Positive Colon Cancer Screening Test

Summer91

All, my husband has Stage 4 prostate cancer. After radiation therapy for the tumor in the prostate and for lesions in his bones plus being on Xtandi and Lupron, his past 3 PSA tests have come back with non-detectable levels. That is good news! His primary care doctor wanted him to take the Cologuard (colon cancer screening) test. All of his previous screenings for this cancer have been negative. This is the first screening he has had since the radiation/drug therapy for prostate cancer and the result came back positive. I know that Cologuard has a notoriously high false positive rate but I am wondering what impact the radiation therapy may have had on the lower bowel. Anyone had a similar experience? He is scheduled for a colonoscopy in a few weeks.

VascodaGama

I never heard nor think that the radiotherapy for PCa could initiate colon cancer in such short time. Probably it is a false positive as you suggest.

Best wishes for continued remission status.

VG

Summer91

https://csn.cancer.org/discussion/comment/1694175#Comment_1694175

Thanks for the comment. His radiologist said that the radiation can leave behind residual blood. However, it has been almost 1 1/2 years since the radiation so I suspect it is the very common false positive.

Old Salt

I suspect that the blood is due to damage to the intestinal wall caused by the prior radiation. These sorts of things can happen after radiation. It's called radiation proctitis (rectal bleeding). Sometimes the issue will go away on its own. My problem was solved with argon plasma coagulation (APC); a procedure that can be done during a colonoscopy.