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Clinical Trial
. 2011 Jun 1;80(2):614-20.
doi: 10.1016/j.ijrobp.2010.06.050. Epub 2010 Oct 6.

Parameters favorable to intraprostatic radiation dose escalation in men with localized prostate cancer

Nadine Housri  1 , Holly Ning, John Ondos, Peter Choyke, Kevin Camphausen, Deborah Citrin, Barbara Arora, Uma Shankavaram, Aradhana Kaushal
Affiliations
Clinical Trial

Parameters favorable to intraprostatic radiation dose escalation in men with localized prostate cancer

Nadine Housri et al. Int J Radiat Oncol Biol Phys. .

Abstract

Purpose: To identify , within the framework of a current Phase I trial, whether factors related to intraprostatic cancer lesions (IPLs) or individual patients predict the feasibility of high-dose intraprostatic irradiation.

Methods and materials: Endorectal coil MRI scans of the prostate from 42 men were evaluated for dominant IPLs. The IPLs, prostate, and critical normal tissues were contoured. Intensity-modulated radiotherapy plans were generated with the goal of delivering 75.6 Gy in 1.8-Gy fractions to the prostate, with IPLs receiving a simultaneous integrated boost of 3.6 Gy per fraction to a total dose of 151.2 Gy, 200% of the prescribed dose and the highest dose cohort in our trial. Rectal and bladder dose constraints were consistent with those outlined in current Radiation Therapy Oncology Group protocols.

Results: Dominant IPLs were identified in 24 patients (57.1%). Simultaneous integrated boosts (SIB) to 200% of the prescribed dose were achieved in 12 of the 24 patients without violating dose constraints. Both the distance between the IPL and rectum and the hip-to-hip patient width on planning CT scans were associated with the feasibility to plan an SIB (p = 0.002 and p = 0.0137, respectively).

Conclusions: On the basis of this small cohort, the distance between an intraprostatic lesion and the rectum most strongly predicted the ability to plan high-dose radiation to a dominant intraprostatic lesion. High-dose SIB planning seems possible for select intraprostatic lesions.

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Figures

Fig. 1
Fig. 1
Endorectal coil MR image of the prostate gland. Arrow indicates the lesion suspicious for carcinoma.
Fig. 2
Fig. 2
Planning CT with contours of prostate, intraprostatic lesion, and rectum.
Fig. 3
Fig. 3
(a) Example of successful treatment plan. (b) Isodose line key.
Fig. 4
Fig. 4
Categorization of patients into dose cohorts according to feasibility of dose escalation.
See this image and copyright information in PMC

References

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