Can intensity-modulated radiotherapy improve cancer control in high-risk prostate cancer?

This study examined the efficacy of two different types of radiation therapies among patients with localized (confined) prostate cancer. 

One of the common treatments for prostate cancer is radiation therapy. This procedure directs beams of radiation through the skin at the cancer in order to destroy the main tumor and any nearby cancer cells. Three-dimensional (3-D) conformal therapy was previously the conventional radiotherapy for men suffering from prostate cancer. Intensity-modulated radiotherapy is a specialized form of 3D-conformal therapy that uses advanced technology to plan a precise dose of radiation based on tumor size, shape and location, thus minimizing the damage to the healthy surrounding tissue.

High-dose treatments may be limited by their toxic or harmful effect on the healthy tissues that surround the target tumor. Toxicity can lead to complications such as erectile dysfunction as well as intestinal and urinary infections. In this study, the comparison between the two modalities was based on evaluating the level of toxicity and cancer control. The latter, was assessed by the need for salvage androgen-deprivation therapy. Androgen deprivation therapy is a hormonal therapy used during (concurrent) or after (not concurrent; salvage therapy) radiotherapy; it decreases the amount of testosterone available in the body, thus stopping the growth of prostate cancer cells.

The present study included men aged 66 years or above, diagnosed with localized prostate cancer. 11,039 patients underwent intensity-modulated radiotherapy and 6,976 patients received 3D-conformal therapy. Approximately 47% of patients undergoing radiotherapy also received concurrent hormone androgen deprivation therapy. Low risk patients were defined as patients whose cancer had lower risk of becoming malignant, whereas high risk patients were more likely to develop aggressive and invasive cancer.

The probability of low-risk patients experiencing complications or requiring salvage therapy at 5-years was comparable between intensity-modulate radiotherapy and 3-D conformal therapy.

The probability of high-risk patients experiencing complications at 5-years was comparable between the modalities. However, among high-risk patients, those undergoing intensity modulated radiotherapy without concurrent hormone androgen deprivation therapy were less likely to need salvage therapy (16%) than those undergoing 3-D conformal therapy (20%).

The 5-year overall mortality (the percentage of patients that had died by 5 years post-procedure procedure) was 20% for 3D-conformal therapy compared with 22% for intensity-modulated radiotherapy.

Intensity-modulated radiotherapy may improve cancer control in high-risk patients who do not avail of concurrent androgen deprivation therapy.

This study only reported complications that required an intervention.