Prostate
Focal ablation vs IMRT has no randomised comparison; this matched SEER-Medicare cohort is the current substitute, with all the confounding-by-indication that implies.
Focal Ablation vs IMRT Toxicity (SEER-Medicare)
ForLocalized prostate cancer, fee-for-service Medicare, mean age ~73
TL;DRGI toxicity favored focal therapy at 24mo (11.0% vs 21.5%, OR 0.45) but GU toxicity favored IMRT (41.7% vs 29.3%, OR 1.69).
The GI advantage rests on diagnosis claims alone: procedure-code-only GI events were too few to report and not significantly different, while the GU excess with FT was concrete (incontinence therapy 17.4% vs 7.5%). For an RT reader counseling an older man weighing ablation, that asymmetry is the point.
In an older man with localized prostate cancer choosing between focal ablation and IMRT, this supports counseling that the tradeoff runs GU-for-GI rather than uniformly lower toxicity with ablation; it does not extend to SBRT or proton patients, who were excluded.
The IMRT comparator is a 2010-2017, ≥20-fraction cohort with SBRT, protons and rectal hydrogel excluded, so the GI toxicity attributed to radiation predates spacer-era rectal sparing. That caps how much of this GI gap should carry into a current consent conversation, while the GU result (incontinence therapy 17.4% vs 7.5% favoring IMRT) transfers intact.
For ablation, the toxicity cost is concrete and periurethral: incontinence therapy 17.4% vs 7.5% and erectile dysfunction 18.2% vs 13.1%, both P<.01. The offsetting GI advantage collapsed in the procedure-only analysis, so the low-morbidity premise for cryotherapy and laser ablation in older men is weaker than the headline suggests.
10 details 5 trials watching
Retrospective SEER-Medicare claims analysis of localized prostate cancer diagnosed 2010-2017. 797 focal therapy patients Mahalanobis matched 2:1 to 1,594 IMRT patients on demographics, Medicaid eligibility, comorbidity, flu vaccination, primary care access, year, cancer characteristics and ADT. Logistic regression at 6, 12 and 24 months.
Fee-for-service Medicare beneficiaries with localized PCa as first and only cancer, continuously enrolled parts A and B from 12 months pre-diagnosis through 24 months post-treatment. New York, Idaho and Massachusetts registries excluded for missing AJCC staging. Patients who died within 24 months of treatment were excluded.
IMRT defined as external beam with no surgery plus ≥20 IMRT fractions and an IMRT planning code; a gap of ≥30 days between radiation dates counted as a separate course. SBRT and proton patients were excluded, as were patients with rectal hydrogel spacer, so the IMRT arm is conventional fractionation without a rectal spacer.
Presence of claims indicative of a GI or GU complication within 6, 12 and 24 months of treatment, assessed both as combined diagnosis and procedure codes and as procedure codes only. No patient-reported outcomes and no graded toxicity scale.
Direction reversed by organ system: GI favored focal therapy from 12 months onward, GU favored IMRT at every window measured. The 0-6 month GI comparison was null (OR 1.06, P=.81).
| Toxicity / window | FT | IMRT | OR (95% CI) |
|---|---|---|---|
| GI 0-6 mo | 3.6% | 3.5% | 1.06 (0.67-1.67), P=.81 |
| GI 0-12 mo | 6.2% | 9.5% | 0.63 (0.45-0.88) |
| GI 0-24 mo | 11.0% | 21.5% | 0.45 (0.35-0.58) |
| GU 0-12 mo | 34.6% | 15.8% | 2.69 (2.21-3.28) |
| GU 0-24 mo | 41.7% | 29.3% | 1.69 (1.42-2.01) |
GU excess with focal therapy was driven by incontinence therapy (17.4% vs 7.5%) and erectile dysfunction (18.2% vs 13.1%), both P<.01. GI events with IMRT were predominantly rectal bleeding and colitis; the authors note related procedures were rare and not significantly different.
Focal therapy patients were disproportionately rural (6.4% vs 1.9%) and lower-income (51.5% vs 38.7% in the lowest two quintiles) before matching, so claim-generating behavior may differ by arm independent of toxicity. Baseline continence and erectile function were unmeasured, which matters most for the two endpoints driving the GU result.
The GI result is fragile in a specific way the abstract does not foreground: it collapses to one diagnosis subcategory and disappears in the procedure-only analysis. The GU result is the more robust half, and it runs against the premise that ablation is the lower-toxicity option.
Claims-based retrospective matching, not randomised; toxicity defined by diagnosis codes, and the GI difference vanished when restricted to procedure codes. No PROs, no baseline function.
- Does the tradeoff hold vs SBRT or spacer-era IMRT? n=184 · primary completion 2027-06 · IRE vs prostatectomy or RT, side-effect endpointn=356 · primary completion 2029-08 · focal therapy vs usual care RCT, ISUP 2/3
- Do patient-reported outcomes track the claims-based GU signal? n=300 · primary completion 2030-12 · prospective validated urinary/sexual PROs after HIFUn=200 · primary completion 2032-03 · questionnaire outcomes across HIFU, cryo, laser, IRE
- Do HIFU and RFA carry the same GU profile as cryo/laser? n=354 · primary completion 2028-12 · HIFU hemi-ablation, continence + toxicity endpoints