2012 SAN ANTONIO BREAST CANCER SYMPOSIUM – WRAPPING UP SOME LOSE ENDS

There are many partially answered questions about the best ways to do things in breast oncology.  Several questions had great answers provided at this year’s San Antonio Breast Cancer Symposium (SABCS). Below is the newest information on how long to use adjuvant Herceptin (trastuzumab) and whether you can rely on a sentinel node biopsy after chemotherapy.

How long should a woman take trastuzumab (Heceptin)?

Trastuzumab, also known by the brand name, Hereptin, is the “poster child” for the future of targeted, individualized cancer treatment. 

About one-fifth of breast cancers have an overactive HER2 gene that makes the cancer more aggressive.  Trastuzumab literally reverses the effects of overactive HER2.  I’ve had patients with spread of cancer to their lungs and other places who’ve had what can only be described as a miraculous response to trastuzumab. 

More recently it has been shown that, if a woman’s breast cancer is tested and found to overexpress the HER2 gene, she will have better survival if she receives a year of trastuzumab before she has any evidence of spread of cancer.  This treatment before any evidence of metastasis is called “neoadjuvant treatment.”

The question has been whether one year of neoadjuvant trastuzumab is optimal.

Parallel tests of more or less traztizumab.

Two, back-to-back reports at the SABCS answered this question.  One study looked at whether 6 months of trastuzumab was not inferior to 1 year of treatment – a so-called “non-inferiority” test.  That’s’ a backwards way to ask if 6 months is as good as 12 months.  The researchers could not show that 6 months was as good as 12 months.

The other report looked at 2 years compared to 1 year of traztuzamab.  Many oncologists had assumed that, if one year worked, 2 years would be better.  It did not happen that way.  There was no improvement with the second year of trastuzumab. 

Answer:  One year of trastuzumab is just right.

Does sentinel lymph node biopsy work after chemotherapy?

Whether or not cancer has spread to nodes is a good guide in determining the best course of treatment to recommend.  For example, cancer in the nodes is a strong reason to consider chemotherapy, especially in younger women.

Using sentinel lymph node biopsy, also called SLNB, has helped doctors learn whether cancer is in nodes by evaluating only one or two or at most a few nodes.  This, in turn, has helped reduce the number of lymph nodes that are removed for the treatment of most women with early breast cancer.   The benefit of removing fewer nodes is a reduction in side effects of surgery such as lymphedema.  

Sometimes cancer is more advanced – possibly involving the nodes already – and it is desirable to give chemotherapy before surgery in order to shrink the cancer.  This can reduce the amount of tissue that must be removed from the breast, and thus improve cosmetic results.

The question has remained whether it is possible to rely on SLNB if the patient had chemotherapy before surgery.  It turns out there are three answers depending on what was done before chemotherapy began.  

Sentinel node when there has not been a node biopsy.

The easy situation is when a woman only had a biopsy of her breast to confirm that cancer was present, and then had chemotherapy without any node biopsy.  In this situation, SLNB is a reliable way to determine if there is cancer remaining in the nodes after the chemotherapy.  This has been known.  What has not been known is whether SLNB is reliable if a biopsy of a node was done to prove there was cancer in a node before chemotherapy was begun. 

Node surgery before chemotherapy can make sentinel node biopsy less reliable.

At SABCS, another pair of back-to-back presentations demonstrated that reliability of SLNB depends on the type of node biopsy that was done before chemotherapy.

If a SLNB was done as a surgical procedure – with isotope or blue dye node tracking, anesthesia, and a skin incision – then an attempt at a second SLNB after chemotherapy is not very reliable.  It finds the sentinel node only 61 percent of the time, and 52 percent of the time it was negative when another, different node had cancer – a so-called “false negative result.”  This is probably because the surgical SLNB scars the normal lymphatic channels that are needed for SLNB to work.

In contrast, if only a needle biopsy was done of a node before the chemotherapy, the results of SLNB are much more reliable.  There is a false negative result of only 13 percent.  If the surgeon uses two different ways to find the sentinel node, this false negative rate drops to 11 percent.  This is probably because using a needle to biopsy a node is much less disruptive of the lymphatic vessels.

In practice, this means that if the oncologist wants to know if a node is positive before administering chemotherapy, the pre-chemotherapy biopsy should be done with a needle rather than an open surgical biopsy.  That way, SLNB – with its benefits of less surgery and fewer side effects – can be used to assess the patient after the chemotherapy is complete. 

Answer:  Sentinel lymph node biopsy is reliable after chemotherapy if the nodes were not surgically biopsied before chemotherapy.   Remember, this information applies to the specific situation when chemotherapy is given before surgery to shrink a cancer and to improve the results of surgery.

More issues from SABCS in the next Perspectives on Women’s Health.

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