[930] Lack of FISH Abnormalities in Bladder Biopsies from Patients with History of Pelvic Radiation: A Pilot Study.

Kandelaria Rumilla, Michael Campion, Trynda Oberg, Jesse Voss, Jun Zhang, Kevin Halling, Thomas Sebo. Mayo Clinic, Rochester, MN

Background: Radiation therapy is part of the clinical armamentarium used to treat pelvic malignancies in men and women. The radiated field often includes the bladder and may induce mucosal alterations which can be mistaken in urine cytology specimens and bladder biopsies for urothelial cancer. We conducted a pilot study to investigate whether FISH abnormalities were detected in patients with bladder biopsies exhibiting radiation treatment effect.
Design: 17 bladder biopsy samples from 14 patients who have undergone radiation therapy for prostate, bladder, rectal, cervical or ovarian cancer were selected. Of these, 13 were benign and 4 contained urothelial cancer (2 high-grade, 2 low-grade papillary). Of these 4, 3 were from patients with a corresponding benign biopsy. Specimens were analyzed using FISH probes targeting the centromeric regions of chromosomes 3, 7, 17 and the 9p21 locus. Signal patterns were recorded for 50 non-consecutive transitional cells. Specimens were considered positive if ≥5 cells were polysomic cells (gains in ≥2 probes), ≥10 cells were trisomy (three signals in one of the probes) or ≥20 cells showed homozygous 9p21 loss (zero copies of 9p21 probe). Correlation with the pathologic diagnosis and clinical history was performed.
Results: The 13 benign specimens were all FISH disomy (negative; 100% specific). In the 4 biopsies with cancer, the 2 high grade cancers were polysomic and homozygous for loss of 9p21; and the two low grade papillary cancers were FISH negative.
Conclusions: Our pilot study failed to detect FISH abnormalities in benign bladder biopsies from patients who had previously undergone radiation in which the radiation field included the bladder mucosa. In biopsy specimens from patients with flat urothelial atypia subsequent to radiation, FISH may help distinguish between radiation cystitis and urothelial carcinoma. We are currently evaluating FISH in urine specimens from patients with a history of radiation to assess the role of FISH when cystoscopy identifies worrisome areas of mucosal erythema.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 2:15 PM

Platform Session: Section A, Monday Afternoon


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