There's a big importance placed on CA125 by women affected by ovarian and some womb cancers. It's like a little flashing beacon that gives us an insight into what's going on in our bodies. Or so we think. I am beginning to discover it is more complicated than that.
CA125 is a blood protein that is present in many ovarian and ovarian-type cancer cells in higher concentration than normal cells. But it is also present in many other benign conditions, such as endometriosis. It can rise where there is inflammation. So by itself, a raised CA125 is not a useful cancer diagnostic measure but a possible indicator that cancer might be present.
In women with advanced ovarian-type cancers, levels of CA125 can go up and down as the cancers grow and shrink. So it is often used as a marker - doctors measure the CA125 to see how the levels change over time. But the importance to attach to a given number is unclear.
Back in May my CA125 started to climb and it seemed that the rucaparib was starting to fail. My initial thought was that the cancer had started to grow again and my time on the drug would be limited. My consultant agreed as much and raised my dose to see if that would knock it on the head. But the CA125 continued to go up and she warned me at the start of the summer that she reckoned I had two, maybe three months left on rucaparib. It was, if I am honest, a blow as I had pinned so much hope on getting a larger window.
In August, I had a scan. Both Dr K and I were expecting to see tumour growth compared to the previous scan in April (Or was it February? These dates get mixed up sometimes). But no. The tumours had continued to shrink. Happy days! Dr K explained that a tiny number of drug-resistant cells can cause a rise in CA125 and drew me a U-shaped curve of tumour growth against time. The scans had likely captured images either side of the base of that U (when the tours were at their smallest). It was an elegant exercise in managing expectations. But for the meantime, another two months on the Rucaparib. OK, with the higher dose the fatigue and nausea have been fairly grim but there's "no free ride with cancer" as someone wiser than me has said.
I saw my docs again yesterday. The CA125 continues to go up but it's a steady increase rather than a massive jump with an added 20 points each month (its now 135 compared to a low of 22 in April). The registrar I saw yesterday was not overly concerned by this, saying a slowly rising CA125 does not tell them too much. It's too soon for a scan, he reckoned, as we'd not likely see enough change to measure. So another two months and back in December with a plan to to another scan.
Now. This is all good news, in the scheme of things. My doctors are very reassuring about the importance they attach to CA125. The message I have received is that it is the least important of three measures. Most important is how I feel, second is what the scan shows and CA125 comes third. But there are a couple of glitches.
First, I appear to have fallen down a black hole into the slough of despond. It is hard managing the uncertainty and living with the side effects which limit my energy and capacity to do things I want to do. I am now paying attention to this.
Second, what I am hearing about CA125 is very different to what other women are hearing. I've chosen to cling to what my doctors have said and believe them. But I am in touch with other women with a similar pattern of rising CA125 while on a PARPi to me and whose doctors are giving "very worried" messages. They are in a panic as a result. That does not seem to me be very helpful.
