Successful Radiotherapy for Advanced Small Cell Carcinoma of the Prostate with Syndrome of Inappropriate Secretion of Antidiuretic Hormone

Primary small cell carcinoma of the ureter with associated hyponatremia and rapid progression to bladder involvement: a case report

Background

Primary small cell carcinoma (SmCCa) of the ureter is rare. The majority of patients present with visible haematuria. Diagnosis is confirmed by histopathology. Associated hyponatraemia in GU lesion can be due SmCCa can be useful for early diagnosis aggressive ureteric tumors. The current management includes radical surgery or radiotherapy with concomitant chemotherapy to improve survival and quality of life.

Case presentation

We present a case of a 77 years female who was found to have unilateral hydronephrosis with a 5 cm filling defect in the distal ureter on CT urogram. Further staging showed organ-confined disease. Serum sodium levels were low at presentation. At the time of planned nephroureterectomy (NU), cystoscopy revealed a bladder tumor obstructing the right ureteric orifice. TURBT was performed instead. After TURBT, there was marked hyponatremia and histology was small cell carcinoma (SmCCa). Paraneoplastic SIADH was the likely cause. Neoadjuvant chemotherapy (NACT) followed by radiotherapy (RT) was chosen for definitive treatment. This resulted in an excellent response supported by radiological evidence of almost complete resolution of the tumor.

Conclusion

The presence of genitourinary lesion and hyponatremia should raise suspicion of paraneoplastic SIADH. The case suggests the emphasis of histological diagnosis of the genitourinary lesion with existing hyponatraemia to provide better outcome with NACT followed by definitive treatment. We share our experience of NACT and RT in the management of ureteric SmCCa extension to the bladder.

Exploiting Dependence of Castration-Resistant Prostate Cancer on the Arginine Vasopressin Signaling Axis by Repurposing Vaptans

Men with advanced prostate cancer are treated by androgen deprivation therapy but the disease recurs as incurable castration-resistant prostate cancer (CRPC), requiring new treatment options. We previously demonstrated that the G protein-coupled receptor (GPCR) arginine vasopressin receptor type1A (AVPR1A) is expressed in CRPC and promotes castration-resistant growth in vitro and in vivo. AVPR1A is part of a family of GPCR's including arginine vasopressin receptor type 2 (AVPR2). Interrogation of prostate cancer patient sample data revealed that coexpression of AVPR1A and AVPR2 is highly correlated with disease progression. Stimulation of AVPR2 with a selective agonist desmopressin promoted CRPC cell proliferation through cAMP/protein kinase A signaling, consistent with AVPR2 coupling to the G protein subunit alpha s. In contrast, blocking AVPR2 with a selective FDA-approved antagonist, tolvaptan, reduced cell growth. In CRPC xenografts, antagonizing AVPR2, AVPR1A, or both significantly reduced CRPC tumor growth as well as decreased on-target markers of tumor burden. Combinatorial use of AVPR1A and AVPR2 antagonists promoted apoptosis synergistically in CRPC cells. Furthermore, we found that castration-resistant cells produced AVP, the endogenous ligand for arginine vasopressin receptors, and knockout of AVP in CRPC cells significantly reduced proliferation suggesting possible AVP autocrine signaling. These data indicate that the AVP/arginine vasopressin receptor signaling axis represents a promising and clinically actionable target for CRPC.

IMPLICATIONS

The arginine vasopressin signaling axis in CRPC provides a therapeutic window that is targetable through repurposing safe and effective AVPR1A and AVPR2 antagonists.

Syndrome of inappropriate secretion of antidiuretic hormone following high dose rate brachytherapy for prostate cancer: a case report

Background

The syndrome of inappropriate secretion of antidiuretic hormone is a disorder characterized by the excess release of antidiuretic hormone and can result in hyponatremia. If managed inappropriately, severe hyponatremia can cause seizures, cerebral edema, and even death. There are various known causes of this inappropriate release of antidiuretic hormone, including malignancy, CNS disorders, and disturbances in the hypothalamic-pituitary-renal axis. However, reports of syndrome of inappropriate secretion of antidiuretic hormone after brachytherapy for prostate cancer are exceedingly rare.

Case presentation

We report a case of symptomatic hyponatremia secondary to the inappropriate secretion of antidiuretic hormone after prostate high-dose rate brachytherapy under general anesthesia in a patient with adenocarcinoma of the prostate.

Conclusions

In rare instances, inappropriate secretion of antidiuretic hormone can occur after high-dose rate brachytherapy for prostate cancer. The cause is likely multifactorial, involving pain or discomfort ensuing from the surgical procedure, the general anesthesia or intraoperative drugs administered. However, due to the potential severity of the side effects, timely diagnosis is crucial to ensure prompt, and effective management.

Small cell carcinoma of the bladder presenting with paraneoplastic syndrome of inappropriate antidiuretic hormone

Small cell carcinoma (SCC) of the bladder is a rare malignancy, representing less than 1% of bladder cancers diagnosed annually in the USA. In contrast to SCC of the lung, paraneoplastic syndromes are rarely documented in cases of extrapulmonary SCCs, particularly those of genitourinary origin. We present a case of SCC of the bladder presenting with paraneoplastic syndrome of inappropriate antidiuretic hormone, which resolved after treatment with sequential chemoradiation.

[SMALL CELL PROSTATE CANCER PRODUCING SYNDROME OF INAPPROPRIATE SECRETION OF ANTIDIURETIC HORMONE; A CASE REPORT]

A 73-year-old man with progressive prostate cancer visited our hospital after prostate biopsy performed at another hospital. His serum PSA level was 29.02 ng/ml. CT revealed invasion of the bladder, bilateral ureters, and rectum. Otherwise, there was no evidence of metastasis. Pathological findings showed a poorly differentiated adenocarcinoma (Gleason score 4+5) and small cell carcinoma component. Two months after administering combined androgen blockade therapy, he was admitted due to severe hyponatremia caused by the inappropriate secretion of antidiuretic hormone. Furthermore, CT revealed right ureter metastasis, although the PSA levels remained low. Therefore, the patient was put on fluid restriction and sodium administration. After the patient recovered from hyponatremia, chemotherapy, including VP-16 and CDDP, was initiated. However, CT after two chemotherapy cycles revealed disease progression, with multiple bone metastases. Second-line chemotherapy, including CPT-11 and CDDP, was less effective, and the patient died 9 months after the diagnosis.