Clinical estimation of α/β values for prostate cancer from isoeffective phase III randomized trials with moderately hypofractionated radiotherapy

Tissue markers may be helpful in enhancing prediction of radiation therapy (RT) failure of prostate cancer (PCa). Among the various biomarkers tested in Phase III randomized trials conducted by the Radiation Therapy Oncology Group, p16, Ki-67, MDM2, COX-2, and PKA yielded the most robust data in predicting RT failure. Other pathways involved in RT failure are also implicated in the development of castration-resistant PCa, including the hypersensitive androgen receptor, EGFR, VEGF-R, and PI3K/Akt. Most of them are detectable in PCa tissue even at the time of initial diagnosis. Emerging evidence suggests that RT failure of PCa results from a multifactorial and heterogeneous disease process. A number of tissue markers are available to identify patients at high risk to fail RT. Some of these markers have the promise to be targeted by drugs currently available to enhance the efficacy of RT and delay disease progression.

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Moderate Hypofractionation in High-Risk, Organ-Confined Prostate Cancer: Final Results of a Phase III Randomized Trial

Journal of Clinical Oncology ◽

10.1200/jco.2016.70.4189 ◽

2017 ◽

Vol 35 (17) ◽

pp. 1891-1897 ◽

Cited By ~ 77

Author(s):

Giorgio Arcangeli ◽

Biancamaria Saracino ◽

Stefano Arcangeli ◽

Sara Gomellini ◽

Maria Grazia Petrongari ◽

...

Keyword(s):

Prostate Cancer ◽

High Risk ◽

Randomized Trial ◽

Gleason Score ◽

Late Toxicity ◽

Phase Iii ◽

Hypofractionated Radiotherapy ◽

Significant Prognostic Factor ◽

Prognostic Variables ◽

Genitourinary Toxicity

Purpose To report the final results on treatment outcomes of a randomized trial comparing conventional and hypofractionated radiotherapy in high-risk, organ-confined prostate cancer (PCa). Patients and Methods This single-institution, randomized clinical trial, conducted from January 2003 to December 2007, enrolled 168 patients with high-risk PCa who were randomly assigned in a 1:1 ratio to conventional (80 Gy in 40 fractions in 8 weeks) or hypofractionated radiotherapy (62 Gy in 20 fractions in 5 weeks) to prostate and seminal vesicles. The primary outcome measure was late toxicity. Additional outcomes were freedom from biochemical failure (FFBF), prostate cancer–specific survival (PCaSS), and overall survival (OS), evaluated on an intention-to-treat basis. Results A total of 85 patients were assigned to conventional and 83 to hypofractionated radiotherapy. At a median follow-up of 9 years (interquartile range, 7.5 to 10.1 years), no differences was observed in physician-assessed late gastro intestinal and genitourinary toxicity greater than or equal to grade 2 ( P = .68 and .57, respectively) were found between the two arms. The 10-year FFBF rate was 72% in the hypofractionation group and 65% in the conventional fractionation group ( P = .148). Ten-year OS rates were 75% in the hypofractionation group and 64% in the conventional group, respectively ( P = .22). The same features for 10-year PCaSS were 95% and 88%, respectively ( P = .066). Hypofractionation, pretreatment prostate-specific antigen level, Gleason score, and clinical tumor stage for FFBF, and hypofractionation and Gleason score for PCaSS were significant prognostic variables on the multivariate analysis. Conclusion Long-term findings showed that hypofractionated radiotherapy failed the intent of either reducing physician-assessed late toxicity or maintaining the same efficacy. A postrandomization analysis, however, revealed that hypofractionation was a significant prognostic factor for FFBF and PCaSS, when adjusted for clinical prognostic variables.

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