Aim: To evaluate the potential contribution of a fluorescent in situ hybridization (FISH) as prognostic indicator of the risk of recurrence or progression in patients undergoing follow-up for non-muscle-invasive bladder cancer (NMIBC).
Patients and methods: A total of 126 consecutive patients with a history of NMIBC being followed-up with urinary cytology and cystoscopy at a referral centre were studied. Patients with carcinoma in situ, or tumour stage higher than pT1 were excluded. A UroVysion FISH kit was used to detect four chromosomal abnormalities, specifically, locus 9p21, Ch 3, 7, and 17. Three FISH patterns were defined: negative; low-risk positive, i.e. positive staining for 9p21 and/or Ch3 abnormalities; and high-risk positive, i.e. positive staining for Ch7 and/or 17.
Results: Overall 73 out of 126 patients (57.9%) had a positive urinary FISH test. After a median time of 14 months, 46 FISH-positive patients underwent recurrence (36.5%) and in 15 patients there was progression of disease (11.9%). Among positive patients, the low-risk category was found in 34, and the high-risk in 39. Low-risk FISH-positive patients had a higher rate of recurrence as compared to FISH-negative patients, with a hazard ratio (HR) of 1.6. The recurrence rate was even greater in patients with a high-risk positive test, with an HR of 1.9. The limitation of the study was that the impact of intravesical treatment was not assessed.
Conclusion: The urinary FISH test can be used as an aid in predicting the risk of recurrence during follow-up of patients with history of NMIBC.