TRT and the Myths That Took Decades to Correct: Cardiovascular Risk, Prostate Cancer, and What the Data Actually Shows

For most of the last two decades, the standard medical teaching was that testosterone therapy carried real cardiovascular and prostate cancer risk — a caution baked into how physicians were trained and how patients were counseled. That caution shaped an entire generation of clinical practice. The research that's accumulated since then, including one of the largest randomized trials ever run on the subject, tells a genuinely different story: in both cases, the actual risk factor may be low testosterone itself, not the therapy used to correct it. Myth #1: TRT Causes Cardiovascular Events The fear here has real origins — some earlier observational studies did suggest a possible increase in cardiovascular events with testosterone therapy, which is part of why the caution became so entrenched. But the question finally got a definitive, large-scale answer with the TRAVERSE trial, a large randomized, placebo-controlled study specifically designed to resolve this question. According to PubMed, a position statement from the European Expert Panel for Testosterone Research synthesizing TRAVERSE and the broader trial evidence concluded that testosterone therapy does not significantly increase the risk of major adverse cardiovascular events, aligning with earlier meta-analyses and with recent FDA label changes removing cardiovascular warnings from testosterone product labeling ([Zitzmann et al., Andrology, 2025, PMID: 40372318](https://doi.org/10.1111/andr.70062)). Here's the more interesting part: the research increasingly points the other direction. According to PubMed, a meta-analysis pooling 37 observational studies covering more than 43,000 subjects found that low endogenous testosterone at baseline predicted both overall mortality and cardiovascular mortality specifically, with cardiovascular mortality risk roughly 54% higher in men with low testosterone compared to those with higher levels ([Corona et al., Journal of Sexual Medicine, 2018, PMID: 30145097](https://doi.org/10.1016/j.jsxm.2018.06.012)). The authors describe low testosterone as a marker — and possibly a contributor to — cardiovascular risk, essentially the inverse of the original fear. Low T isn't a benign finding to shrug off; the data suggests it's associated with worse cardiovascular outcomes, not better ones. Myth #2: TRT Causes Prostate Cancer This fear traces back to old, and it turns out overly simplistic, biology: prostate cancer cells are known to respond to androgens, so the logical (but ultimately wrong) leap was that more testosterone must mean more prostate cancer growth. This assumption shaped clinical caution for decades, including the practice of withholding testosterone therapy from men with any prostate cancer history at all. According to PubMed, a comprehensive meta-analysis reviewing both prospective cohort studies on endogenous testosterone levels and placebo-controlled randomized trials of testosterone therapy found the summary relative risk of prostate cancer for a meaningful increase in testosterone was essentially 1.0 (no effect), and across 11 TRT trials specifically studying prostate cancer as an adverse outcome, the risk was actually lower in the treatment group, though not statistically significantly so ([Boyle et al., BJU International, 2016, PMID: 26779889](https://doi.org/10.1111/bju.13417)). The same analysis found no meaningful difference in PSA levels between men on TRT and those on placebo. The authors' direct conclusion: prostate cancer appears to be unrelated to endogenous testosterone levels, and TRT does not appear to increase PSA or prostate cancer risk. This lines up with what's sometimes called the saturation model in urology research — the idea that prostate androgen receptors become saturated at relatively low testosterone concentrations, meaning that once you're above a fairly modest threshold, additional testosterone doesn't have more room to stimulate additional growth the way the old linear model assumed. Other TRT Myths Worth Addressing A few other persistent claims deserve a quick, honest look: "TRT permanently destroys your fertility." As covered in more detail in our companion article on TRT and fertility, this isn't accurate — TRT does suppress natural sperm production in most men while on it, but research on combined hCG/FSH therapy shows fertility can often be restored, and men can even maintain fertility while staying on TRT with the right concurrent approach. Suppression isn't the same as permanent destruction. "High hematocrit from TRT is an automatic emergency requiring you to donate blood constantly." As covered in our article on hematocrit and TRT, this is more nuanced than gym culture treats it — hydration status affects the accuracy of the reading, and recent research has actually begun questioning whether reflexive phlebotomy is even the right response, given theoretical concerns about iron depletion recreating the same problem. "Natural testosterone boosters work as well as TRT." This one doesn't hold up under scrutiny of what's actually in most over-the-counter "test boosters" — legitimate levers like sleep, resistance training, and body composition (covered in our article on natural ways to support testosterone) have real, measurable effects, but they operate on a fundamentally smaller scale than restoring genuinely low testosterone to a normal physiological range through actual therapy. Why the Old Fears Persisted So Long It's worth understanding why medicine got this wrong for so long rather than just noting that it did. Much of the original caution came from smaller observational studies, shorter follow-up periods, and reasoning from mechanism (androgens can theoretically fuel androgen-sensitive tissue) rather than from large randomized outcome data. That's not a unique failure specific to TRT — it's a recurring pattern in medicine when a plausible-sounding mechanistic story gets treated as settled fact before the definitive long-term trials actually exist. TRAVERSE and the meta-analyses above represent exactly the kind of large-scale, long-term evidence that was missing for years, and the field's guidance is now visibly updating in response — including the FDA's own 2025 removal of cardiovascular warning language from testosterone product labels. The Bottom Line The historical fear that testosterone therapy causes heart attacks and prostate cancer doesn't hold up against the largest and most rigorous data now available — if anything, the evidence increasingly points toward low testosterone itself being the more concerning marker for cardiovascular risk, and shows no meaningful relationship between testosterone levels and prostate cancer development. That doesn't mean TRT is risk-free or appropriate for everyone without individualized evaluation — but the specific fears that shaped a generation of overly cautious prescribing appear to have been aimed at the wrong target.