Incidence of reoccurance and rationale for Sentinal Node Biopsy

[mtri]

I am a 50 year old with recent diagnosis of:
Infiltrating Ductal (well-differentiated tubular) carcinoma
Tumor size:  .9 x .8 x .7 cm; Elston Score:  4/9; Grade:  1
Lymphatic/vascular invasion: absent;  dcis: absent
Location of microcacifications:  benign breaset tissue
Margin Status:  Invasive carcinoma negative; closest distance to margin:  3 mm deep; still pending ER status and proliferative index.
    My questions:  Since my surgeon has already removed a section measuring 4.2 x 3.8 1.2 cm. and feels she does not need to remove any more, she is recommending a Sentinal node biopsy.  I will be meeting with her tomorrow for a treatment plan and referrals to oncologist and radiation oncologist.  How effective is a Sentinal Node Biopsy when the tumor has been already been removed.  I am not considering a axillary node dissection at this time.  Also what is the incidence of skip metastisis in this type of cancer?  Isn't a 3mm clear margin good enough not to have to do a biopsy at all?  Or at best, attempt a SNB if no nodes are visable stop at that point.  I am weary of overkill in an early breast cancer diagnosis such as this.  Would the results of the ER/proliferative index have any added affect to this decision?  Thanks,  M.T.

[CCF-RN,MSN-JS]

Dear M.T., The main purpose for checking the lymph nodes is to decide about adjuvant treatment (Adjuvant treatment is treatment given after surgery to try to prevent or minimize the growth of microscopic deposits of tumor cells that might grow into a recurrent tumor).  The standard of care is to check the lymph nodes by either axillary dissection or sentinel lymph node dissection.  Particularly in an early stage cancer (stage I or II, with a tumor less than 2 centimeters), where there are no palpable (felt on physical exam) nodes in the armpit, a sentinel node biopsy may be done instead of a full axillary lymph node dissection.  An argument against sentinel lymph node biopsy is that is not foolproof; it could still provide a false negative.  This happens in about 5% of cases; the sentinel node shows no cancer, and then cancer is found in other nodes at full dissection (although regular dissection can also miss some positive nodes.)  Studies are now following women long-range to see if those who have had only sentinel biopsy where no cancer was found developed axillary recurrences later on in life.  Currently the standard of care is for women who have a sentinel node that is found to contain cancer to go on to have a full dissection.

The information regarding ER status, and proliferative index, would not change the decision to check the lymph nodes.

[surgeon]

Knowing whether the tumor has spread to lymph nodes is important in planning further treatment. When there is invasive cancer, the possibility of such spread exists, independent of surgical margins, ER status, etc. So at the current time, it is considered important to check for lymph node involvement whenever invasive cancer is found. Sentinal node biopsy is the least "invasive" way to check, with the lowest chance of side effects such as arm swelling or numb areas of the skin. Your question regarding skip areas is a good one: the accuracy of sentinal node biopsy, in terms of finding lymph node spread if it is there, is in the 95% range, in experinced hands. Which means it could miss around 1 in 20 cases. It's still under investigation, whether such a miss has long term significance. Your tumor is small, and not aggressive-appearing under the microscope from what you said; so the chance of lymph node spread is less that with larger more aggressive tumors. The only reason to skip the procedure is if your oncologist would recommend chemotherapy no matter what is found, and in the same recipe of drugs. Most would base that decision on lymphnode status.