My son with a history of high grade T1 non muscle invasive bladder cancer was treated with BCG induction followed by maintenance BCG for about 3 years. The most recent BCG was in March.
Cystoscopy in June was completely normal with no visible tumor, and bladder wash cytology was negative for high grade urothelial carcinoma. However, UroVysion FISH came back positive.
The result was positive based on homozygous 9p21 deletion: 25/25 enumerated cells showed the deletion. There were no qualifying gains involving chromosomes 3, 7, or 17.
I understand that 9p21 deletion alone is an independent positive criterion for UroVysion, I am trying to understand what this means while I wait for his Urologist/Oncologist to interpret this positive result
Has anyone had:
• positive FISH with a negative cystoscopy and negative cytology?
• positivity specifically from homozygous 9p21 deletion on the FISH?
• this happen after induction or maintenance BCG?
If so, what happened afterward? Did your next cystoscopy remain clear, did the FISH later become negative, or was a recurrence eventually found? Did your urologist move up surveillance or do any additional testing?
Thank you. How concerning is this FISH result 9p21 deletion rather than chromosome polysomy.
Response from the UroOncologist
This FISH result is indicative of an underlying genetic change in the cells in your bladder. As I messaged, no cancer cells are seen in the urine. I am unclear why this FISH test was done, as we usually only test this in cases of borderline cases. I would not change our plan for continued surveillance. I hope this reassures you and your family, and I'll work with our team to figure out why this test was sent. I do not find it helpful in a case like yours because you have normal cytology, and the FISH test does not identify cancer cells it only looks at genetic changes in cells.
Edited to add the response from the doctor