Radical radiotherapy for invasive bladder cancer: What dose and fractionation schedule to choose?

PURPOSE: To establish the alpha/beta ratio of bladder cancer from different radiotherapy schedules reported in the literature and provide guidelines for the design of new treatment schemes. METHODS AND MATERIALS: Ten external beam radiotherapy (EBRT) and five brachytherapy schedules were selected. The biologically effective dose (BED) of each schedule was calculated. Logistic modeling was used to describe the relationship between 3-year local control (LC3y) and BED. RESULTS: The estimated alpha/beta ratio was 13 Gy (95% confidence interval [CI], 2.5-69 Gy) for EBRT and 24 Gy (95% CI, 1.3-460 Gy) for EBRT and brachytherapy combined. There is evidence for an overall dose-response relationship. After an increase in total dose of 10 Gy, the odds of LC3y increase by a factor of 1.44 (95% CI, 1.23-1.70) for EBRT and 1.47 (95% CI, 1.25-1.72) for the data sets of EBRT and brachytherapy combined. CONCLUSION: With the clinical data currently available, a reliable estimation of the alpha/beta ratio for bladder cancer is not feasible. It seems reasonable to use a conventional alpha/beta ratio of 10-15 Gy. Dose escalation could significantly increase local control. There is no evidence to support short overall treatment times or large fraction sizes in radiotherapy for bladder cancer

Prediction of infarct size from serial CK determinations: Evaluation by clinical studies and computer simulation

To assess reduction of infarct size by therapeutic intervention, a high predictive accuracy is mandatory. The CK release in the circulation (CKr) was studied in 12 consecutive patients after uncomplicated myocardial infarction, admitted within 5 h after onset of symptoms. Despite improvement of existing methods, such as a more frequent sampling, CK-MB determination instead of total CK determination and use of a gamma-exponential instead of a log-normal curvefitting technique, the correlation between CK, predicted from measurements within 7 h after the start of CK rise and CKr calculated after completion of the CK curve remained poor. Computer simulations were done to investigate measurement errors as a cause of this failure. Normally distributed noise, with standard deviations ranging from 0.2% to 8.0% of peak CK-MB, was added to the first points of an ideal gamma-exponential CK-MB curve and predictions were made from these "noisy" points. A small noise already produced a great variation in prediction: 0.8% noise resulted in a deviation of predicted CKr from calculated CKrranging from -20 to + 6%. It is concluded that adequate prediction of infarct size from serial CK determinations in the first 7 h after onset of the CK rise must fail if the precision of the biochemical determination is not less than 0.4%

Influence of heat and moisture exchanger respiratory load on transcutaneous oxygenation in laryngectomized individuals: a randomized crossover study

High-resistance heat and moisture exchangers (HMEs) have been reported to increase transcutaneous oxygenation (tcpO(2)) values in laryngectomized individuals and to negatively influence patient compliance. The goal of the present study was to validate earlier published results on short-term transcutaneous oxygenation changes by high-resistance HMEs. We conducted a randomized crossover study, monitoring the influence of an HME on tcpO(2) over a 2-hour time interval in 20 subjects. No evidence of an immediate HME effect (95% CI: -14.9-13.3 mm Hg, p = .91), or a time-dependent HME effect (95% CI: -.121 - .172 mm Hg/minute, p = .74), on tcpO(2) was found. After fitting the statistical model without time dependency, again no evidence of HME presence was seen (95% CI: -.5 mm Hg - 3.6 mm Hg, p = .15). In contrast to earlier suggestions, there is no evidence of increased tcpO(2) levels by high-resistance HMEs in laryngectomized individuals. Thus, using such HMEs has no added clinical value in this respec

New insight into rectal function in pediatric defecation disorders: disturbed rectal compliance is an essential mechanism in pediatric constipation

OBJECTIVE: To evaluate rectal sensitivity in patients with pediatric constipation (PC) and nonretentive fecal soiling (FNRFS) using pressure-controlled distention (barostat). STUDY DESIGN: Thresholds for rectal sensitivity (first sensation, urge to defecate, and pain), and rectal compliance were determined using a barostat. RESULTS: A total of 69 patients with PC (50 males; mean age, 10.9 +/- 2.2 years) and 19 patients with FNRFS (15 males; mean age, 10.0 +/- 1.9 years) were compared with 22 healthy volunteers (HVs) (11 males; mean age, 12.7 +/- 2.6 years). Sensitivity thresholds were not significantly different among the 3 groups. Rectal compliance was increased in 58% of the patients with PC (P < .0001 vs HVs). Rectal compliance did not differ between patients with FNRFS and HVs. Children with PC with abnormal rectal function required significantly larger rectal volumes at urge to defecate. CONCLUSIONS: Increased compliance is the most prominent feature in patients with PC. Because of higher compliance in these children, larger stool volumes are required to reach the intrarectal pressure of the urge to defecate. Children with FNRFS have normal rectal functio

Isolated limb perfusion prolongs the limb recurrence-free interval after several episodes of excisional surgery for locoregional recurrent melanoma

BACKGROUND: The influence of isolated limb perfusion (ILP) on the limb recurrence-free interval (LRFI) and the number of lesions per recurrence was studied for patients with frequently recurring regional in-transit metastases previously managed by excisional surgery. METHODS: All 43 patients who had their first ILP for a third or further limb recurrence were selected from our computer database of 451 patients who underwent therapeutic ILP for recurrent extremity melanoma in our centers. Eighteen patients had resectable and 25 had locally unresectable lesions at the time of ILP. The patients had a total of 269 intervals between treatment of their primary melanoma and last recurrence or last follow-up. Median follow-up was 35 months (interquartile range, 14-64 months). RESULTS: The median LRFI decreases over time from primary melanoma to the third or further recurrence for which ILP was performed (P < 0.001). The median LRFI is 4.7 times longer (95% confidence interval [CI], 2.8-7.9; P < 0.001) after ILP in comparison with the last interval before ILP. Patients with resectable lesions have a median LRFI that is 5.9 times longer (95% CI, 2.7-13; P < 0.001). In all patients, the number of lesions increases by 22% per recurrence number (95% CI, 10%-35%; P = 0.02). At the same recurrence number, patients before ILP have a 2.6-fold higher (95% CI, 1.6-4.5) mean number of lesions than do patients after ILP (P < 0.001). CONCLUSIONS: ILP lengthens the LRFI and decreases the number of lesions per recurrence significantly in patients with repeatedly recurrent limb melanoma. Therefore, ILP could be a valuable adjunct to excisional surgery for in-transit metastases in these patients whose LRFIs tend to shorten over tim