Unless you live in an area that has native small wild cats, then feral or pet house cats are an invasive species that destroy small mammal and bird populations. And if you live in an area where small wild cats are native, then it’s probably best to not let house cats compete with them and reduce the wild population. There’s really no ecological argument to allow house cats to roam in any environment.
I mean the downsides are basically cost, another stick/blood draw, potential for false positive and further anxiety/testing. No weigh-in on whether or not any individual should at any specific time, but even less-invasive screenings are not zero risk.
Excerpt from the US Preventative Task Force about prostate cancer screening:
“An elevated PSA level may be caused by prostate cancer but can also be caused by other conditions, including an enlarged prostate (benign prostatic hyperplasia) and inflammation of the prostate (prostatitis). Some men without prostate cancer may therefore have positive screening results (ie, “false-positive” results). Men with a positive PSA test result may undergo a transrectal ultrasound-guided core-needle biopsy of the prostate to diagnose prostate cancer.”