Laser Ablation for Prostate Cancer: Largest Data Set

Minimal Urinary, Erectile Problems, Say Investigators

Nick Mulcahy

May 01, 2019

Focal laser ablation (FLA) for prostate cancer shows "promising early oncologic results" and "acceptable morbidity" in men with low- to intermediate-risk prostate cancer, concludes a new single-center study of the experimental treatment method.

However, outcomes from this series of 120 patients, which is the largest data set published to date, indicate that nearly 20% of the men needed some form of re-treatment after one year.

Also, an expert not involved with the study, who congratulated the authors for collecting and publishing data, believes the study has important limitations.

The new study appeared in the March issue of the Journal of Vascular and Interventional Radiology 

"There's a huge untapped population of men who don't want to undergo surgery — this gives them an alternative," lead author Eric Walser, MD, an interventional radiologist at the University of Texas Medical Branch in Galveston, told Medscape Medical News.

Walser is one of the first practitioners in the US to use FLA to treat prostate cancer.

With FLA, the prostate is accessed via the rectum. The laser fiber and rectal probe are guided to the tumors using an interventional magnetic resonance (MR) imaging system.

The investigators report that, 1 year after FLA, study patients had "no significant changes in quality of life," and 83% were free from re-treatment.

However, the remaining 17% (20 of 120 patients) required re-ablation or some other treatment within 1 year after FLA, following an abnormal follow-up MRI or prostate-specific antigen (PSA) and subsequent biopsy confirming cancer.

Walser predicts that the rate of cancer recurrence will drop to around 10% because his team modified its technique.

Initially, FLA consisted of "very focused ablations," said Walser. However, eventually, during the 3-year study period, the area of ablated tissue surrounding the tumor was expanded in an effort to reduce the risk of recurrence; there was preliminary evidence suggesting these "hemiablations" were more effective, said the authors.

Also, sexual and urinary function, which are the great bugaboos of prostate cancer treatment, did not significantly change in the cohort after treatment with FLA, said the authors. Median follow-up was 34 months.

"I have tremendous admiration for Dr Walser and their program for collecting data for this new, innovative, and potentially exciting technology," said Scott Eggener, MD, of the University of Chicago, a urologist who works with an interventional radiologist and has participated in two other clinical trials of FLA.

However, Eggener believes patient follow-up in the new study, which routinely included only MRI and PSA, was insufficient. "We know from our own studies [of FLA at University of Chicago] that these can be unreliable after laser ablation," he told Medscape Medical News.

"We've seen patients where the PSA and MRI looked good but they still had meaningful cancer on biopsy," he added.

Studies of ablative technologies for prostate cancer "must include biopsy follow-up," Eggener emphasized.

In the current study, only 44 of the 120 men had a follow-up biopsy (prompted by abnormal PSA or MRI), pointed out Eggener. "So you can't fully understand how well laser ablation worked or didn't work."

More About ED and Urinary Function

All study patients were treated between 2013 and 2017, with a median patient age of 64 years.

Pre-treatment biopsy Gleason scores were 3 + 3 = 6 in 30.8% of patients;
3 + 4 = 7 in 46.7% of patients; and 4 + 3 = 7 in 22.5% of patients.

Most of the men (74.2%) had a pre-treatment clinical stage of cT1c. Nearly all of them (99%) had either one or two tumor sites on their gland.  

This is an admirable mix of patients, suggested Eggener. "I give Dr Walser credit that two thirds of the patients he has treated have Gleason score seven or higher cancers, because most clinicians would agree that it [FLA] should not be used routinely on people with lower grade cancers," he said

The median PSA level of patients prior to treatment was 6.05 ng/mL and decreased to 3.25 ng/mL at 12 months post-treatment (P < .001).

Tumor diameter above the median (odds ratio [OR] = 3.36) was the lone statistically significant predictor for a post-treatment positive MRI — and thus the need for biopsy and the possibility of a confirmed recurrence.

Walser said that the patients in this study were overall highly educated and affluent. They tended to be white-collar professionals such as engineers and doctors who search online for alternative treatments to prostatectomy. Other alternative treatments including high intensity ultrasound (HIFU) and microwave ablation also appeal to this type of patient, he said.

Currently, FLA is not reimbursed by insurance or Medicare. Walser's patients come via his Internet marketing or are self-referred.

Each case in the cohort required an investigational review board (IRB) approval at his institution, said Walser.

"My typical patient is a guy in his 40s whose PSA went up over 4 [the lower limit of suspicion] and then finds out he has low-risk prostate cancer. And they are terrified because they may have a dad or older brother who's been treated for prostate cancer and is still wearing diapers two years after surgery or can't get an erection," Walser said.

"These guys are saying ‘I'm too young for that.' " Incontinence is the biggest fear, he added.

In the study, quality-of-life surveys (International Prostate Symptom Score [IPSS] and Sexual Health Inventory for Men [SHIM]) were administered at the follow-up visits.There was no difference between functional scores before and after ablation, say the authors.

The complication of erectile dysfunction was reported as grade 1 in 5% of the men and grade 2 in 2.5%. Urinary retention was reported as grade 1 in 4.1% of the men and grade 2 in 0.8%.

"We can destroy the tumor without damaging the nerves that control erection and urinary function," said Walser.

In their discussion section, the study authors said FLA looks good compared to surgery and radiation for these two important outcomes. "Given recent data showing significant decrease in genitourinary function and quality of life up to 3 years after surgery or radiotherapy, stability in these areas for up to 1 year following FLA in the present study compares well with other definitive treatments," they write.

In his comments to Medscape Medical News, University of Chicago's Eggener focused on the erectile dysfunction data, suggesting they are unusual.

"The reported ED rates are impressively low, given that most men had hemiablations. Historically, any technology that uses hemiablation has significantly higher erectile dysfunction," he said.

Historically, any technology that uses hemiablation has significantly higher erectile dysfunction. Dr Scott Eggener

The findings are encouraging but "absolutely" need to be replicated and validated in additional studies, he added. 

The most common complication in the new study was grade 1 hematuria (7.4%), which resolved in all men.

Notably, two men developed rectourethral fistulas early in this FLA program. Both fistulas resolved with prolonged Foley catheterization. "Although this was a serious complication, all of the fistulas healed spontaneously with urinary diversion and urethral rest for 4–6 weeks," write the study authors. Subsequently, saline/lidocaine solution was injected to create a space between the rectum and prostate in order to minimize fistula formation.

The study authors acknowledge their results are subject to selection bias. They also point out that all study patients were counseled regarding active surveillance and other definitive treatment options.

The study was supported by the Institute for Translational Sciences at the University of Texas Medical Branch and partially supported by other institutions, including the National Cancer Institute. Walser has disclosed no relevant financial relationships. Eggener has no financial relationships related to FLA but works with other ablative therapy companies as a consultant.

J Vasc Interv Radiol. Published online March 2019. Full text

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