International journal of radiation oncology, biology, physics
-
Int. J. Radiat. Oncol. Biol. Phys. · Jan 2004
Perineural invasion is associated with increased relapse after external beam radiotherapy for men with low-risk prostate cancer and may be a marker for occult, high-grade cancer.
To investigate the risk of postradiotherapy prostate-specific antigen (PSA) failure on the basis of pretreatment risk factors in prostate cancer patients with and without perineural invasion (PNI) in prostate biopsy specimens and to explain the observation that otherwise low-risk patients with PNI experience decreased freedom from PSA failure after external beam radiotherapy (RT). ⋯ A decrement in PSA outcome after RT for low-risk patients with PNI-positive biopsy specimens was found. The association between PNI and high Gleason score provides a possible explanation for the loss of statistical significance of PNI in the Cox regression multivariate analysis of the high-risk cohort. The data suggest that PNI found in the biopsy specimen of an otherwise low-risk patient predicts for occult high-grade disease that is missed owing to the sampling error associated with prostate biopsy. The association between PNI and a high Gleason score argues for the use of more aggressive therapy, such as hormonal therapy with RT and/or dose escalation, in these select patients.
-
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.
-
Int. J. Radiat. Oncol. Biol. Phys. · Jan 2004
The use of hypofractionated intensity-modulated irradiation in the treatment of glioblastoma multiforme: preliminary results of a prospective trial.
Despite major advances in treatment modalities, the prognosis of patients with glioblastoma multiforme (GBM) remains poor. Exploring hypofractionated regimens to replace the standard 6-week radiotherapy schedule is an attractive strategy as an attempt to prevent accelerated tumor cell repopulation. There is equally interest in dose escalation to the gross tumor volume where the majority of failures occur. We report our preliminary results using hypofractionated intensity-modulated accelerated radiotherapy regimen in the treatment of patients with GBM. ⋯ This hypofractionated accelerated irradiation schedule using forward planning (step-and-shoot) hypofractionated, intensity-modulated accelerated radiotherapy is feasible and seems to be a safe treatment for patients with GBM. A 2-week reduction in the treatment time may be of valuable benefit for this group of patients. However, despite this accelerated regimen, no survival advantage has been observed.
-
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.