International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Feb 2004
Antisense MDM2 sensitizes prostate cancer cells to androgen deprivation, radiation, and the combination.
Antisense MDM2 (AS) sensitizes a variety of tumor cell types, including prostate cancer, to radiation and chemotherapy. We have previously described that AS enhances the apoptotic response to androgen deprivation (AD) and that this translates into a reduction in overall cell survival, as measured by clonogenic assay. Because AD + radiation (RT) is a key strategy for the treatment of men with high-risk prostate cancer, AS was tested for the ability to sensitize cells to the combination of AD+RT. ⋯ AS sensitizes cells to AD, RT, and AD+RT and shows promise in the treatment of the full range of patients with prostate cancer. AS has the potential to sensitize the primary tumor to AD+RT and metastasis to AD.
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Int. J. Radiat. Oncol. Biol. Phys. · Feb 2004
Comparative StudyThree-dimensional conformal vs. intensity-modulated radiotherapy in head-and-neck cancer patients: comparative analysis of dosimetric and technical parameters.
The use of intensity-modulated radiotherapy (IMRT) is now widely advocated for the treatment of head-and-neck cancers, to increase the therapeutic ratio of radiotherapy used as sole modality of treatment or in combination with chemotherapy. This report aims to summarize the technical and dosimetric factors to be taken into consideration to assess the respective advantages of the various high conformality treatments in radiotherapy, especially in the framework of quality assurance procedures. ⋯ Elective target volumes ranged from 530 to 1151 cm(3) with a mean of 780 +/- 141 cm(3). Boost volumes ranged from 248 to 832 cm(3) with a mean of 537 +/- 165 cm(3). Thirty-two dose plans were generated with static technique and 10 with dynamic. In the static mode, 6.8 +/- 3.4 fields were applied on average with 12.5 +/- 1.3 segments per field. In the static mode, 264 +/- 56 MU per Gy were erogated, whereas in the dynamic mode, 387 +/- 126 MU per Gy were erogated, to be compared to 147 +/- 20 computed for reference 3DCRT plans. For all target volumes in general, conformity was improved compared to 3DCRT (e.g. V(95) increased from 85% to 93% with p < 0.001, or equivalent uniform dose normalized to prescribed dose increased from 0.86 to 0.96 with p = 0.002). Irradiation of parotid glands or spinal cord improved, as well: For parotids, D(2/3V) reduced from 59 Gy to 41 Gy (p < 0.001). For spinal cord, D(max) reduced from about 40 Gy to about 30 Gy (p < 0.001).
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 2004
Evaluation of salivary gland function after treatment of head-and-neck tumors with intensity-modulated radiotherapy by quantitative pertechnetate scintigraphy.
To evaluate salivary gland function after inversely planned stereotactic intensity-modulated radiotherapy (IMRT) for tumors of the head-and-neck region using quantitative pertechnetate scintigraphy. ⋯ Using IMRT, it is possible to protect the parotid glands and reduce the incidence and severity of xerostomia in patients. Doses <26-30 Gy significantly preserve salivary gland function. The results support the hypothesis that application of IMRT does not lead to increased local failure rates.
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 2004
Influence of prostate volume on dosimetry results in real-time 125I seed implantation.
Achieving a minimal dose of 140 Gy to 90% of the prostate (D90) on postimplant dosimetry has been shown to yield improved biochemical control by 125I brachytherapy, and a D90 >180 Gy can be associated with increased long-term toxicity of seed implantation. Significant enlargement of the prostate on postimplant CT compared with the ultrasound (US) volume at implantation (CT/US ratio) has been associated with lower dose results, but other factors predicting for high or low doses are not well established. We determined whether the prostate size at implantation influenced the CT/US ratio results affecting postimplant dosimetry or predicted for D90 values <140 or >180 Gy in patients implanted with 125I in a community hospital setting. ⋯ Ninety percent of patients implanted by community-level practitioners using reference tables and real-time US-guided implantation achieved a D90 outcome of > or =140 Gy. Significant differences in dose outcomes <140 Gy and >180 Gy occurred related to PV. Those with prostates <25 cm3 had a 20% frequency of D90 <140 Gy, unrelated to excessive postimplant volume enlargement or insufficient activity per reference table, suggesting that the activity-to-volume recommendations may not allow for much variance in final seed position. Such seed displacement may contribute to lower doses, most commonly in small glands. One may consider increasing the activity implanted in small prostates, because a D90 >180 Gy occurred in only 7% of these cases. Patients with glands >40 cm3 were 25% likely to have a D90 result >180 Gy and were at only 3% risk of a D90 <140 Gy. These patients may benefit from intraoperative dosimetry or a reduction in implant activity.