HER2+ stage at diagnosis

mochiepie, I don’t know of any data that matches exactly what you’re asking but I can tell you that about 20% are HER2 + and since it is more aggressive than other types It’s not surprising that you’d find it more frequently with higher stages. But this is just my guess from personal experience, I had a clear mammogram about a year 1/2 before diagnosis and my tumor grew fast, appearing seemingly overnight.

The flip side to HER2 is that although aggressive, the medications to treat it typically work very well and for several years. There’s lots of research in HER2 and more options down the line.

The other thing that invalidates many numbers of "early" is that docs don't test for HER2+ with DCIS . I had DCIS (which was at the time considered cancer, albeit early stage). Then I had a "local recurrence" in 2 years that had morphed into IDC and HER2+. Was I HER2+ all along? We'll never know. I think they still don't test DCIS patients for HER2.

MinusTwo- My DCIS was tested for her2 last year (it was her2+). Not sure if it was standard protocol or if my surgeon specifically requested it. Going into my BMX, all they could find via biopsies was DCIS. My post surgery pathology reviled the IDC (we figured it was there somewhere due to my DCIS size). My 3mm of IDC that was found on a node was also her2+. Interestingly my DCIS was er/pr- and my IDC was highly er/pr+.

To add to this discussion, the reason DCIS isn't usually tested for HER2 status is because there have been dozens of studies (all small, mind you) and they have yet to determine if being HER2+ has any bearing on DCIS. A few studies have suggested that HER2+ DCIS might be more aggressive and more likely to develop into invasive cancer, but a few studies have found the opposite, which is that HER2+ DCIS might be less likely to develop into invasive cancer. Most studies found no difference in aggressiveness or prognosis.

Interestingly, whereas approx. 15%- 20% of invasive cancers are HER2+, approx. 40% of DCIS diagnoses are HER2+ (and I seem to recall one study that found 60% to be HER2+). Logically, if HER2+ DCIS is aggressive and more likely to develop into invasive cancer, then one would expect a higher percentage of invasive cancers to be HER2+, not a lower percentage. The reason for this strange disconnect has yet to be discovered.

In addition to not knowing what HER2 status means for DCIS, there are no meds for HER2+ DCIS. Herceptin is not approved for DCIS. Because HER2 invasive cancer is so aggressive, it logical for patients to assume that HER2+ DCIS is also aggressive. For the few with DCIS who do find out their HER2 status, if they discover that they are HER2+ and then learn that there are no treatment differences vs. HER2- DCIS, usually this causes great concern and often this concern lingers years beyond treatment.

For research purposes and for future knowledge, I wish that all DCIS was tested for HER2 status - one day we may understand the significance and then this might be something important to know. But personally I was happy not knowing the HER2 status of my DCIS back at the time of my diagnosis (and I had a microinvasion of IDC, which also wasn't tested, as was common 15 years ago).

This is why illimae's data (very interesting!) that shows invasive cancer stages only, is appropriate when assessing HER2.

illimae - I am rooting for you, yay for 50 months and many more!