There was a time when proton beam therapy seemed to be the “Holy Grail” of prostate cancer (PCa) treatments. In 1990, the Loma Linda University Medical Center became the world’s first hospital-based proton beam treatment center, making this treatment available to all cancer patients. A decade later, the New York Times reported that proton beam had now joined the ranks of other standard PCa treatment options. Patients everywhere were heartened at the news.

What’s so special about proton beam radiation? Well, protons are subatomic particles that have a positive charge. They have about 1,835 times the mass of electrons, and because of this they have less “scatter” effect. This means more accurate delivery, with less radiation emission on exiting the tumor. Also, proton radiation is very short-lived. Because of these features, patients report fewer side effects from treatment, and it is believed that there is less risk of organ damage or secondary cancers in neighboring areas. For prostate cancer patients, this translates to great expectations of higher success rates and lower side effect rates. However, in some respects proton beam is not totally special.

Radiation is not an instant treatment

Radiation is radiation. It does not kill cancer immediately, but rather interferes with the cancer cell’s ability to reproduce itself. While healthy cells are hardier and less prone to radiation’s effect, the mutated cancer cells gradually die off. Radiation can only do its job when there is prolonged exposure. It must keep the pressure on. If there’s not enough radiation, or the cancer is particularly aggressive, there’s a chance some cells will survive and “come back angry.” For this reason, beam radiation treatments must continue daily over several weeks.

This principle applies equally to proton beam treatment. It does not destroy the cancer right away. However, as I mentioned above, it has an advantage over other kinds of radiation by reducing collateral damage, thanks to less scatter.

A treatment struggling to survive?

If a PCa patient’s disease and lifestyle mean he’s not a good candidate for surgery or ablation, radiation may be the most appropriate choice. In this case, proton beam may be most appealing. However, he may have a hard time locating a center close to him, because proton beam centers are losing ground.

The initial enthusiasm for treating PCa with proton beam has cooled, largely for economic—not clinical—reasons. Proton beam radiation requires a huge investment in terms of buildings and equipment. This means many people must be treated in order to help meet costs. Many of the tumors for which proton beam is a great choice, such as pediatric tumors where less radiation scatter is extremely important, are actually relatively rare. So proton centers need all the prostate cases they can get.

However, from the standpoint of medical insurers, this is not such a good deal. Why should they cover the extra cost—up to tens of thousands of dollars—if proton results are no better? There’s little published evidence that the success rate for proton beam is superior to IMRT or SBRT—nor is there a compelling body of evidence that there are significantly fewer short- and long-term side effects. If this is the case, it makes sense that insurers are increasingly resistant to reimbursing for it. This poses a big financial hurdle for proton centers.

Another problem is scarcity. There are fewer patients than originally planned for. According to one news story, “Patient demand for the technology has been much lower than anticipated in some centers, and several centers have been grappling with financial losses or have missed financial targets…” The story goes on to cite centers in California, Indiana, and Virginia that have either closed or are deeply in debt.

I think the issue of shrinking patient demand is particularly interesting. Why is this happening?  For one thing, there’s always something a little scary about undergoing radiation, almost like a psychological fear that was perhaps implanted during the Cold War that has never quite gone away. Also, the use of Active Surveillance for low risk PCa patients has risen steeply for many reasons—though it too can cause an undercurrent of anxiety (see my blog on the subject). Finally, the idea of focal therapy like our Focal Laser Ablation continues to gain traction; PCa patients like the ability to control cancer with minimal-to-no side effects, knowing future treatment options are available.

Proton beam radiation is undoubtedly a great choice for certain cancers, such as brain, lung, central nervous system, and cancers that can’t be surgically removed. It is also a good choice for localized prostate cancers for which surgery or ablation is not recommended or feasible. However, if insurance won’t cover it for PCa, or centers aren’t available, hopefully it won’t have lost so much ground that those who truly need it will lose access to it altogether.

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

References

[i]Bryant CM, Henderson RH, Nichols RC, Mendenhall WM et al. Consensus Statement on Proton Therapy for Prostate Cancer. Int J Part Ther. 2021 Apr 12;8(2):1-16. [ii] Mendenhall WM, Brooks ED, Smith S, Morris CG et al. Insurance Approval for Definitive Proton Therapy for Prostate Cancer. Int J Part Ther. 2021 Jul 27;8(3):36-42.