Timing of Oncotype Test

Hi Girl:

Eligibility for the test is formally a little broader than what the guidelines provide about its usage.

This is a live link for eligibility:

http://breast-cancer.oncotypedx.com/en-US/Professi...

Here are definitions of tumor size under the TNM staging system, which are mentioned below:

T1mi: Tumor ≤ 1 mm in greatest dimension

T1a: Tumor > 1 mm but ≤ 5 mm in greatest dimension

T1b: Tumor > 5 mm but ≤ 10 mm in greatest dimension

If we assume node-negative, then the National Comprehensive Cancer Center (NCCN) guidelines for Breast Cancer (Professional Version 1.2016) do not include the Oncotype DX (21-gene test) invasive disease in node-negative ductal or lobular invasive breast cancer that is hormone receptor-positive, and HER2-negative when the Tumor ≤0.5 cm or Micro-invasive. This is consistent with the comments from your surgeon.

Regarding treatment of node-negative ductal or lobular invasive breast cancer that is hormone receptor-positive, and HER2-negative when the Tumor ≤0.5 cm or Micro-invasive, the NCCN guidelines say:

"Consider adjuvant endocrine therapy (category 2B)"

Thus, for these small tumors, under the guidelines chemotherapy is not included. The relevant discussion, which should still be correct says: "Small tumors (up to 0.5 cm in greatest diameter) that do not involve the lymph nodes are so favorable that adjuvant systemic therapy is of minimal incremental benefit and is not recommended as treatment of the invasive breast cancer."

In general, there may be cases in which it may be appropriate to depart from what guidelines provide, or where a patient may prefer to do so. For example, a patient with a 0.5 mm tumor (node-negative, hormone-receptor positive, HER2-positive) with unfavorable features might request the test and/or chemotherapy. I do not know enough about it to know what constellation of features might direct such a decision.

According to this 2013 paper on usage characteristics, it seems that at least in the past occasionally very small tumors were tested. (I don't know what drove that or if it was within guidelines or not at the time.)

http://jop.ascopubs.org/content/9/4/182.full

"RS use was greatest among patients with tumors on the borderline of chemotherapy choice, as dictated by guidelines. These include T1b, T1c, and T2 tumors. Use decreased in patients with very small (T1mic and T1a) and very large (T3) tumors, for whom decisions regarding chemotherapy were more likely to be based on size, given favorable pathology."

As you know from your other threads, lobular cancer has distinct features, even though the NCCN guidelines do not seem to treat it differently. So please take the opportunity to raise all of your questions and concerns with the MO, who has the most relevant expertise in this area. If the test is considered, you may also wish to ask about how well-represented lobular patients were in the studies of the test.

Glad the biopsy went smoothly. Will keep my fingers crossed.

BarredOwl

[By the way, you can access the NCCN Guidelines for Breast Cancer Professional Version at NCCN.org. Registration is free. The relevant chart ("BINV-6") is at page 18 of the .pdf document.]