Advances made in prostate cancer treatment

If a colleague is twirling a handlebar moustache this month, you can probably thank Let It Grow — an international campaign that uses facial hair to raise awareness of prostate cancer during November.

Prostate cancer is the most diagnosed malignancy among North American men. Yet treatments — from surgery and radiation to hormone therapy — traditionally carry risks such as sexual dysfunction and incontinence. But researchers at U of T are breaking new ground in prevention, diagnosis and treatment.

“The thing we’re probably best known for around here is the active surveillance concept,” said Professor Laurence Klotz, chief of the division of urology at Sunnybrook Health Sciences Centre.

Pioneered by Klotz’s group at Sunnybrook, active surveillance balances early detection and aggressive monitoring of prostate cancer with delayed intervention where monitoring indicates a patient is at low risk. As more data have emerged that support active surveillance, “the whole world has come around to this way of thinking,” but Klotz encountered resistance at first.

“Many patients are diagnosed with prostate cancer whose lives are not threatened by it but more than 90 per cent of patients were being treated and the treatment has significant side effects,” Klotz said. “We set out more than 10 years ago to change that and we were a voice in the wilderness originally.

“For patients with a new cancer diagnosis, to be told they don’t need treatment when it’s a disease that can be lethal was fairly shocking. But we won the day.”

Active surveillance is not to be confused with watchful waiting, an earlier approach used by some physicians, which gave patients no opportunity for definitive local therapy. Active surveillance involves closely monitoring the biomarker prostate-specific antigen (PSA) and repeating biopsies to identify the subset of men who would benefit from radical therapy.

If a patient reaches the stage where surgery is needed, he may benefit from a new technique Klotz has developed, combining magnetic resonance imaging with thermal ablation (removal) to destroy tissue.

“You can use MRI to give you a thermal map of internal tissues that’s updated every three to five seconds,” Klotz said. “If you’re using a thermal ablation type of therapy where you’re heating tissue, the ability to do it with precision, where you heat just to a certain temperature and then stop, is huge.”

Precision is the key to success with any minimally invasive therapy, Klotz said.

“Particularly the prostate is in an area where there are a lot of critical structures around: the sphincter, the neuro-vascular bundle required for preservation of erectile function, the rectum,” he said.

Using a special ultrasound transducer placed in the urethra, the surgeon generates ultrasound waves that are absorbed by tissue. So far, about eight patients have had the procedure.

“The system waits until the area you’ve targeted is heated to a point where the cancer is destroyed and then it rotates so the whole prostate gets treated,” Klotz said. “It’s very quick — it takes about half an hour, while other techniques typically take three to four hours to do this.”

Today, the procedure is performed only on patients having their prostates removed for cancer, in hopes it will reduce the chance of finding cancer outside the prostate after surgery. “The ablation is done earlier the same day, virtually the same anesthetic,” said Klotz.

“The tissue is ablated to an area within about one millimeter of what we targeted which is phenomenal,” Klotz said. “So we’re just planning the next stage which will be to actually treat cancer, see how effectively we can image and treat cancer, followed by the removal of the prostate to prove that.

“And then the next step will be to actually use this for primary treatment. But we’re still probably about two years away from that, to where it is the only treatment patients would get.”

Klotz is also researching the role of micronutrients in the prevention of prostate cancer.

“The main things we’re interested in are capsaicin, metformin and some other anti-oxidants like lycopene,” Klotz said. “We’ve had some remarkable results in animal models and we’re just starting some human studies.”

Capsaicin — the active component of chili peppers — looks particularly promising as a prostate cancer prevention agent, Klotz said.

“I actually first got into this because we had a patient who got interested in this as a folk medicine approach,” Klotz said. “He put himself on very high doses of this hot sauce, and although things hadn’t been looking too good for him, his PSA stabilized.”

However, the capsaicin began interfering with the patient’s blood pressure medication. On the advice of his internist, the patient discontinued using capsaicin, only to see his PSA start to go up again. Curious, Klotz used high-performance liquid chromatography to analyze the sauce the patient had used.

“It basically consisted of capsaicin and lycopene, so now we’re studying that in these animal models and tissue culture and it looks very promising.”