Canadian researchers have discovered no evidence of cognitive effects in males being treated for metastatic, castration-resistant prostate cancer, or mCRPC, the most advanced form of prostate cancer. Following the failure of prior medications, the men were treated with one of four distinct therapies:
A chemotherapy drug called docetaxel
Enzalutamide is a second-generation hormonal therapy that is used when first-generation hormonal treatments fail.
Abiraterone is a second-generation hormonal therapy as well.
Radium-233, a radioactive isotope used to treat prostate cancer that has spread to the bones.
All of these drugs have been shown to prolong life, but published data on their cognitive side effects are limited, and no such data for docetaxel or radium-233 were available.
The researchers enlisted 155 men between the ages of 73 and 76, the majority of whom had completed some form of a college education. The cognitive functioning of the participants was assessed twice: once before the cancer treatments began and again after the treatments were completed (this amounted to six months for docetaxel and radium-233, and roughly 11 months for enzalutamide and abiraterone).
Three tests were used:
The first was one in which the men had to connect a sequence of 25 numbers in order, another in which they had to connect an alternating sequence of numbers and letters, and a third in which they had to assess cognitive abilities such as short-term memory, attention, orientation, and language.
The researchers predicted that docetaxel chemotherapy would cause the most cognitive losses, with enzalutamide, a drug that can pass the blood-brain barrier, coming in second.
However, the results revealed that none of the therapies had any discernible cognitive impact, since test scores were comparable before and after treatment. Based on this promising discovery, the researchers concluded that most older men will not have cognitive decline while receiving treatment for mCRPC, regardless of the therapy they receive.
Because older males are rarely included in oncology research trials, the findings are significant. More research is needed, however, because the number of enrolled patients was limited, and the effects of other mCRPC therapies on cognition are unknown, according to the researchers.