Proton beam therapy for a patient with prostatic rhabdomyosarcoma: a case report and review of the literature

Abstract

Rhabdomyosarcoma (RMS) is a malignant tumor that is more common in children and rarely occurs in adults. Its prognosis mainly depends on the tumor stage and genetic type. In the past few decades, the survival rate of rhabdomyosarcoma has been significantly improved. Embryonal rhabdomyosarcoma (ERMS), alveolar rhabdomyosarcoma (ARMS), and pleomorphic rhabdomyosarcoma (PRMS) are common types of rhabdomyosarcoma. ERMS and ARMS are more common in children, while PRMS is more common in adults and has a poor prognosis. We report a case of a 40-year-old patient with ARMS. His chief complaint was difficulty urinating. The diagnosis was confirmed by puncture biopsy of the prostate, and pelvic lymph node metastasis was already present at the time of diagnosis. The patient underwent seven courses of chemotherapy and proton therapy and five courses of adjuvant chemotherapy. Unfortunately, 8 months after proton beam therapy, the patient showed disease progression (bone metastasis). This case illustrates the difficulties in managing late-stage prostatic alveolar rhabdomyosarcoma and is the first case reported in our hospital to be treated with proton beam therapy in an adult with ARMS of the prostate.

Keywords: alveolar rhabdomyosarcoma; chemotherapy; prostate; proton beam therapy; rhabdomyosarcoma.

Figure 1

The mass infiltrates the whole prostate and the right lateral wall of the urinary bladder. The right lower ureter was infiltrated by the lesion. Large lymph nodal mass was also seen in the pelvis with multiple retroperitoneal lymphadenopathies (a&b, white arrow). Pelvic MRI showed suspicion of prostate cancer, invasion of the bladder base and seminal vesicles on both sides, multiple enlarged lymph nodes in the bilateral pelvis, and retroperitoneal lymph node metastasis (c&d, white arrow). The PET-CT 8 months after PBT showed that the prostate lesions were basically under control and the metastatic lymph nodes in the pelvis were significantly reduced (e&f, white arrow). PET-CT showed multiple bone metastases (e, red arrow).

Figure 2

Before the protontherapy, two gold markers were inserted on the prostate (a&b, red arrow). Hydrogel (a, white arrow) was inserted between the rectum and the prostate (better to protect the rectum).

Figure 3

Proton dose distribution cloud map of the retroperitoneal lymphatic drainage area (a, dark green area), retroperitoneal metastatic lymph nodes (a, red area) and pelvic lymphatic drainage area (b, dark green area) and GTV (b, red area). The isodose distribution for proton therapy (c&d). GTV, gross target volume.