Radiotherapy in the Definitive Management of Oligometastatic Prostate Cancer

[snoraste]

"TAKE-HOME MESSAGE

The authors of this retrospective study from a single tertiary care institution described their experience with metastasis-directed radiotherapy in oligometastatic prostate cancer, evaluating biochemical progression-free survival (PFS) and time to next intervention in 156 patients. The cumulative incidence of local failure was 7.4% at 24 months. Median biochemical PFS was 12.9 months, and the median time to next intervention, including repeat radiotherapy, was 21.6 months. Median biochemical PFS (17.2 months vs 7.2 months) and cumulative incidence of local failure at 24 months (4.8% vs 12.1%) were favorable in patients with hormone-sensitive oligometastatic prostate cancer compared with castrate-resistant disease. Multivariate analysis showed peri-radiotherapy androgen-deprivation therapy, lower gross tumor volume, and hormone-sensitive disease to be associated with prolonged biochemical PFS, leading the authors to suggest that the optimal time for intervention may be with lower-volume disease. Treatment was well-tolerated.

This study provides additional support to the existing literature of radiotherapy in this setting; however, prospective studies are needed."

practiceupdate.com/C/88174/...

[Tall_Allen]

It shows that treatment (ADT + RT) is more effective when done while one is still hormone sensitive vs after castration resistance - not very surprising or useful.

[snoraste in reply to Tall_Allen]

It's a retrospective study and subject to all the shortcomings associated with those sort of studies. HSPC vs CRPC was (perhaps) one of the trivial comparisons, assuming we all agree that treatments generally work better for HSPC cohort (I'm not entirely sure if we can generalize that, but I could be wrong). Of interest to me was Dr. Song's commentary and his references, and this at the end:

"We analyzed 28 men with HSOPCa treated with a course of peri-RT ADT (median 4.3 months) with recovery of testosterone. At median 33.5 month fup, 20 have not developed bPFS, median bPFS has not yet been reached, and 24 month bPFS was 77%."

Perhaps the info is trivial to you, but I learned a little more and I thought it worth members' time to skim thru.

[Tall_Allen in reply to snoraste]

You misunderstand the study. What would have happened to those men if they had not received that treatment?

[snoraste in reply to Tall_Allen]

I did not misunderstand. I know the limitation of this kind of studies very well. But whoever they are, and whatever their detailed clinical conditions, I'm very happy for them that it's working so well. And I think we should encourage "Oligo" cases to discuss this with their MOs to see if they will benefit.

[Tall_Allen in reply to snoraste]

How do you know it is "working so well?"

[snoraste in reply to Tall_Allen]

Like you said, and I agree, you cannot prove in this study that the cohort would not have done better under ADT or RT (or even placebo) alone. That's a known limitation of this study no doubt.

[NPfisherman]

Some people will wait for a randomized double blind study to believe this is a proven fact that SBRT is beneficial in Oligometastatic disease for APC. There are 2 gentlemen here who did over a year of Z/P +ADT and SBRT to their mets--one had one lesion on PSMA scan and one had 3. They are on ADT vacation and the one gentleman has an MO at Dana Farber who told him that he may go undetectable for many years off ADT.

The issue for most people that come here is this.... Can you wait for a Phase 3 randomized double blind study to decide to do SBRT if you are Oligometastatic?? My answer was no....and I did SBRT...

Each person has to decide that question who is in our situation. Some individuals here have no cancer and do not have this problem... Some individuals have been cured by SBRT, but still see no value in SBRT for Oligometastatic Disease...

Do not waste your time discussing this with them. The Phase 3 will be done in a few years... I look at the 2 guys on ADT vacation, my own results so far, various studies like Dr Heron's at UPMC and I believe it will be beneficial and not just in PCa, but other cancers to increase OS and allow additional time for QOL...

Thanks for posting...

Don Pescado

[Tall_Allen in reply to NPfisherman]

If one treats himself without adequate evidence of benefit, one is letting oneself in for potential side effects without benefit. In most cases, side effects are small, which is why I usually advocate for MDT when there are few mets. However, I don't think anyone should kid himself that there is any evidence where there is none. If you wish to do that for yourself- that is certainly your decision. When you seek to imply there is evidence where there is none, that is misleading to patients. If done out of ignorance, that is understandable. If done intentionally, that is unconcionable.

[NPfisherman in reply to Tall_Allen]

There is no Phase 3 results for SBRT and Oligometastatic PCa.... I have not seen any trials showing a lack of benefit from Phase 2... Dr Heron's trial for instance, although that trial had limited PCa patients..

Do you have any recent trial results showing a lack of benefit using SBRT in Oligometastatic PCa? If so, please list them..

No one is attempting to mislead anyone. As stated previously, we, who have cancer, have to make hard decisions to enter trials or do treatments that will effect our lives, and may be faced with a situation where we must weigh the evidence and decide without the benefits of a randomized double blind study...

When I spoke with my MO in August, Dr Ornstein at Cleveland Clinic, we discussed my having SBRT to my one met., and I stated that I had seen several positive studies using SBRT in Oligometastatiic dx, but nothing negative. He confirmed that statement...

As stated, everyone is their own steward on this journey and do so with the help of their MO and/or RO, etc... Safety and results, along with QOL and OS, will always be the concern for those on this journey..

Don Pescado

[Tall_Allen in reply to NPfisherman]

There are no trials showing any benefit. I do not think that SBRT of mets will make it worse. It is anyone's guess as to whether it delays progression - there is just no information yet. It is difficult making decisions under conditions of no or incomplete information. My point is that you cannot just pretend that studies say what you hope they will say.

[NPfisherman in reply to Tall_Allen]

From this study:

astro.org/ASTRO/media/ASTRO...

CONCLUSIONS:

SABR was associated with improved OS, meeting the primary endpoint of this trial,

and PFS was doubled. Toxicities were more common with SABR, with a 4.5% risk of

treatment-related death, but no decrease in QOL.

And while they did go to say:

Next steps: phase III RCTs for 1-3 and 4-10 metastatic lesions

This was a randomized trial, although not double blind. Do you believe their conclusions were incorrect, or do you feel that without a randomized double blind study there is no proof and you can not endorse it because of that issue? In essence, for you to endorse something, there must be a randomized double blind study to support that endorsement. Is that correct?

Don Pescado

[snoraste in reply to NPfisherman]

Don,

I remember seeing that report and I thought it was suggestive of a benefit. But I did not think of it as a proof for PCa benefit. My main issues with the report was with the number of PCa patients in the control arm (potentially low power stats, and type2 errors), and robustness of their model mixing all the cancer types in (based on my cursory read of the report).

I also have to say that I agree with you: stage4 patients do not have the luxury of time, and for the better of worse have to make decisions based on these types of “indications”.

[Tall_Allen in reply to NPfisherman]

Their conclusions certainly were incorrect. They committed a mathematical error:

pcnrv.blogspot.com/2019/04/...

[snoraste in reply to Tall_Allen]

There's no question about that. Robust Level-1 evidence is what settles the issue. Until then, it's the responsibility of the patient to get educated on the pros and cos (hence these dialogues), and consult with his MO(s). My main point is that patients ought to discuss these (sometimes conflicting) findings with their MOs and seek advice, and not just stand back and wait for "evidence" to start a dialogue. There are more MOs looking into variations of these therapies. Are they seeing encouraging signs? My MO thinks so. But I'm always aware that is not "evidence" in the scientific terms, but a choice.