Über die Beziehungen der Leukämie zu geschwulstbildenden Prozessen des hämatopoetischen Apparates

Ohne ZusammenfassungVortrag mit Demonstration von Präparaten und Projektionsbildern, gehalten in den akademischen Fortbildungskursen in Hamburg, am 26. Juli 1913.     

Sensitivity of treatment plan optimisation for prostate cancer using the equivalent uniform dose (EUD) with respect to the rectal wall volume parameter.

BACKGROUND AND PURPOSE: To analyse the sensitivity of plan optimisation of prostate cancer treatments with respect to changes in the volume parameter (n), when the EUD is used to control the dose in the rectal wall. PATIENTS AND METHODS: A series of plans was defined, by varying n over a range between 0.08 and 1, and testing different cost functions and beam arrangements. In all cases, the aim was to minimise the EUD in the rectal wall, while ensuring specific dose coverage of the PTV, and limiting the dose in the other OARs. The results were evaluated in terms of 3-D dose distribution and with respect to the current clinical knowledge about late rectal toxicity after irradiation. RESULTS: Different values of n lead to very similar dose distributions over the PTV (differences in mean dose < 1 Gy, differences in dose given to 99% of the volume < 1%). For the rectal wall, the following observations were made: (a) all cumulative DVH curves crossed each other around 60 Gy; (b) the rectal wall volume receiving doses between 30 and 45 Gy could change by 45 and 30%, respectively, depending on the value of n; (c) for doses higher than 70Gy the differences were typically within 5%. Different values of n also affected the position of isodose surfaces. The distance between the 70 and the 30 Gy isodose curves changed in the AP direction by a factor of 3 when n decreased from 1 to 0.08. High values of n were associated with less dose conformity and a larger volume (at least 20%) of normal tissues receiving 50 Gy or more. All DVHs for the rectal wall were below published dose toxicity thresholds except when the prescribed dose was escalated up to 86 Gy. CONCLUSIONS: In most cases, the solutions associated with n values up to 0.25 produced similar dose distribution in the rectal wall for doses above 45 Gy, complying with the dose-toxicity thresholds we analysed. The choice of a specific value of n in the optimisation requires an analysis of its effects on the dose distribution for the rectal wall, but also on other aspects, such as the value of the dose to the non-involved normal tissues.     

The influence of early steroid withdrawal on body composition and bone mineral density in renal transplantation patients

Corticosteroid treatment may have an important effect on body composition and bone mineral density (BMD) in renal transplantation (RTx) patients. We investigated the effect of early steroid withdrawal on body composition and BMD of RTx patients in a prospective design. Post-transplant immunosuppression consisted of tacrolimus, mycophenolate mofetil, and prednisolone. Three months after RTx, 27 patients participating in a multi-center trial were randomized either to continue steroids (at a dose of 10 mg/day, n=17; steroid+) or be withdrawn from steroids within 2 weeks (n=10; steroid-). Body composition and BMD (lumbar spine (L2-L4) and femoral neck) were measured by dual-energy X-ray absorptiometry (DEXA) just before and 3 months after randomization. With regard to body composition, fat mass tended to increase in the steroid+ group (1.1+/-2.3 kg; P=0.084), but did not change in the steroid- group. Increase in body fat percentage tended to be higher (P=0.08) in the steroid+ group (0.6+/-2.7%) than in the steroid- group (-0.7+/-2.1%). The change in lean body mass was not significantly different between the two groups. BMD of the lumbar spine and femoral neck decreased significantly in the steroid+ group (-1.4+/-3.2% and -2.3+/-2.9%, respectively, P<0.05) while no changes were observed in the steroid- group. The change in BMD of the lumbar spine was significantly different between the steroid+ and the steroid- group, whereas the change in BMD of the femoral neck was not significantly different. Thus, the increase in fat mass tended to be higher in the group continuing on steroids, though not significant, due to large inter-individual variation. In general, the effect of early steroid withdrawal on body composition after RTx appears to be modest. In addition, early steroid withdrawal seems to have beneficial effects on BMD in RTx patients, especially in the lumbar region.