Potency-Sparing Radiation

[Atlantic77]

3+4=7 tumour(7mm) located in right apex with possible EPE.

RO has informed me that due to proximity of tumour to penile bulb, high probability of ED as the bulb will get a significant dose.

Is there any way of minimising dose to the CES (Critical Erectile Structure) without compromising oncological treatment. I have read that the distance between CES and apex can vary between 0.6mm-2.3cm. Surely with Truebeam SBRT there must be a way of precisely contouring dosage? - That would be my understanding of a beneficial quality of precision radiation therapy.

Also during RT how do they manage to spare the nerve bundles on either side of the prostate during treatment, especially in the case of possible EPE where they treat a margin outside of the prostate?

[Tall_Allen]

They don't spare the nerve bundles, but nerves are pretty much impervious to radiation. When radiation causes ED, it is because of build-up of scar tissue in blood vessels. ED meds (like Cialis) may protect blood vessels.

There is some controversy as to whether the dose to the penile bulb really causes ED:

pubmed.ncbi.nlm.nih.gov/181...

In this study they found that penile bulb doses over what would be equivalent to 9 Gy of SBRT dose were associated with ED.

ncbi.nlm.nih.gov/pmc/articl...

There is no precise correlation between dose to penile bulb and ED. It depends a lot on age, previous potency and your formation of scar tissue. They usually set a maximum dose.

They do precisely contour the radiation, but the penile bulb will still get some. Just how much is the result of individual anatomy. You can ask your RO to show you the dose-volume histogram with the penile bulb as the organ at risk. It shows the dose the penile bulb will receive.

Another option is find a brachytherapist. Considering the EPE, probably a high dose rate brachytherapy treatment would be best. It may be difficult to find such a specialist where you live. I don't know if the penile bulb sparing will be any better, though.

[Hidden in reply to Tall_Allen]

Seems like radiation induced ED involves more factors than just scar tissue and it can damage nerves leading to loss of function over time. Information like this convinced me to avoid radiation in favor of HIFU ablation.

sexhealthmatters.org/erecti....

[Tall_Allen in reply to Hidden]

That article is incorrect (Stick to peer-reviewed studies. Anyone on the internet can write anything.)

Radiation has the largest effect on rapidly growing cells (like cancer) and very little effect on slow growing cells like nerves and muscles. I won't say there is zero effect, but it is very small. This was established by J. Bergonié and L. Tribondeau in 1906 and is well known.

You may be interested in a radiation technique that preserves erectile function by sparing the pudendal artery. It is discussed here:

prostatecancer.news/2017/03...

The damage to erectile function is ultimately caused by atherosclerosis even in RP patients. When nerves are damaged by surgery, they no longer innervate erectile tissues. With lack of use, those tissues become sclerotic:

sciencedirect.com/science/a...

I don't know that HIFU is any better than radiation at preserving erectile function.

[Hidden in reply to Tall_Allen]

Well, here's some more input on the subject, peer reviewed or not:

webmd.com/prostate-cancer/q...

awaremed.com/dr-dalal-akour...

mayoclinic.org/diseases-con...

Unless you are claiming that Mayo falls under the "Anyone on the internet can write anything" category.

HIFU preserved erectile function for me. Data point of one.

[Tall_Allen in reply to Hidden]

Sources matter. Who knows who wrote any of that and if it's accurate? Sometimes there is expert opinion from organizations (like NCCN, ASTRO, ASCO or AUA), but even there there is a peer-review process. I do accept presentations to peers at the major org meetings - they have a good record for accuracy. Just like my articles, I check the sources of articles laymen write - if they don't link to source material, I ignore it, and suggest others do too.

By the way, I consider hospital and corporate sites to be highly suspect. Mainstream media often just republish press releases.

[cesces]

Make sure they use cyberknife equipment

[curtisbirch]

If you haven’t considered HDR brachy, you should definitely look into it as a strong option to any kind of beam. The treatment is directly on the affected areas and the mapping of the placement of the radiation is precise to the millimeter. I am young so quality of life was a major reason I went this route along with very high success rates for intermediate risk. I can provide you with details if you want to message me.