In a sham-controlled trial, vaginal laser added nothing for breast cancer survivors

Breast cancer survivors on aromatase inhibitors face a particular bind. The drugs cut oestrogen to the bone to keep cancer from returning, and in doing so they bring on genitourinary syndrome of menopause — vaginal dryness, burning, pain with sex — often more severely than natural menopause does. Because oestrogen is the thing their treatment is designed to suppress, the usual hormonal creams are off the table or used only with caution. That gap has made energy devices such as fractional carbon dioxide (CO2) laser an attractive, heavily marketed option. A trial published October 15 in JAMA Network Open tested whether the laser actually earns its place [s1].

A real laser against a fake one

The study is a secondary analysis of a single-centre, double-blind, sham-controlled randomised trial run at a tertiary academic hospital in Spain (ClinicalTrials.gov, NCT04619485) [s1][s2]. Researchers enrolled breast cancer survivors who had genitourinary syndrome of menopause and painful sex while taking aromatase inhibitors, recruiting them between October 30, 2020, and September 1, 2021, and following them for 12 months [s1]. Participants were randomly assigned to five monthly sessions of CO2 laser therapy or to an identical-feeling sham laser that delivered no therapeutic energy [s1].

Crucially, everyone — both arms — also received first-line non-hormonal therapy, meaning vaginal moisturisers and vibrators [s1]. That design matters: it means the trial was not asking "does laser work?" so much as "does laser add anything on top of the simple, cheap care every patient should already be getting?" The primary outcome was the difference between groups in how much the Female Sexual Function Index (FSFI) score changed [s1].

No separation between the arms

Of 84 women randomised (mean age 53.8 years), 67 completed the 12-month follow-up — 32 in the laser group and 35 in the sham group [s1]. On the main measure, the two groups were indistinguishable: the between-group difference in FSFI change was −0.69 (95% CI, −3.58 to 2.20; P = .64) [s1]. No secondary outcome favoured the laser either [s1].

What the trial did find was that both groups got better. Across the full sample, FSFI scores rose from 18.9 to 23.0 over the year (mean difference 4.5; 95% CI, 3.1–5.9; P < .001) [s1]. Pain with sex eased (mean difference −3.7; 95% CI, −4.4 to −3.0; P < .001), body-image scores improved (−3.9; 95% CI, −5.1 to −2.8; P < .001), and the Vaginal Health Index climbed (4.2; 95% CI, 3.1–5.2; P < .001) [s1]. The share of women sexually active rose, with 57 of 67 (85.1%) reporting sexual activity at the end (odds ratio 2.35; 95% CI, 1.23–4.50; P = .009) [s1]. Even objective tissue measures shifted: vaginal pH fell (−0.5; 95% CI, −0.8 to −0.2; P < .001) and the vaginal maturation index rose by 19.0 percentage points (95% CI, 13.4–24.5; P < .001) [s1].

Why the improvement is not evidence for the laser

It is tempting to read that broad improvement as a win for the device. The trial's design is what guards against that mistake. Because the sham group improved just as much as the laser group, the gains cannot be attributed to the laser [s1]. The authors conclude that the improvements in both arms "likely reflected" adherence to the non-hormonal first-line therapy, the act of being in a trial, or other contextual factors rather than any effect of the laser itself [s1]. Adherence to that first-line therapy was similar between the groups [s1].

This is a familiar pattern for vaginal energy devices. Open-label studies and before-and-after series routinely show big improvements, but the handful of trials that include a convincing sham arm tend to find the device does no better than the placebo procedure. GSM symptoms respond to attention, to consistent moisturiser use, and to the regression-to-the-mean that follows seeking care at a low point — none of which require an expensive laser.

What it means for patients

The practical takeaway is narrow but useful. For breast cancer survivors on aromatase inhibitors, the trial supports starting with non-hormonal first-line care — moisturisers, lubricants, and devices that support sexual activity — and gives no evidence that adding CO2 laser improves sexual or vaginal health at a year [s1]. On safety, no severe adverse effects occurred in either group [s1].

The authors are careful about the limits of their own work: this was a single centre, the sample was modest, and it was a secondary analysis [s1]. They argue that high-quality sham-controlled trials "remain essential" before laser therapy is adopted as routine care for this group [s1] — a pointed caution given how widely the devices are already offered and paid for out of pocket.