Purpose/Objective: Small bowel toxicity is an increasingly recognized complication of radical treatment of cervical cancer. Small bowel dose constraints have not been part of ICRU 38 guidelines for cervical brachytherapy. We postulated that bladder dose received during brachytherapy could serve as a surrogate for the dose delivered to small bowel and hence the risk of toxicity.
Materials/Methods: The records of all 124 patients who received radical chemoradiotherapy for cervical cancer from 2000 to 2007 in our institution were reviewed. These patients received Selectron MDR brachytherapy with use of Plato or TheraPlan Plus planning systems (Nucletron, Netherlands) for calculation of dose to ICRU points on planar x-ray images. The patients were analysed with regard to BED, EQD2 and ICRU point dose to bladder. All data of interest were available for 92 patients.
Results: The dose prescribed to Point A ranged between 23 and 28 Gy (median 24 Gy). Five (5.4%) of these patients developed small bowel toxicity requiring ileostomy formation following radical chemoradiotherapy. The median time to surgery was 17 months. BED and EQD2 were equivalent in the surgical and non-surgical groups. Mean bladder dose in the surgery group was 17.64 Gy (SD 6.89 Gy) and 19.88 Gy (SD 6.61 Gy) in the non-surgery group (unpaired t test; p = 0.4663).
Conclusion: The rate of ileostomy formation in our institution is comparable to that of published data. There was no positive correlation between patients requiring ileostomy and bladder dose received during brachytherapy. ICRU point dose to bladder may not be meaningful in this context. Further guidance is required in this area and review of other potential surrogates is desirable. The shift to CT and MR based IGRT should aid more accurate assessment of small bowel dose during brachytherapy.
Lyons, C,
Workman, G,
O'Toole, M,
Robinson, K,
Clarke, J,
Use of Bladder Dose as a Surrogate for Small Bowel Toxicity in Radical Brachytherapy for Cervical Cancer. Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL.
http://archive.rsna.org/2009/8500796.html
