I don't think you'll ever know. If I was you I would try and forget about it as it's not worth getting wound up over. If she truly had cervical cancer I think as standard they do a total abdominal hyst with removal of ovaries and lymph nodes.
I know some that lied about having cancer, they used it as a tool to keep their partner. They kept it up for months. Eventually I emailed the MIL and said it started out as this cancer, then it changed, then it took 6 months to be operated on. The best part was they claimed that the cervix was moved by keyhole surgery in the tummy. No hyst, just no more cervix.
I'm no expert but I think you need your cervix to stop your womb hanging down by your knees. Other lies were daft too, they know they'd been caught out.
It's her mess, think of her poor children and family. That was my focus, the woman would be all, won't have my chemo I'll just die. Apparently she was having it every day in tablet form, but again I've had chemo type drugs for autoimmune stuff, the chemo one that's used as chemo is a once a week drug. Not TDS.
She has issues if she is lying, just don't engage. Maybe call school and say you're worried about the child/ren, with her having cancer. Should we try and do a fundraiser for her, it must be hell on the DC. That should sort it out. My DC have support as I'm disabled, they have something through SEN/SED where they speak to a counsellor as I'm that ill. Although they have varying forms of help depending on the DC. As my disability is severe and as it is likely I might not see them get their GCSE's etc, they make sure that they put in as much as possible.
During the holidays we had SS & HA round, SS wanted to sort out care etc, HA wanted to get me on list for suitable housing. They wanted to speak to both DC as SS have support groups and camps etc.
It depends if you just want to ignore it, or whether you want it to stop for the sake of DC.