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Título

CLINICAL CASE OF A PATIENT WITH CASTRATION RESISTANT PROSTATE CANCER AND UNILATERAL TESTIS METASTASIS DIAGNOSED BY GALLIUM-68 PROSTATE-SPECIFIC MEMBRANE ANTIGEN POSITRON EMISSION TOMOGRAPHY.

Introdução, Material, Método, Resultados, Discussão e Conclusões

Case Report

A 67-year-old man was diagnosed with prostate cancer in 2015. He underwent radical prostatectomy. The pathological stage was pT3bN0, Gleason score 9 (4 + 5). The initial prostate specific antigen level (PSA) was 4ng/ml.
After ten months, a biochemical recurrence was seen and re-staging exams were negative. He received rescue radiation in the prostate bed and androgen deprivation therapy with 10.8mg goserelin for 2 years.
The patient developed a biochemical recurrence six months later and he received continuous androgen deprivation therapy. In October 2019 the PSA level rose to 1.9ng/ml, testosterone was in castration level. Gallium-68 Prostate-specific Membrane Antigen Positron Emission Tomography (68Ga-PSMA PET) revealed a solitary nodular lesion with 3.0 x 2.0 cm in the left testis, SUV max 14,1 (figure 1). A unilateral orchiectomy was performed and histopathology confirmed metastatic prostate adenocarcinoma. The PSA level had dropped after surgery to 0,01ng/dl. Currently, the patient is still disease free without hormonal therapy.

Discussion:

The prostate cancer is the second most incident cancer in men worldwide, accounting for 13.5% of cases [1]. In Brazil, according to the National Cancer Institute, it is the most common cancer in men and 65,840 new cases are estimated for 2020 [2].
More than 50% of patients with high-risk disease experience biochemical recurrence [3]. In this setting, an extensive body of research has shown that the sensitivity of 68Ga-PSMA PET is better than that of conventional imaging and its correlation with PSA levels is well established. Perera et al identified the most frequent recurrence sites by 68Ga-PET PSMA: pelvic lymph nodes in 38%, prostate bed in 28% and bone in 22% [4].
Testicular metastases are uncommon and usually an incidental finding during therapeutic orchiectomy or at autopsy [5]. It is estimated an incidence of 0.93% of metastasis from solid tumors to the testes [6,7]. As far as we know, there are only three other published cases of prostate cancer patients with isolated testicular metastasis identified using 68Ga-PET PSMA [8,9,10].

Final comments:

68Ga-PSMA PET has been an important tool in the prostate cancer care. As in the case, it allows earlier detection of oligometastatic disease, often leading to change in management. In the present case, quality of life might have improved but patient outcome data of 68Ga-PSMA PET in prostate cancer are still missing.

Palavras Chave

prostate cancer, 68Ga-prostate-specific membrane antigen, testicular metastasis.