A.R. Kagan

The Final Report of the Expert Panel for the Radiation Oncology Bone Metastasis Work Group of the American College of Radiology

BACKGROUND In the United States, at least half of the patients who are irradiated are done so with palliative intent. The most common presentation is the patient with bone metastasis. However, because current scientific outcome and technology techniques are insufficient for the creation of guidelines, the American College of Radiology created a work group of experts to formulate appropriateness criteria for the irradiation of bone metastasis. METHOD A MEDLINE search to help review the community practices was initiated. Twenty-five clinical vignettes were reviewed by a panel of experts. Recommendations for each vignette were prioritized and selected based on choices proposed by panel members. RESULT Doses in the range of 20 Gy in 5 fractions, 30 Gy in 10 fractions, or 35 Gy in 14 fractions are acceptable in most circumstances. Daily doses > 4.0 Gy were not commonly suggested. CIRCUMSTANCES: To determine optimal dose fractionation schemes, more emphasis needs to be put on the life expectancy of the patients. Rapid schedules are acceptable in patients with short life expectancy (i.e., < 3 months), but this hypothesis needs to be tested. Further research to better define the clinical indications of hemibody irradiation and strontium-89 is recommended.

Radiation sensitive breast cancer patients

Abstract The age dependence of poor cosmesis from breast irradiation and the frequency of micronuclei (MN) in buccal cells provide indirect evidence for the presence of a relatively radiosensitive subpopulation of ataxia telangiectasia (AT) heterozygotes in breast cancer patients

Optimization of box technique to reduce femur dose in radiation therapy of the pelvis

Abstract Using the four field or “box technique” (opposing AP and lateral fields) in irradiating the pelvis, one can reduce the dose to the bladder and rectum while unavoidably irradiating the femurs. Four methods of applying the box technique with 4 MVP, 60 Co, and 24 MVP were analyzed to discover which technique delivers the lowest dose to the femurs: (1) Source-surface distance (SSD) equal given dose to all fields; (2) Source-axis distance (SAD) equal “air” dose to all fields; (3) SSD equal tumor dose to all fields; (4) SAD equal tumor dose to all fields. The results indicate that technique 1 (SSD equal given dose to all fields) gives the lowest dose to the femurs.

Predicting normal tissue injury in radiation therapy

We tested three radiobiologic models, the nominal standard dose (NSD), the biologic index of reaction (BIR), and the linear quadratic (LQ) models to determine which best predicts normal tissue injury in radiation therapy. Clinical data for radiation myelopathy, rib fracture and pericardial effusion were used for all three models to predict injury. We assumed that on the average injuries occurred at higher equivalent doses of radiation than were received by patients who were not injured. We used a t-test to determine whether there were in fact significant differences in the mean values of the equivalent doses among the injured and non-injured. The means were calculated for the four sets of injury by the three models. For the LQ model it was necessary to choose a value for the parameter alpha/beta; the results were not sensitive to the choice over the range of 1/2 to 12 Gy. None of these models showed a significant difference between injured and non-injured patients for all four sets of data. The BIR model showed significant differences in three sets, the LQ model was significant in two and marginally significant in one set, and the NSD was significant in two sets. This analysis illustrates therefore, that the linear quadratic model can be adopted for analysis of clinical data with results that are no worse and possibly better than the NSD model.

Is proton-beam therapy better than intensity-modulated radiation therapy for prostate cancer?

INTRODUCTION Proton-beam therapy (PBT) was first tried at the Lawrence Berkeley Laboratory in 1954, and subsequently as many as 100,000 patients may have been so treated. Then, as now, its rationale is based entirely upon its unique dose distributions, which permit efficacious tumor doses while delivering smaller doses to surrounding normal tissues than can be achieved with x-rays. These qualities would seem to favor PBT for the treatment of prostate cancer (CaP) by reducing gastrointestinal (GI) and gastrourinary (GU) toxicities and the probability of long-term secondary cancers. However, after 20 years of hospital-based experience, there is a dearth of clinical data to show that the 10-year cause-specific survivals or acute and chronic toxicities for patients who received PBT are in any way superior to those treated by intensity-modulated radiation therapy (IMRT).