Late chest wall toxicity after MammoSite breast brachytherapy.

PURPOSE: Accelerated partial breast irradiation (APBI) with the MammoSite breast brachytherapy (MBB) system is being investigated as an alternative to whole breast radiation in breast conservation therapy (BCT) at multiple centers worldwide. The newness of MBB means a complete understanding of long-term toxicity, particularly involving the chest wall, has yet to be completely articulated. We report the first pathologic rib fractures associated with MBB and dosimetric analysis of the original treatment plans. METHODS AND MATERIALS: As part of ongoing quality assurance, we reviewed the records of 129 sequential patients who underwent MBB for breast cancer and identified those who subsequently had clinically significant and radiographically documented rib fracture(s) involving the ipsilateral chest wall. Equivalent tolerance doses yielding a 5% and 50% risk of rib toxicity within 5 years from treatment with 10 fractions (as with MBB) were previously calculated using the linear quadratic equation based on 2Gy per fraction treatments delivered to one-third of the rib volume (TD5/5=37Gy; TD50/5=44Gy). The original radiation therapy plans were evaluated vis-à-vis the plane films or PET/CT images documenting the osseous abnormalities and presenting complaints to find the specific fractured ribs. The specific effected ribs were contoured on the planning CT in "bone windows" using the Nucletron MicroSelectron-classic V2 (Nucletron B.V., Veenendaal, The Netherlands) for this analysis and the original patient treatments. With these datasets, we determined the dose-volume characteristics of the effected ribs including maximal dose encompassing the entire rib on one CT slice, V(20Gy), V(30Gy), V(37Gy), V(44Gy), D(50), D(25), and D(5) (the mean dose to 50%, 25%, and 5% of the rib). RESULTS: Between May 2002 and August 2007, three of 105 patients with a minimum of 6-months follow-up who underwent adjuvant APBI by MBB were found to have a total of five treatment-related rib fractures. The average dose-volume characteristics from the original plans were as follows: D(50)=22.1Gy, D(25)=32.2Gy, D(5)=41.6Gy, max dose to 1cc=34.8, D(max) (to 0.1cc)=45.6Gy, V(20)Gy=57.4%, V(30)Gy=30.8%, V(37)Gy=15.9%, V(44)Gy=6.6%, and max dose through rib=35.8Gy. Two patients sustained two rib fractures and 1 patient had a single rib fracture. Four of five fractures occurred in postmenopausal patients and two of five fractures occurred in a patient with a history of osteoporosis and exposure to adjuvant chemotherapy. CONCLUSIONS: Fractures occurred in ribs with V(37)Gy and V(44)Gy each well below 33%. As long-term toxicity data accrue from APBI series, the traditional models for estimating the biologic equivalent dose may benefit from refinements that specifically address the unique radiobiologic and physical properties intrinsic to high-dose-rate brachytherapy for breast conservation therapy.

Rectourethral fistula after combination radiotherapy for prostate cancer.

OBJECTIVES: To describe 6 cases of rectourethral fistula in patients treated with brachytherapy plus external beam radiotherapy for localized prostate cancer and subsequent rectal biopsies or rectal surgery. METHODS: A retrospective chart review was undertaken of patients with prostate cancer treated with brachytherapy who presented to our institution with the diagnosis of rectourethral fistula from February 1999 to June 2002. Potential contributing factors, including patient age, cancer grade and stage, cancer treatment, rectal procedure, and time to the complication, were evaluated. Potential approaches to rectourethral fistula treatment and their outcomes are reported. RESULTS: The mean patient age was 63.8 years. All 6 men underwent combination prostate brachytherapy and external beam radiotherapy with subsequent rectal biopsy/hemorrhoidectomy. All 6 patients developed a rectourethral fistula, with an average time between the end of radiotherapy and fistula development of 22.6 months. Four patients underwent hyperbaric oxygen therapy, which failed. Three patients underwent fecal diversion with gracilis interposition flaps, and two underwent pelvic exenteration. CONCLUSIONS: The results of our study have shown that rectourethral fistula development is a serious complication of combination radiotherapy, with definitive repair requiring major intraabdominal surgery. Biopsy of rectal ulcers in the clinical setting of combined radiotherapy should not be performed. In addition, elective rectal surgery should not be performed on irradiated tissue. In our series, hyperbaric oxygen therapy and conservative treatment did not obviate the need for definitive surgical management of the rectourethral fistula.

Radiation necrosis masquerading as late tumor recurrence: 14 years after combined fractionated stereotactic radiosurgery and conventional radiation therapy.

Radiation necrosis is a known sequela of delivering high doses of ionizing radiation to the central nervous system and may be confused with tumor recurrence. Although stereotactic radiation has found increasing application in managing central nervous system malignancies, the imaging appearance of benign tissue several years after such treatment has not been frequently documented in the medical literature. We present the imaging and pathologic features of brain tissue that received fractionated stereotactic radiation by linear accelerator fourteen years earlier.

