Is intensity-modulated radiotherapy for prostate cancer ready for prime-time?

RODRIGUES G. Is intensity-modulated radiotherapy for prostate cancer ready for prime-time? Can J Urol 2012;19(4):6381-6382. the therapeutic ratio between the positive anticancer effect of radiotherapy on macroscopic and microscopic disease and the negative normal tissue effects leading to both acute and late radiotherapy toxicities. In the context of prostate cancer radiotherapy, these technologies attempt to improve cancer endpoints such as biochemical control and overall survival by escalating dose to the prostate and minimizing dose to adjacent radiosensitive structures such as the rectum, bladder, and penile bulb. In this issue of The Canadian Journal of Urology, Ohri et al report on a systematic review and meta-analysis of late toxicity effects as measured with a standardized late radiotherapy toxicity scale.1 They report that IMRT and PBRT external-beam radiotherapy was associated with significant declines in reported severe GI toxicity when compared to 3-DCRT. Also, they confirmed that prostate dose-escalation can be related with additional moderate and severe late toxicity. Both these findings confirm the importance of therapeutic ratio optimization in order to attempt to deliver maximum dose to the prostate target while using advanced radiotherapy delivery technologies to reduce normal tissue dose. Recently, Cancer Care Ontario commissioned a series of systematic reviews to assess the indications and evidence related to the implementation of IMRT in a series of tumor sites including prostate cancer (www. cancercare.on.ca). Bauman et al found that a review of the available evidence demonstrated equivalence or superiority of IMRT over 3-DCRT dose-escalated (> 70 Gy in 2 Gy daily fractions) external-beam radiotherapy The integration of technology in medicine continues to transform patient care in terms of various important endpoints including treatment efficacy, efficiency, economics, and toxicity. The practice of radiation oncology has undergone substantial transformational change over the past two decades with the advent of several interlinked technologies. Classical radiation oncology treatment techniques were generally planned using two-dimensional (2-D) techniques. The use of these 2-D techniques significantly limited the maximum dose to the cancer target(s) due to the addition of large safety margins for target/delivery uncertainty as well as the lack of conformal avoidance of normal tissue dose to radiosensitive structures. Newer technologies have improved the targeting of cancer (e.g. CT, MRI), the conformality of radiotherapy (three-dimensional conformal radiotherapy – 3-DCRT, intensity modulated radiotherapy PBRT, low-dose rate and high-dose rate brachytherapy, and protonbeam radiotherapy PBRT) and the accuracy/precision of treatment delivery (patient immobilization, fiducial markers, and image-guided radiotherapy IGRT). All of these technologies work to optimize