Is manual prostate stimulation healthy?

The short version: the retrieved studies do not test whether manual prostate stimulation is healthy or harmful. They test diagnostic methods, drug effects, and infection mechanisms in men who already have prostate disease. That is a different question.

The evidence you provided covers prostate blood flow during sexual stimulation in women [1], nitric oxide effects on prostate muscle [2], and how infections like Trichomonas vaginalis can trigger inflammatory pathways linked to cancer cell growth [4]. None of these studies compare a group of healthy men who receive regular manual prostate stimulation to a group that does not. Without that comparison, no claim about "healthy" or "unhealthy" can be grounded in these records.

What the evidence does show is that the prostate is a hormonally and immunologically active organ. Inflammation in the prostate is common — one study found chronic prostatitis in 38% of men with elevated PSA who underwent biopsy [3]. Another study showed that inflammatory mediators from infected prostate cells can promote cancer cell proliferation and invasion in lab models [4]. But these are studies of diseased tissue, not of healthy tissue subjected to manual stimulation.

The question is answerable in principle: a well-designed study would compare rates of prostatitis, urinary symptoms, PSA changes, and sexual function between men who practice regular manual prostate stimulation and those who do not, over years. That study has not been retrieved here. Without it, the honest answer is that the evidence does not exist to call it healthy or unhealthy.

My call: the evidence does not answer the question. Confidence: not clear — the retrieval found no study that tested the practice in healthy men.