Mutahir Ali Tunio

Whole-Pelvis or Bladder-Only Chemoradiation for Lymph Node–Negative Invasive Bladder Cancer: Single-Institution Experience

PURPOSEnWhole-pelvis (WP) concurrent chemoradiation (CCRT) is the standard bladder preserving option for patients with invasive bladder cancer. The standard practice is to treat elective pelvic lymph nodes, so our aim was to evaluate whether bladder-only (BO) CCRT leads to results similar to those obtained by standard WP-CCRT.nnnMETHODS AND MATERIALSnPatient eligibility included histopathologically proven muscle-invasive bladder cancer, lymph nodes negative (T2-T4, N-) by radiology, and maximal transurethral resection of bladder tumor with normal hematologic, renal, and liver functions. Between March 2005 and May 2006, 230 patients were accrued. Patients were randomly assigned to WP-CCRT (120 patients) and BO-CCRT (110 patients). Data regarding the toxicity profile, compliance, initial complete response rates at 3 months, and occurrence of locoregional or distant failure were recorded.nnnRESULTSnWith a median follow-up time of 5 years (range, 3-6), WP-CCRT was associated with a 5-year disease-free survival of 47.1% compared with 46.9% in patients treated with BO-CCRT (p = 0.5). The bladder preservation rates were 58.9% and 57.1% in WP-CCRT and BO-CCRT, respectively (p = 0.8), and the 5-year overall survival rates were 52.9% for WP-CCRT and 51% for BO-CCRT (p = 0.8).nnnCONCLUSIONnBO-CCRT showed similar rates of bladder preservation, disease-free survival, and overall survival rates as those of WP-CCRT. Smaller field sizes including bladder with 2-cm margins can be used as bladder preservation protocol for patients with muscle-invasive lymph node-negative bladder cancer to minimize the side effects of CCRT.

Virtual simulation and treatment verification–merits and demerits: experience at Sindh Institute of Urology and Transplantation (SIUT), Pakistan

Background: The rapid changes in practice of radiotherapy have taken place over the past 5 years in Pakistan. With advent of computed tomography simulator, and multileaf collimators–assisted linear accelerators and electronic portal imaging system, few centres in Pakistan have switched from conventional radiotherapy to modern computer-based technology. Our hospital is first centre in Pakistan which is using virtual simulation since March 2006. We present our experience with list of merits and demerits. Design: Retrospective study. Patient collection: Medical records of all patients who received radiotherapy in our centre were reviewed. Parameters included were type of malignancy, type radiotherapy (curative/palliative), simulation and planning process time and the displacement of the beam-axis from the planning isocentre in clinical situations during three-dimensional conformal radiotherapy using electronic portal imaging device (EPID). Data were collected on written proforma. Percentages, frequencies, measures of central tendency and dispersion were calculated using SPSS version 17.0. Results: A total of 289 patients were treated from March 2006 to November 2008. Transitional cell carcinoma of urinary bladder was most common malignancy seen (42.4%) followed by prostate (28.62%) and renal cell carcinoma (14.14%). Of these 34.26% patients were treated on curative basis. The virtual simulation process could be completed in an average time of 5 min (SD 3.5). Under many cases, the treatment portals could be designed and the patient marked in one session. The displacements were recorded for 43 portals for early prostate cancer using an EPID system. The mean displacement was found 2.44 ± 0.8 mm in x (transverse), y (craniocaudal), and z (anteroposterior) directions during treatment. Standard deviation (SD) was 0.87 (90% CI 2.21–2.66). Average number of portals taken was 10 (6–27) per treatment session. Conclusion: Computer-based simulation and treatment over conventional methods is appropriate for curative patients, achieving more accurate tumour localisation, sparing normal organs at risk, reduced field sizes and a film free environment; however efforts are required to achieve maximum immobilisation during treatment.

In vivo dosimetry with diodes in a radiotherapy department in Pakistan

The International Commission of Radiological Units (ICRU) sets a tolerance of ±5 % on dose delivery, with more recent data limiting the overall tolerances to ±3 %. One of the best methods for accurate dose delivery and quality check is in vivo dosimetry, while radiotherapy is performed. The present study was carried out to test the applicability of diodes for performing in vivo entrance dose measurements in external photon beam radiotherapy for pelvic tumours and its implementation as quality assurance tool in radiotherapy. During November 2007 to December 2009, in 300 patients who received pelvic radiotherapy on a multileaf-collimator-assisted linear accelerator, the central axis dose was measured by in vivo dosimetry by p-Si diodes. Entrance dose measurements were taken by diodes and were compared with the prescribed dose. Totally 1000 calculations were performed. The mean and standard deviation between measured and prescribed dose was 1.26 ± 2.8 %. In 938 measurements (93.8 %), the deviation was <5 % (1.36 ± 2.9%); in 62 measurements (6.2 %) the mean deviation was >5 % (5.51 ± 2.3 %). Larger variations were seen in lateral and oblique fields more than anteroposterior fields. For larger deviations, patients and diode positional errors were found to be the common factors alone or in combination with other factors. After additional corrections, repeated measurements were achieved within tolerance levels. This study showed that diode-detector-based in vivo dosimetry was simple, cost-effective, provides quick results and can serve as a useful quality assurance tool in radiotherapy. The data acquired in the present study can be used for evaluating output calibration of therapy machine, precision of calculations, effectiveness of treatment plan and patient setup.

Influence of catheters on predicted tumour control probability and severity of acute genitourinary toxicity during high-dose-rate brachytherapy prostate boost

Purpose: High-dose-rate brachytherapy (HDR) boost is an effective method for dose escalation when treating prostate cancer. Optimal number and location of catheters play key role in radiation dose delivery. We studied the impact of catheters and associated trauma on the dose uncertainties and urethral toxicity. Methods and Materials: Between July 2008 to August 2009, 50 patients with prostate cancer were treated with 46 Gy of external irradiation of whole pelvis (2 Gy per fraction) and two HDR brachytherapy fractions (each 14 Gy) at the end of 10 fractions of external beam. All brachytherapy implants were planned using real-time, ultrasound-based planning system. Variables were prostate and urethral volumes, number of catheters and their mean distance from base of bladder and dose volume histogram parameters. All data were collected during first implant only. The toxicities were graded according to Radiation Therapy Oncology Group Toxicity Criteria. Statistical analysis was done on SPSS version 17.0. Results: The mean number of catheters implanted was 12.38 (8–19), and number of attempts per needle to achieve desired position was 1.6 (range = 0–5). Mean distance between the catheters tips to contrast filled bladder was 3.2 mm (1–8 mm) after the adjustment. Distances >5 mm showed lower doses to prostate and lower predicted tumour control probability (TCP) ( p p Conclusion: Dose decline and subsequently lower TCP were seen for the greater distances between the needles and bladder. Acute GU toxicity increased with higher urethral, but severity of acute GU toxicity does not increase with increase in prostate/urethral volumes, number of catheters needles and attempts.