Radiotherapy for Unfavorable Intermediate Prostate Cancer

In this episode of BackTable Urology, Dr. Aditya Bagrodia interviews Dr. Neil Desai, a radiation oncologist from UT Southwestern, about radiation therapy indications, algorithms, side effects, and prognoses for unfavorable intermediate risk prostate cancer patients.

Intermediate risk prostate cancer is defined by a Gleason grading score of 7 or more and a PSA level above 10 ng/mL but below 20 ng/mL. Radiation therapy is a common unimodal or multimodal therapy in these prostate cancer patients. Dr. Desi recommends additional imaging via MRI to stage the cancer before starting treatment. Additionally, bone scans and colonoscopies may be beneficial in order to find metastases and colon cancer, respectively, that can also be treated with radiation therapy (RT).

A thorough patient history is important to obtain before choosing a radiation therapy option. Dr. Desai divides his history into 2 different categories-–patient-specific factors and disease-specific factors. For patient-specific factors, baseline urinary symptoms, metabolic disorders, hormonal disorders, patient preferences, and baseline sexual potency are important. Contraindications under this category include connective tissue disorders, ulcerative colitis, and Crohn’s disease. Prostate anatomy, such as large median lobes, also need to be assessed. Dr. Desai emphasizes that many of these contraindications do not totally rule out the possibility of radiation therapy, but just warrant careful consideration of the intensity of radiation used on the patient. Next, he discusses disease-specific factors, such as the efficacy of androgen deprivation therapy (ADT). The majority of prostate cancer patients are started on ADT for 4-6 months first, and then begin RT. Dr. Desai notes that delayed castration resolution times are possible in older patients, so a baseline testosterone level must be started before ADT has begun in order to assess its efficacy. Also, he allows his patients to start on ADT for one month before RT to give them an opportunity to adapt to the side effects of one therapy at a time. Then, he and Dr. Bagrodia discuss the exciting new field of second-generation ADT.

Next, Dr. Desai summarizes his explanation of RT to his patients. He starts by delineating the differences between internal and external RT, which exist on a continuum. Based on which RT option the patient chooses, the acuity and duration of lower urinary tract symptoms (LUTS) will vary. The RT option he most commonly recommends to patients without contraindications is brachytherapy with an external beam, which results in less cancer recurrence but more LUTS. However, he acknowledges that brachytherapy may not be offered in all centers, may have reduced efficacy in big prostates, and may be an unfavorable choice in patients with severe LUTS. In these cases, conventional fractionation, hypofractionation, or ultra hypofractionation are better options. Furthermore, Dr. Desai dives into more technical aspects of RT, such as the importance of a full bladder as a form of protection from external beam RT and the superiority of photon-based RT over proton-based RT. Additionally, he recommends measuring PSA levels after 3 months post-RT to minimize the chance of picking up noise. He mentions that physicians should address the “PSA bounce”, a fluctuation of PSA level post-RT followed by a transient resolve, with their RT patients because it may be a source of patient anxiety.

Finally, Dr. Desai highlights the importance of the collaboration between urologists and radiation oncologists. The patient should be made aware that both specialties are in communication and feel comfortable discussing treatment options with both sides. Dr. Desai will usually advise his patients to meet with their urologists before making a final decision on their radiation therapy. Also, it is important for both sides to coordinate any new tests and check in periodically with patients.