Mark Klein. I find that to be a very attractive approach. I’m assuming you do that for any systemic therapy where people have maybe 1 or 2 sites and they do not have a big PSA jump. Do you have a number of sites that you’re willing to radiate? And then, when you do that, what radiation fractionation and dosing do you use? Is there any observational data behind that for efficacy?
Abhishek Solanki. It is a patient by patient decision. Some patients, if they have a very rapid pace of progression shortly after starting systemic therapy and metastases have grown in several areas, we think that perhaps this person may benefit less from aggressive local therapy. But if it’s somebody who has been on systemic therapy for a while and has up to 3 sites of disease growth, we consider SBRT for oligoprogressive disease. Typically, we’ll use SBRT, which delivers a high dose of radiation over 3 to 5 treatments. With SBRT you can give a higher biologic dose and use more sophisticated treatment machines and image guidance for treatments to focus the radiation on the tumor area and limit exposure to normal tissue structures.
In prostate cancer to the primary site, we will typically do around 35 to 40 Gy in 5 fractions. For metastases, it depends on the site. If it’s in the lung, typically we will do 3 to 5 treatments, giving approximately 50 to 60 Gy in that course. In the spine, we use lower doses near the spinal cord and the cauda equina, typically about 30 Gy in 3 fractions. In the liver, similar to the lung, we’ll typically do 50-54 Gy in 3-5 fractions. There aren’t a lot of high-level data guiding the optimal dose/fractionation to metastases, but these are the doses we’ll use for various malignancies.
Treatment Options for Patients With Adverse Events
Mark Klein. I was just reviewing the 2004 study that randomized patients to mitoxantrone or docetaxel for up to 10 cycles.14,15 Who are good candidates for docetaxel after they have exhausted abiraterone and enzalutamide? How long do you hold to the 10-cycle rule, or do you go beyond that if they’re doing well? And if they’re not a good candidate, what are some options?
Julie Graff. The best candidates are those who are having a cancer-related AE, particularly pain, because docetaxel only improves survival over mitoxantrone by about 2.5 months. I don’t talk to patients about it as though it is a life extender, but it seems to help control pain—about 70% of patients benefited in terms of pain or some other cancer-related symptom.14
I have a lot of patients who say, “Never will I do chemotherapy.” I refer those patients to hospice, or if they’re appropriate for radium-223, I consider that. I typically give about 6 cycles of chemotherapy and then see how they’re doing. In some patients, the cancer just doesn’t respond to it.
I do tell patients about the papers that you mentioned, the 2 studies of docetaxel vs mitoxantrone where they use about 10 cycles, and some of my patients go all 10.14,15 Sometimes we have to stop because of neuropathy or some other AE. I believe in taking breaks and that you can probably start it later.