Incidence and patterns of neuraxis metastases in children with diffuse pontine glioma.

PURPOSE: We performed a retrospective study of patients with diffuse pontine glioma (DPG) who suffered neuraxis metastasis (NM) and characterized the incidence, clinical features, radiologic findings, and patterns of disease dissemination. METHODS: Magnetic resonance imaging (MRI) of brain and spine was used to assess NM. Some patients also underwent magnetic resonance spectroscopy (MRS) (6 patients) and fluorodeoxyglucose positron emission tomography (FDG-PET) scans (13 patients) to further evaluate areas of metastatic disease. Three patients had histologic confirmation of disease at the site of NM. RESULTS: Between 1986 and 2003, 18 of 96 patients (17.3%) with DPG developed NM. The median age at diagnosis was 8 years (range, 4-17). All patients had adjuvant chemotherapy and/or focal radiotherapy at diagnosis. The NM occurred at a median of 15 months from diagnosis of DPG (range, 3-96). Three patterns of NM were seen on MRI of brain and spine in these patients; 8 (39%) had parenchymal (PM), 4 (22%) leptomeningeal (PM), 2 (11%) subependymal, and in 5 a combination of two or more patterns. The MRS and FDG-PET scan of suspected areas of metastatic disease was consistent with tumor in 6 of 6 and 12 of 13 patients who underwent these procedures respectively. Three patients also had histologic confirmation of malignant glioma at the site of NM. Despite salvage therapy, all 18 patients have died of disease at a median of 5 months (range, 0.5-20) from diagnosis of neuraxis spread. CONCLUSION: Our study emphasizes the need for screening patients with DPG for NM at the time of recurrence.

Renal cryoablation and radio frequency ablation: an evaluation of worst case scenarios in a porcine model.

PURPOSE: Although ablative technologies, including radio frequency (RF) ablation (RFA) and cryoablation (CA), are being used to treat renal masses, complications associated with injury to vital renal structures are not well understood. We investigated these worst case scenarios by deliberately targeting vital renal structures with CA or RFA in a porcine model. MATERIALS AND METHODS: Following surgical exposure of the right kidney in female pigs a cryoneedle or an RF probe was deliberately placed under visual and ultrasound guidance in the renal pelvis (CA in 5 pigs and RFA in 7), major calix (CA and RFA in 5 each) or subsegmental renal vessels (CA in 5 pigs and RFA in 7). Cryo-energy or RF energy was then applied to create a 3 cm lesion. After 10 days the kidneys underwent gross and histological examination for urine and blood extravasation, cell death and injury. Ex vivo retrograde pyelography was performed to evaluate for urinary fistulas. RESULTS: All pigs tolerated the treatment and no procedure related deaths occurred. No significant bleeding was noted. RFA and CA created reproducible lesions and areas of cell death and necrosis. Despite significant intentional injury to the collecting system no urinary fistulas were demonstrated in CA specimens (0 of 15). In contrast, damage to the renal pelvis (4 of 7) by dry (3 of 4) or wet (1 of 3) RFA was associated with a high likelihood of urinary extravasation. CONCLUSIONS: This short-term study demonstrates that CA is safe, effective and not associated with urinary extravasation. In contrast, RFA to the renal pelvis is associated with urinary extravasation. Further studies are needed to support these findings.

Does prior benign prostate biopsy predict outcome for patients treated with radical perineal prostatectomy?

OBJECTIVES: To determine the effect of prior benign prostate biopsies on the surgical and clinical outcomes of patients treated with radical perineal prostatectomy for prostate cancer. METHODS: A total of 1369 patients with clinically localized prostate cancer underwent radical prostatectomy by a single surgeon between 1991 and 2001. A subset of 203 patients (14.9%), who had undergone at least one prior benign prostate biopsy for a rising prostate-specific antigen and/or abnormal digital rectal examination, constituted our study population. A total of 1115 patients with no prior biopsy represented our control group. After prostatectomy, patients were evaluated at 6-month intervals for biochemical evidence of recurrence, defined as a prostate-specific antigen level of 0.5 ng/mL or greater. RESULTS: Patients with a prior benign biopsy had more favorable pathologic features with more organ-confined (74% versus 64%; P <0.001) and less margin-positive (9.8% versus 18%) disease. Only 24 patients (12%) in the study group (versus 20% in control group; P = 0.01) had eventual evidence of biochemical failure. Kaplan-Meier analyses suggested that patients with prior benign biopsies have improved biochemical disease-free survival, especially for those with more aggressive disease (Gleason sum 7 or greater; P <0.01). Overall, patients in the study group had lower probability (odds ratio 0.57, P <0.001) of biochemical failure compared with those in the control group. CONCLUSIONS: A prior benign prostate biopsy may be independently associated with more favorable surgical and biochemical outcomes after prostatectomy. Additional studies are needed to confirm these findings.