Rate of seeding cancer via transperineal biopsy for prostate

The retrieved evidence does not contain a single study that measures the rate of needle-tract seeding after transperineal prostate biopsy.

The records you supplied cover infection rates, needle placement accuracy, cost, cancer detection, and complications like bleeding and urinary retention [1][2][3][4]. None of them tracked whether cancer cells were deposited along the needle path and grew into a new tumor. The closest records come from hepatocellular carcinoma biopsies, where needle-tract implantation occurred in about 0.8% of percutaneous biopsies and 1.2% of radiofrequency ablation procedures [5]. But those are liver tumors, not prostate, and the biopsy route is different.

The mechanism that makes seeding possible is real. A biopsy needle passes through tissue that may contain cancer cells, and those cells can be dragged back along the tract. For prostate cancer, the concern is that the transperineal route passes through the perineum and the pelvic floor before reaching the prostate, creating a longer tract than the transrectal route. If cells are deposited anywhere along that path, they could grow into a palpable or image-visible nodule. The liver-biopsy literature shows that when seeding happens, it typically appears within 5 to 13 months and the nodules are usually small, under 2 cm [5].

But without a single study in this retrieval that actually looked for seeding after transperineal prostate biopsy, the rate is simply unknown. The absence is not proof of safety. It is a gap that the literature has not filled.

My call: the rate of needle-tract seeding after transperineal prostate biopsy has not been measured in any study in this retrieval. The mechanism exists, but no number can be given. Confidence: low, because the evidence does not address the question.