Bilateral Mastectomy and Ovary Removal - Herceptin and Tamoxifen Really Needed?

I am 35 years old and had a bilateral mastectomy performed 2 weeks ago after a needle biopsy of a tumor in my right breast identified infiltrating lobular carcinoma and DCIS (no family history of breast cancer). A sentinel node biopsy was performed at the time of surgery and the 7 nodes removed were negative (one of the nodes had traces of breast tissue with a 0.1 mm growth that was deemed as benign). Results from the pathology report identified my breast tumor was 1.3 cm, ER/PR positive and HER-2 positive; no other traces of cancer.  A cat scan showed a couple of spots on my lungs that looked "suspicious" per the write up, but were noted to be likely nothing per my oncologist.
My oncologist is recommending chemo (likely 8 sessions every 2 weeks)then Herceptin weekly for a year, followed by ovary removal, and Tamoxifen for 5 years. I have 2 main questions...
1-Based on my smaller tumor size, being node negative, and non-metastatic, I do not think recent discoveries on Herceptin apply to me (the risks seem to outweigh the benefits in my case); I prefer to do the chemo but without Herceptin - will such a decision increase risk for reoccurence?
2-Is the Tamoxifen really necessary since I have had the bilateral mastectomy already performed and will also be removing my ovaries? It is my understanding that the benefits Tamoxifen would offer are of little extra value to a cancer that is most likely cured by mastectomy alone. Also, I believe the most recent Food and Drug Administration approval for Tamoxifen is for women after lumpectomy and radiation (not mastectomy).

[CCF-RN,MSN-JS]

Dear Andama, Herceptin is a monoclonal antibody which works by targeting the HER2/neu receptor on cancer cells. The HER2 gene produces a protein receptor on the cell surface that signals normal cell growth by telling the cell to divide and multiply. Some cancerous breast tissue has too much HER2 (HER2/neu overexpression), triggering the cells to divide and multiply very rapidly. Herceptin attaches to the HER2 receptors to prevent cells from multiplying, preventing further cancer growth and slowing cancer progression. It may also work by stimulating an immune mechanism.  Herceptin has been FDA approved for the treatment of metastatic breast cancer.  Recent studies have shown a benefit to the addition of Herceptin to standard chemotherapy in the treatment of Her2neu overexpressing operable breast cancer.  The two U.S. trials which were analyzed together included mostly patients with lymph node positive disease while a European study included patients with both lymph node-negative and node-positive disease.  Both studies demonstrated a significant benefit to the Herceptin at the cost of a small increase in the risk of serious cardiac side effects.
Tamoxifen is approved for breast cancer treatment in all stages.  While in the treatment of DCIS (without invasive cancer) tamoxifen is often reserved for patients with breast conservation to reduce the risk of recurrence in the breast, it's primary role in invasive breast cancer is to improve survival by reducing the risk of developing metastatic disease (similar to the role of chemotherapy) and the type of surgery does not usually change the recommendation. Tamoxifen is currently considered standard adjuvant hormonal therapy for premenopausal women in this country.  Studies are ongoing to determine whether the addition of ovarian ablation to tamoxifen or the combination of ovarian ablation plus an aromatase inhibitor will improve outcome compared with tamoxifen alone.

We cannot give specific recommendations for your situation, but the potential benefits of each treatment must be weighed against the potential risks.  A second opinion is always an option.