Anyone have HER2 3+ DCIS w/mastectomy?

mlrbelle,

For those who have pure DCIS, HER2 results are meaningless and don't impact treatment.  Often DCIS pathology reports don't even include an HER2 reference. 

For women with invasive cancer, HER2+ is an indicator of a more aggressive cancer.  Because of the aggressiveness of HER2+ cancer, these women are almost always given chemo and are treated with Herceptin, which is a very toxic drug. These treatments are given whether a woman has a lumpectomy or a mastectomy.  The only cases where chemo and Herceptin would not be prescribed are when the size of the invasive tumor is very small - smaller than 0.5cm. 

I believe that about 20% of invasive cancer is HER2+.  For some reason, a much higher percentage of DCIS is HER2+; I've seen numbers ranging from 40% to 60%.  No one knows yet why it is that so much more DCIS is HER2+.  It's also not known what it means to have HER2+ DCIS.  There have been some small studies on this but there are no clear results.  One recent study suggested that HER2+ DCIS is more aggressive but another recent study showed the opposite, i.e. that HER2+ DCIS was less aggressive and less likely to become invasive. So at this point, nobody really knows.  There are currently some clinical trials going on to study HER2+ DCIS and to see if Herceptin might be beneficial.  But, except for those who participate in the clinical trial, Herceptin is not approved for DCIS so women who have HER2+ DCIS are not treated any differently than those who are HER2-.  

As for radiation, although there are exceptions, as a general rule it is not necessary after a mastectomy for DCIS (but there can be exceptions if the margins are too close) and as a general rule is it recommended after a lumpectomy for DCIS (here again there can be expections if the margins are extremely wide). 

Chemo, being a systemic treatment (i.e. it is given to treat the risk that cancer cells may have escaped the breast) is not required for those who have pure DCIS, since by definition DCIS cancer cells are completely contained within the breast.  This is the case whether one has a lumpectomy or a mastectomy.

Shelley, I remember when Dr. Czerniecki's study was released - we had some good discussion about it here on the board.  I think that the findings are important and certainly suggest that more research is necessary to determine the effects of HER2 overexpression in women with DCIS.  However what I also remember about the study is that the results were based on a very small sample.  I just pulled up a copy of the study to confirm this.   In total, the tissue samples of 106 women with DCIS were examined; of this group, 39 had HER2 overexpression and 22 had microinvasions.  So even if the results of the study were very clear, it is not reasonable to draw definitive conclusions for the population as a whole (i.e. all women with HER2+ DCIS) based on such a small sample. More research, using a larger sample of women, is necessary.  While I don't question the results of Dr. Czerniecki's study, I simply wouldn't want women reading this who have HER2+ DCIS to panic or react based on the findings of one small study. 

Additionally, as I mentioned in my previous post, there have been other studies that have concluded the opposite of what Dr. Czerniecki found.  One study that looked at samples from 100 women with pure DCIS and 100 women with DCIS with microinvasions concluded that "HER-2/neu gene amplification was inversely associated with the risk of invasive progression in DCIS patients".  The authors of this study go on to say that "it is possible that HER-2/neu stimulates growth during the in situ phase only, and promotes differentiation and growth inhibition as the lesion progresses to invasive cancer."

For anyone interested, here is information about Dr. Czerniecki's study:  http://esciencenews.com/articles/2009/05/22/protein.predicts.development.invasive.breast.cancer.women.with.dcis.penn.study.shows

And here is information about the other study that I referenced: http://cebp.aacrjournals.org/content/11/6/587.full

Lastly, here is a very interesting article comparing the results of two other studies on HER2 overexpression in DCIS, each with different results: http://journals.lww.com/oncology-times/pages/articleviewer.aspx?year=2007&issue=04250&article=00016&type=fulltext   The overall conclusion seems to be that we simply don't know yet what it means to have HER2+ DCIS and more research is necessary.  The good news is that this research is continuing with doctors like Dr. Czerniecki and others.

mlrbelle, how did your meeting with the oncologist go?