Vol 18, No 5 (2013)
Original research articles
Published online: 2013-09-01

open access

Page views 158
Article views/downloads 220
Get Citation

Connect on Social Media

Connect on Social Media

Radiobiological comparison of two radiotherapy treatment techniques for high-risk prostate cancer

Trinitat García Hernández1, Aurora Vicedo González1, Jorge Pastor Peidro2, Juan V. Ferrando1, Luis Brualla González1, Domingo Granero Cabañero1, José López Torrecilla2
DOI: 10.1016/j.rpor.2012.12.006
Rep Pract Oncol Radiother 2013;18(5):265-271.

Abstract

Background

To make a radiobiological comparison, for high risk prostate cancer (T3a, PSA[[ce:hsp sp="0.25"/]]>[[ce:hsp sp="0.25"/]]20[[ce:hsp sp="0.25"/]]ng/ml or Gleason[[ce:hsp sp="0.25"/]]>[[ce:hsp sp="0.25"/]]7) of two radiotherapy treatment techniques. One technique consists of a treatment in three phases of the pelvic nodes, vesicles and prostate using a conventional fractionation scheme of 2[[ce:hsp sp="0.25"/]]Gy/fraction (SIMRT). The other technique consists of a treatment in two phases that gives simultaneously different dose levels in each phase, 2[[ce:hsp sp="0.25"/]]Gy/fraction, 2.25[[ce:hsp sp="0.25"/]]Gy/fraction and 2.5[[ce:hsp sp="0.25"/]]Gy/fraction to the pelvic nodes, vesicles and prostate, respectively (SIBIMRT).

Materials and methods

The equivalent dose at fractionation of 2[[ce:hsp sp="0.25"/]]Gy (EQD2), calculated using the linear quadratic model with α/βprostate[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]1.5[[ce:hsp sp="0.25"/]]Gy, was the same for both treatment strategies. For comparison the parameters employed were D95, mean dose and Tumour Control Probabilities for prostate PTV and D15, D25, D35, D50, mean dose and Normal Tissue Complication Probabilities for the rectum and bladder, with physical doses converted to EQD2. Parameters were obtained for α/βprostate[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]1.5, 3 and 10[[ce:hsp sp="0.25"/]]Gy and for α/βoar[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]1, 2, 3, 4, 6 and 8.

Results

For prostate PTV, both treatment strategies are equivalent for α/βprostate[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]1.5[[ce:hsp sp="0.25"/]]Gy but for higher α/βprostate, EQD2 and TCP, decrease for the SIBIMRT technique. For the rectum and bladder when α/βoar[[ce:hsp sp="0.25"/]]≤[[ce:hsp sp="0.25"/]]2[[ce:hsp sp="0.25"/]]Gy, EQD2 and NTCP are lower for the SIMRT technique or equal in both techniques. For α/βoar[[ce:hsp sp="0.25"/]]≥[[ce:hsp sp="0.25"/]]2–3[[ce:hsp sp="0.25"/]]Gy, EQD2 and NTCP increase for the SIMRT treatment.

Conclusions

A comparison between two radiotherapy techniques is presented. The SIBIMRT technique reduces EQD2 and NTCP for α/βoar from 2 to 8[[ce:hsp sp="0.25"/]]Gy.

Article available in PDF format

View PDF Download PDF file



Reports of Practical Oncology and Radiotherapy