We have seen that there are many unanswered questions about focal thermal ablation (see this link), among them are:
- Is Index Tumor Theory valid?
- Can foci of cancer be precisely targeted using current imaging methods?
- Does thermal ablation completely ablate the cancer in the ablation zone?
- Will the Heat Sink Effect and biochemical protective mechanisms (e.g., heat shock proteins) always cause sub-lethal killing?
- Is toxicity and damage to organs at risk any better than radical (whole gland) radiation?
- How do the high "re-do" rates affect toxicity and costs?
- How do we track success?
- What are the best salvage therapies?
- Can it extend the time on active surveillance?
- What are the intra-operative risks?
- What is the learning curve like for therapists?
- Is it worth the cost?
- 15% were low volume GS 3+3 (cancer in ≤2 cores, <50% in any core)
- 23% were high-volume GS 3+3
- 60% were GS 3+4
- 3% were GS> 3+4
- 94% were T1c or T2a
- Median PSA=6.3
- 67% were intermediate risk (predominantly favorable)
- 33% were low-risk
- Median prostate volume was 40 cc.
- prophylactic antibiotics
- general anesthesia
- transurethral US heating wand
- pelvic tissue at apex avoided to avoid incontinence
- endorectal cooling device
- 243 minutes (4 hours), start to finish
- suprapubic catheter (17 days)
- Acute (immediate) Grade 2:
- erectile dysfunction (29%)
- UTI (25%)
- bladder spasm (10%)
- painful urination (10%)
- urinary retension (8%)
- pain (7%)
- incontinence (6%)
- epidydimitis (5%)
- Acute (immediate) Grade 3 (severe, requiring intervention):
- infection (4%)
- urethral stricture (2%)
- urinary retention (1.7%)
- urethral calculus and pain (1%)
- urinoma (1%)
- long-lasting Grade 2 adverse events:
- erectile dysfunction (23%)
- incontinence (3%)
- recurrent infections (2%)
- Sexual domain: 32%/ 1%
- ED on IIEF-15 questionnaire: 35%/6%
- 75% of previously potent men returned to erections sufficient for penetration with only ED meds.
- Urinary incontinence:14%/7%
- Urinary irritation/obstruction: 8%/5%
- Bowel domain: 5%/2%
Oncologic Outcomes (at 12 months):
- 35% had residual cancer at biopsy
- 24% among low volume GS 6
- 38% among high volume GS 6
- 37% among GS 3+4
- Median PSA reduced to 0.5 ng/ml
- Median prostate volume reduced to 2.8 cc
- PIRADS ≥3: 30%
There is little 12-month data available for other therapies, but recurrence rates almost always increase with time. There was a 2-year study of SBRT at Georgetown that may be roughly comparable:
Full-gland TULSA-PRO seems to treat PSA without eradicating the cancer (see this link). In about a third of favorable-risk patients, the cancer remained viable in spite of the thermal ablation. We see that compared to whole-gland SBRT, it is less curative, Severe (requiring intervention) acute urinary toxicity is higher with TULSA-PRO, although late-term Grade 2 urinary toxicity is lower (not severe for either therapy). Rectal toxicity is not an issue for either therapy. Potency preservation is good and about equal for both.
It is hard to see why anyone would choose TULSA-PRO over SBRT. While focal ablation may incur less toxicity, the local recurrence rate will be higher. This trial suggests that TULSA-PRO is inferior, although only a direct randomized comparison could prove that.
For an article discussing the use of focal ablation as an active surveillance "extender," see:
For an article discussing salvage focal ablation after the failure of radiation therapy, see: