Aromatase Inhibitor or Tamoxifen?

[Kaye...]

I was dx'd w/invasive lobular--2.5 cm tumor 9 mos. after I had a supposed normal mammogram.  I had bilateral mastectomy (one side prophyllactic) because of very bad family hx of breast cancer.  Although I tested negative for the gene, I was told that all genes have not yet been identified and that there was still good chance there was genetic base.
In addition to invasive lobular, they found DCIS w/comedo necrosis and there was a separate tumor in the nipple with dermal lymphatics and was told that I may indicate that I also have inflammatory breast cancer and am considered in the "gray" area for that.  There were 9 positive lymph nodes with lympho-vascular invasion.  All margins were clear although distance from main tumor was .6 cm from deep margin.  I was both ER and HER2+.  Supposedly, only 5% of those w/invasive lobular are HER2+.  After surgery, all scans were clear.
I have had 4 cycles of AC, then 5 weeks of radiation and then 4 cycles of a taxane (2 Taxol and then 2 Taxotere) along with weekly Herceptin which I will receive for a year.  Tamosifen was originally recommended as the next step in treatment, although I've been told that an aromatase inhibitor would be an okay choice as well.  My understanding is that latest research has shown that Tamoxifen is less? or not? effective in those who are HER2+  I have also read contradictory research about one of the aromatase inhibitors being effective in those who are HER2+  One report said it was effective and had a good response rate and another report on different research that said it wasn't. Both of those contradictory studies were done on Letrozole or Femara.   I am wondering if I should even take hormonal therapy, and, if so, what to use--Tamoxifen or an aromatase inhibitor, and if the latter, which one?

[CCF-RN,MSN-rf]

Dear kaye:  Currently, the standard of care for situations like yours is chemotherapy + tamoxifen.  In general, the tamoxifen would be given just after chemotherapy is completed.  Both aromatase inhibitors and herceptin have been approved for advanced disease but not in the adjuvant setting.  There have been clinical trials of aromatase inhibitors in the adjuvant setting and the data are encouraging.  Aromatase inhibitors are indicated for post-menopausal women only.  There are also clinical trials on-going testing herceptin in the adjuvant setting.  Perhaps you are on one of these studies.  If you are on a trial for herceptin, the trial protocol would dictate when tamoxifen should commence.

[Kaye...]

Although the standard of care may still be Tamoxifen, the most recent studies are showing that Tamoxifen appears to be minimally effective in those who are HER2+ (as well as ER+) and that aromatase inhibitors may be more effective.  This past week the compamny that makes both Tamoxifen and Arimedex has been given notice that their request to have Arimidex approved for use in the adjuvent setting for, I believe, use with post-menopausal in the early treatment setting has been given fast track status.   (I am not sure if I am stating that quite right).  Also, many oncologists have been switching their patients, particularly if they are both ER+ and HER2+, from Tamoxifen to an aromatase inhibitor.  I have read this both on-line on breast cancer support forums and talked with women in our community who are in breast cancer networking group.
As far as use of Herceptin--although my initial pathology report was IIb, my oncologist is treating me out-of-protocol because he feels that my type(s) of cancer are very different than the standard which I believe is allowed.  Because of the strong possibility of an inflammatory component, he feels the clinical staging suggests III(b).  I would have participated in the clinical trial re use of Herceptin in the adjuvent setting for those whose b.c. for those at my pathological stage but was rejected because of a prior existing neurological condition that would have possibly exacerbated side effects from the other medication involved (Taxol).

[CCF-RN,MSN-rf]

Kaye:  You are correct in your evaluation of the research to date.  Aromatase inhibitors do show promise in the adjuvant setting in folks who are her2 positive.  However, on an internet forum, we cannot recommend therapies that are not approved.  Physicians may elect to treat patients "off protocol" but this is a decision that has to be made on an individual basis, taking into account everything about that patient, including history and physical examination.  It also means taking responsibility for any ill effects, short term or long term, that may not yet be known.  We simply cannot make such recommendations on an internet forum.