Published this month in the International Journal of Radiation Oncology, Biology, Physics*, findings first authored by Joan Carles, Principal Investigator of VHIO’s Genitourinary, CNS Tumors, Sarcoma & Cancer of Unknown Primary Site Group, in collaboration with groups including VHIO’s Radiation Oncology led by Jordi Giralt (Vall d’Hebron Barcelona Hospital Campus), and Radiation Oncology at the Hospital del Mar, IMIM, Barcelona, evidence the clinical feasibility and tolerability of treating high-risk localized prostate cancer with standard radiotherapy plus concomitant docetaxel treatment followed by 3 years’ androgen deprivation.
The additional clinical benefit of administering docetaxel concurrent to the standard-of-care of metastatic prostate cancer has become routine in metastatic castration-resistant and in metastatic hormone-sensitive prostate cancer patients. This multicenter Spanish phase II study was designed to establish the impact of docetaxel on high risk localized prostate cancer patients’ survival.
Commenting for VHIO Communications, Joan Carles observed, “Results from our study point to a potential new approach for the treatment of patients with high risk localized prostate cancer. Essentially, as a first step, we have shown that concurrent administration of docetaxel with radiotherapy does not significantly increase the toxicity profile.”
Findings show that 95% of the patients presented at least one adverse, yet manageable and mild, event. While 19.4% of patients experienced a severe adverse event from treatment with docetaxel, they could be well managed by delaying therapy and dose reduction in 16 and 5 patients, respectively. This toxicity however, was mainly hematological. Only 3 patients, all of them receiving docetaxel, discontinued the regimen because of adverse events.
Results report similar recurrences in 5 year period of time among patients treated with and without docetaxel. Consistently, progression-free survival and overall survival at 5 years did not differ between treatment groups (up to 80-90% approximately). However, treatment with docetaxel seemed to modestly increase clinical benefit for patients, since the median biochemical recurrence-free survival and progression-free survival were not achieved in this arm.
Triggering certain controversy, prostate-specific antigen (PSA) levels have been proposed as indicators in the diagnosis of prostate cancer. Despite the unclear role of PSA in the detection of this disease, PSA levels were reported as comparable among groups.
Considering the results, Joan Carles continued, “The small sample size of the study might have undervalued the benefit of adding docetaxel to radiotherapy. Moreover, the data is still immature since the 5-year follow up period is too short compared to the long term androgen-deprivation that these patients harbor, a factor that might have influenced our results.”
Future studies with longer-term follow-up as well as expanded patient enrollment will be required to more precisely assess the efficacy of this novel approach and meet the primary endpoint.
“In our collective and determined efforts aimed at improving outcomes for these patients, we are now keen to establish whether this combined treatment actually increases the clinical benefit of this particular population of patients suffering from high risk localized prostatic cancer.”
*Carles J, Gallardo E, Doménech M, Font A, Bellmunt J, Figols M, Mellado B, Sáez MI, Suárez C, Méndez MJ, Maroto P, Luque R, de Portugal T, Aldabo R, Bonfill T, Morales-Barrera R, García J, Maciá S, Maldonado X, Foro P, Phase 2 Randomized Study of Radiation Therapy and 3-Year Androgen Deprivation With or Without Concurrent Weekly Docetaxel in High-Risk Localized Prostate Cancer Patients. Int J Radiat Oncol Biol Phys 103, 2, 344–352 (2019).