Comparing the long-term effects of two intensity modulated radiation therapies in localized prostate cancer

The study compared the long-term effects of moderate hypofractionated intensity-modulated radiation therapy (H-IMRT) and conventionally fractionated IMRT (C-IMRT) on outcomes in patients with localized prostate cancer (PC). The authors found that H-IMRT was similarly effective compared to C-IMRT after 10 years of therapy in such patients.

Localized PC does not spread beyond prostate gland. It can be treated with IMRT. IMRT precisely targets the prostate tumor without affecting surrounding tissues. H- and C-IMRT differ in doses and intensities. H-IMRT has several advantages related to cost, toxicity and early treatment outcomes. However, the effects on long-term outcomes in high-risk (HR) patients are unknown.

The study included 303 men with intermediate-risk (IR) and HR localized PC. C-IMRT group had 152 and H-IMRT had 151 patients. Patients were followed-up for 122.9 months on average. Androgen deprivation therapy (ADT) was given for 24.2 months to HR and 4.2 months to IR patients, on average. ADT is a hormonal therapy that prevents prostate cancer cells’ growth.

The frequency of biochemical and/or clinical disease failure (BCDF) was 28.3% for all patients, over 10 years. Biochemical failure (BF) involves increasing levels of prostate-specific antigen (PSA; a blood protein that increases in PC) without cancer symptoms. Clinical failure means the cancer has relapsed and has symptoms.

The 10-year BCDF rates were 25.9% for C-IMRT and 30.6% for H-IMRT. Frequencies of BF for 10 years were 21.1% for C-IMRT and 25.4% for H-IMRT groups. Local recurrence (LR) means cancer has returned to the same place where it started. 10-year LR rates were 4.7% for C-IMRT and 4% for H-IMRT. Metastasis or cancer spread to other organs occurred in 14.3% for H-IMRT and 6.4% for C-IMRT at 10 years. 

The study concluded that H-IMRT and C-IMRT had similar long-term outcomes in patients with localized PC. 

This study was designed to demonstrate superior outcomes upon H-IMRT than C-IMRT. It had the longest follow-up time compared to other similar studies.