Radiation Therapy

Evidence-based review of three-dimensional conformal radiotherapy for localized prostate cancer: an ASTRO outcomes initiative

International Journal of Radiation Oncology*Biology*Physics 62(1):3-19, May 1 2005
D E Morris, B Emami, P M Mauch, A A Konski, M L Tao, A K Ng, E A Klein, N Mohideen, M D Hurwitz, BA Fraas, M Roach 3rd, E M Gore, J E Tepper

Study purpose: This review analyzes the usefulness of an innovative type of radiation therapy, three-dimensional conformal radiotherapy (3D-CRT), in treating “localized” cancer within the prostate gland. The therapy uses 3-D imaging to map the cancer it is targeting and deliver radiation doses that are matched to the target’s size.

Study description: The review had three main objectives: 1) to analyze the medical literature to see how suitable 3D-CRT is for treating localized prostate cancer; 2) to address key questions about treatment and patients’ future prospects; 3) to develop information on whether 3D-CRT improves patients’ prospects in the treatment of localized prostate cancer compared with more conventional radiotherapy.

Findings: A review of the literature found that 3D-CRT reduces serious gastrointestinal problems compared with conventional radiation therapy. As well, 3D-CRT allows higher radiation doses to be delivered to the prostate with the same effects as lower doses of conventional radiation therapy. So far, 3D-CRT has not been shown to increase longevity, although few long-term studies exist. It is also unknown if patients benefit when 3D-CRT is carried out alongside androgen suppression therapy that blocks the body’s male hormones from aiding the growth of prostate cancer cells. The authors suggest that 3D-CRT may be of greatest benefit for patients with fast-growing prostate cancer contained within the prostate. Some evidence shows that 3D-CRT may be more helpful for patients who have high serum prostate-specific antigen (PSA) levels in PSA tests indicating the presence and severity of prostate cancer.

Conclusions: The authors conclude that 3D-CRT has met its “technological goal” and will be shown in the near future to be of more help to patients with cancer within the prostate gland than conventional radiation therapy. More studies are needed to assess 3D-CRT given alongside androgen suppression treatment.

Note: Three-dimensional conformal radiotherapy remains largely unavailable in Canada.

A Systematic Overview and Meta-analysis of Radiation Therapy Effects in Prostate Cancer

Acta Oncologica 43(4): 316-381, June 2004
Sten Nilsson, Bo Johan Norlén and Anders Widmark

Study purpose: This Swedish overview looks at the effects of radiation therapy on patients with prostate cancer. Radiation therapy is treatment that uses X-rays and other forms of radiation to destroy cancer.

Study description: The overview is based on results from studies involving 152,614 prostate cancer patients. The data is taken from one meta-analysis, 30 randomized trials, 55 prospective trials, and 210 retrospective studies. A meta-analysis is a statistical method combining study results in order to re-examine the overall evidence. Randomized trials randomly assign participants to different forms of treatment for research purposes, while prospective trials follow patients forward in time. A case-control study compares a group with a disease against a similar healthy group, and studies both groups’ medical records and lifestyles to learn what factors may be linked to disease.

Findings & Conclusions: Many of the studies show that results from external beam radiotherapy (beamed throughout the body to the cancer site) and brachytherapy (pellets giving off radiation that are implanted in the prostate) are similar to those of surgery to remove a cancerous prostate gland (radical prostatectomy). There is fairly strong evidence that men who have cancer within the prostate that may spread slightly (intermediate risk), or will probably spread more quickly and widely (high risk), benefit from a higher than usual total dose of radiation. It has not yet been shown that these men live any longer because of the treatment. Finally, the authors note the benefits of accompanying radiotherapy with androgen-deprivation treatment. This treatment uses medications to shut down the body’s production of male hormones that help prostate cancer cells grow. The studies indicate that short-term androgen-deprivation treatment given before and during radiotherapy may help men whose cancer is “locally advanced” (mostly contained within the prostate gland) live longer without disease. Men with cancer within the prostate who undergo androgen-deprivation therapy after radiotherapy may also live longer without disease. There is some evidence that androgen-deprivation treatment after radiotherapy helps patients with locally advanced prostate cancer live longer when compared to radiotherapy alone.