Despite recent advances in the treatment of men with prostate cancer, radiation therapy remains a staple in multiple settings of this malignancy, said Holger L. Gieschen, MD.

Patients ranging from low- to high-risk disease can be treated with radiation; however, prostatectomy is a competing modality. While high-risk patients are often treated with surgery, they can also benefit from radiation therapy, noted Gieschen, an assistant professor at the University of Tennessee Health Science Center and a radiation oncologist at West Cancer Center.

“There is a lot of confusion about what we actually do in terms of treatment modalities,” he said. “A lot of patients who are candidates for one modality are candidates for others.”

In an interview during the 2018 OncLive® State of the Science Summit™ on Genitourinary Cancers, Gieschen discussed the role of radiation therapy in prostate cancer and ongoing efforts to further refine this strategy.

OncLive: How do you determine patient selection for radiation therapy?
Gieschen: There are a number of patients who are appropriate for radiation oncology. We actually treat patients from the low-risk to the very high-risk groups. Of course, in prostate cancer, there are competing modalities, such as surgery. Besides definitive treatment of prostate cancer, we also use radiation for palliative approaches in metastatic disease. We use it in the salvage setting when patients have rising prostate specific antigen (PSA) levels after surgery.

What are the differences in administering radiation therapy in the definitive setting versus the palliative setting?
In the palliative setting, it is usually a short course of dosing that is driven toward reducing pain and improving the quality of life. In the curative setting, the courses are longer, and the aim is obviously to cure the cancer and for the patient to be free of disease afterwards. Sometimes, radiation can be combined with other modalities.

What are the standard approaches?
There are many approaches now. We have the standard external beam treatment that used to be over a longer period of time, like 8.5 weeks. Nowadays, we have shorter courses that give treatment over a duration of 5.5 weeks or even shorter. Choosing the appropriate method is based on the individual patient and the state of their disease. Patients also have preferences and expectations we have to take into account. There are many different ways to treat prostate cancer and patients are becoming very aware of this.

In prostate cancer specifically, we see radiation combined a lot with androgen deprivation therapy (ADT). This is a means of lowering the testosterone to improve outcome, and this is done mainly in the intermediate- and poor-risk populations. The low-risk population does not need the addition of ADT. Typically, high-risk patients should receive ADT—at least, that is what the data show. Unless the patient absolutely does not want the treatment or has some kind of contraindication, that would be the standard approach.

What are the toxicities associated with radiation?
We see a lot of urinary toxicities, both acute and long-term ones. The proximity of the rectum to the prostate causes rectal toxicities, such as bleeding and radiation proctitis. We have a number of ways to minimize these now. We use hydrogel that is placed between the rectum and prostate in order to increase the distance between the 2 areas. If [these toxicities do] happen, then it depends how severe it is. Usually a conservative approach is preferable [in the management of these adverse events].

Not all of these toxicities are reversible. For example, impotence is something that can happen. Patients experience a decline over time and then it becomes irreversible. They can be treated with different options, and we counsel the patient on these options.

What are the biggest remaining challenges with radiation in prostate cancer?
The biggest challenge is access for the patients who have longer treatment courses. Patients have to travel to the facility, and a lot of times they are on the road longer than they are receiving the treatment. We are looking forward to improving travel time by offering shorter treatment courses. We will continue to develop more of these shorter treatments.

More patients with low-risk disease are also opting for active surveillance. We need to do a better job of identifying the patients who are considered low-risk and may do fine from surveillance and no immediate treatment. Of course, we also need to optimize the high-risk patients. PSA levels are not the only indicator of risk, and we are developing new tests to sort through these patients.

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