 18;270(1):10-8. doi: 10.1016/j.canlet.2008.03.035. Epub 2008 May 23. PMID: 18457914; PMCID: PMC2575376.

NIGRO, K. G. ; MACLENNAN, G. T.: Rhabdomyosarcoma of the bladder and prostate.
In: J Urol
173 (2005), Nr. 4, S. 1365

  Deutsche Version: Sarkom der Harnblase