Standardized guidelines established in part by the US Food and Drug Administration are helpful when attempting to evaluate the efficacy of therapy with regard to survival, progression-free survival, and shrinkage of tumor, among other factors. None of those end points encompass the totality of the patient experience (eg, how patients feel when they are receiving the therapy). Standardized adverse event reporting is important, but it does not quite capture the patient experience.

When I evaluate PROs, I think about what the patients perceive during the course of their therapy. That is a critical element that we, as clinicians, should remain mindful of. There are some PROs that might be considered relatively simple (eg, pain) that are clearly relevant to patients. However, the interpretation of these outcomes can be a bit complex because we may not have clear data on analgesic usage or palliative radiation usage and how that relates to pain. Nevertheless, it is the patient’s voice that we hear when pain is described. We can take that into a variety of PROs, such as things that relate to cognition, fatigue, activities of daily living, and how well they are able to accomplish daily activities. PROs are a critical aspect of understanding clinical trials and are perhaps reflected in the clinic by time set aside to discuss with patients how therapies might affect them.

Patients can have different perceptions of a therapy that may only be captured by the PROs. Distinctions can appear even among agents in the same class of drugs. For instance, we have multiple approved agents that bind to the androgen receptor. These include drugs such as enzalutamide, apalutamide, and darolutamide. It turns out that there may be differences in their passage through the blood-brain barrier that provide distinctions regarding cognitive side effects and possibly even fatigue. Individual clinicians will need to gain their own experience, and, to me, there is nothing more important than the experiences reported by individual patients when we are in the clinic.

The different treatment modalities for prostate cancer have clearly different effects on patients and on PROs. Chemotherapy, which is well known in terms of its toxicity profile, is an essential aspect of patient management for advanced prostate cancer. We have life-prolonging data from docetaxel and cabazitaxel. Likewise, the novel antiandrogens also prolong survival and are associated with a different set of side effects. While these agents are critically important, there are opportunities for improvement, and we consider both survival and metrics derived from the patient experience (eg, quality of life) when assessing new and emerging therapies.