Case report

A 64-year-old man presented with a prostate-specific antigen (PSA) elevation of 9 ng ml^-1 and a palpable lesion involving more than half of the right lobe of the prostate (cT2b). A transperineal sextant biopsy revealed adenocarcinoma with a Gleason score 3+3=6 in two-sided cores. The patient underwent brachytherapy as monotherapy with curative intent. A combined ultrasound and fluoroscopic guided transperineal permanent iodine-125 implant (Rapid Strands) was used. Fluoroscopy confirmed the correct position of seeds at the end of the procedure. One month after treatment, PSA was at 1.2 ng ml^-1, and PSA nadir (0.5 ng ml^-1) was achieved after 7 months.

Twenty-four months after brachytherapy, PSA levels increased up to 18.7 ng ml^-1. A restaging 12-core biopsy revealed adenocarcinoma (Gleason score 4+4=8) in two samples from the right peripheral portion of the prostate. Endocavitary magnetic resonance demonstrated a hypo-intense lesion of the right prostatic base. Bone scan and computed tomography scan of the abdomen and pelvis excluded lymph node, bone or systemic metastases.

To treat the local failure, the patient underwent anterograde radical prostatectomy and bilateral iliac-obturator lymph node dissection.¹ Operative time was 160 min and blood loss was 500 ml without intra- or perioperative complications. At surgery, several seeds were recognized on the right elevator muscle of the anus and on the pre-rectal fat tissue. Catheterization time was 14 days, while hospitalization was 7 days. PSA decreased to 0.6 ng ml^-1 after 1 month, and at 1-year follow up was 0.01 ng ml^-1. One month after prostatectomy, the patient was fully continent, without bowel discomfort, whereas he complained of erectile dysfunction subsequently controlled by PgE.

No hormones have been used at any time (before and after both brachytherapy and prostatectomy).

Prostatectomy specimen underwent double-blind evaluation with RX scan and whole-mount histopathology sections.

Radiology was performed in four projections (AP, CC, LL left and LL right) with acquisition on digital device and exposure time of 0.6 mA s^-1 and 77 kV, suitable for soft tissue assessment. All projections revealed a 1 2.5 1.5 cm area without any seeds in the right base of the prostate (Figure 1).

Figure 1.

RX scan of operative specimen (Projections: (a) antero-posterior, (b) craniocaudal, (c) left latero-lateral and (d) right latero-lateral). Ellipse shows an uncovered area in the right base of the gland.

Full figure and legend (147K)

Pathology demonstrated poorly differentiated acinar adenocarcinoma involving the right base of the gland and infiltrating both seminal vesicles, with perineural invasion (Figure 2). Surgical margins and lymph nodes were free of tumor. According to the 2002 TNM criteria, the pathologic stage was pT3b N0 Mx.

Figure 2.

(a) Operative specimen. (b) Whole-mount section of the radical prostatectomy specimen showing the outlined tumor area with the greatest diameter of 2.6 cm in the right base of the gland.

Full figure and legend (262K)

Discussion

Brachytherapy as monotherapy with curative intent is an effective treatment choice for clinically localized prostate cancer (cT2a), with PSA10 ng ml^-1 and bioptical Gleason score 6.² Additional parameters are life expectancy above 10 years and comorbidities contraindicating radical prostatectomy.

Biochemical failure after brachytherapy can occur in 25–50% of patients, according to different definitions of post-brachytherapy PSA failure.³ Patients with prostate cancer relapse after brachytherapy should undergo clinical restaging to decide on the feasibility of either local or systemic therapy. Biopsies after early-stage brachytherapy show post-treatment positive rates of 3–26%.^{4, 5} Furthermore, tumor recurrence is local in 72% of cases, systemic in 20% and both local and systemic in 8%.⁶

Seed misplacement (the difference between the actual and planned seed locations) can lead to a significant degradation in dose coverage of the prostate and consequently to local failure.⁷ Wrong location of seeds can be primarily due to inaccuracy in needle positioning, prostate motion during the procedure, edema or bleeding and post-implant migration.⁸ In particular, a migration amount of 6 mm can lead to a D90 reduction to 946%, with a 40% drop in tumor control probability, assuming radiosensitive tumors.⁹

In the present case, the overall probability of successful outcome (freedom from recurrence) 5 years after brachytherapy was nearly 80%, according to contemporary pretreatment nomogram.¹⁰ However, 2 years after seed implantation, the patient presented a biochemical failure, and re-biopsy with bone and computed tomography scan revealed a local recurrence of prostate cancer, without nodal, bone or systemic metastases. The complete coverage of the gland, proved by post-treatment fluoroscopy and dosimetry performed 4 weeks after implantation according to the American Brachytherapy Society guidelines,¹¹ allowed the PSA nadir to be achieved 7 months after implantation. The following PSA remission confirmed the initial correct positioning of the seeds. Subsequently, seed migration from the right base of the prostate was the main cause of tumor relapse in this area, and consequent PSA progression.

Salvage prostatectomy appears to have the greatest curative potential for locally recurrent prostate carcinoma, with a 5-year biochemical disease-free rate ranging between 55 and 69%.^{12, 13} In several experiences of post-radiation salvage prostatectomy, the organ confined rate is 20–39.5%, the seminal vesicle involvement varies from 25 to 62.5%, while the rate of surgical complication is between 0 and 19%.¹⁴ In our case, prostatectomy was carried out without intra- or postoperative complications, with only extended operative, catheterization and hospitalization times. The tumor was organ confined, surgical margins and regional lymph nodes were negative, and the postoperative decline of PSA demonstrated the efficacy of local salvage treatment.

In conclusion, this double-blind radiologic and pathologic work-up demonstrated that, in the present case, PSA recurrence occurred for seeds misplacement after a correct primary seeds positioning.

References

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