A new multinational study presented at the 2016 ASCO annual meeting showed that adjuvant docetaxel (Taxotere) without hormonal therapy did not improve the biochemical disease-free survival (BDFS) after radical prostate removal for men with high-risk prostate cancer. However, when used as monotherapy, docetaxel may generate quicker biochemical progression in a subgroup of patients as reported by Göran Ahlgren, MD, Ph.D., of Malmö University Hospital in Sweden, and colleagues.
Biochemical disease-free survival is the survival time of a person with prostate cancer during with a biochemical marker like PSA, or prostate-specific antigen, does not rise or rises very little for two to three consecutive occasions. If the patient relapses biochemically after treatment, his PSA levels have increased significantly. Typically, patients who undergo prostate cancer treatment should have nearly undetectable PSA levels, around or below 1.0ng/mL.
In the phase III study, 459 patients were randomized from 2005 to 2010 to either six weeks of docetaxel or surveillance. All six cycles were completed by 79.1% of the patients.
Mean age was 62.2, mean baseline PSA 0.156, and 83.7% had pT3 disease while 37.5 percent had GS 8-10 at randomization. Of the 308 patients that had a lymph node dissection, 55 (17.5%) had metastasis. Median follow-up was 56.8 months.
The patients who were followed for five years underwent a PSA test every three months. At the 5-year follow-up, the study was driven to show a 15 percent difference.
High-risk prostate cancer was defined as:
- pT2 with a positive margin if Gleason score (GS) 4+3 or higher
- pT3b >GS 3+4
- Any lymph node positive disease with >GS 3+4
Eight percent of patients total in arm A and 10 percent in Arm B had received salvage radiotherapy before the primary endpoint was reached.
There were six deaths from prostate cancer in arm A and three deaths in arm B despite having no deaths related to the treatment. Febrile neutropenia occurred in 18.7 percent of the patients in arm A.
The primary endpoint -- a rising PSA >0.5ng/ml -- was reached in 43.2 percent of patients overall; in 47.9 percent of patients (arm A) who received six cycles of adjuvant docetaxel (75 mg/m2 q 3 weeks); and in 38.9 percent of patients (arm B) who received surveillance.
While there was no significant difference between the BDFS curves (P=0.078), at 15 months, the curve of arm A crossed the curve of arm B, and it was parallel at a 10 percent lower level beyond 24 months, according to the authors.
James Mohler, M.D., of the Roswell Park Cancer Institute and the State University of New York at Roswell Park, both in Buffalo, N.Y., added, "Docetaxel has proven helpful in advanced prostate cancer -- castrate-resistant prostate cancer and high volume metastatic when combined with androgen deprivation therapy [ADT] -- when growth rates are high and a mitotic spindle targeted chemotherapy may have benefit."