If 61 yr m had a -ve whole body pet+ct done for renal mets 1 yr ago, how long we can postpone colonoscopy (first time)screening for colon cancer?

You shouldn't : Although a pet ct will show some types of cancers and is part of a metastatic work up, it will not detect precancerous polyps and can miss small cancers. I would recommend a screening colonoscopy.

Let me be: Sure i understand. She had a renal cancer removed, and that was more than a year ago, and pet showed no metastasis. She is asymptomatic and feeling well? There are advisories that colonoscopy should be done once each decade after 50. She would seem eligible for that, but there is no rush.

Please get the : Screening colonoscopy. Pet/ct should see a large colon cancer, but small cancers and polyps could be missed, and physiologic colon activity can obscure colon cancer as well. Optical colonoscopy should be performed at age 50 and every 10 years thereafter for colon cancer screening.

Have colonoscopy now: In case you’re wondering any relationship between RCC or colon cancer etc. There is no such unless the RCC metastasized to colon. You had a negative CT for mets so you probably had stage I or II RCC & your likelihood of 5-year survival rate > 90 % [stg I] 75- 95 %[stg II].Usually colon cancer screening should start at 50.Since you had none before you should have one now like any other person