Extensive DCIS ER+ / PR- / HER2+

Hi LBBS_CJ:

Although you are in the right forum (for people with DCIS plus HER2-positive Microinvasion(s)), the title of your thread does not correspond very well to your question. You aren't asking about the DCIS component, but about the node-negative, ER+ PR- HER2+ microinvasion(s). You might get more replies from others with similar diagnoses with a revised thread title. If you wish to revise the title, you can send a Private Message to the Moderators and request that they revise the title of your thread to something like, "Node-negative ER+ PR- HER2+ microinvasion(s)" or even more generally, "Node-negative Hormone receptor-positive, HER2+ microinvasion(s)".

By the way, your treatment plan (Tamoxifen alone) appears to be within our current local clinical consensus guidelines for breast cancer from NCCN (Version 2.2017). Assuming the histology of the microinvasions was ductal, lobular, metaplastic or mixed, then for hormone receptor-positive (ER+ and/or PR+), HER2-positive, node-negative (pN0) disease, where the tumor is ≤ 0.5 cm (including microinvasive), the guidelines provide (emphasis added):

>> "Consider adjuvant endocrine therapy [x,y] ± adjuvant chemotherapy [z,aa] with trastuzumab [bb,cc] (category 2B)"

Thus, for the above situation, treatment plans either with or without (±) chemotherapy plus trastuzumab (HERCEPTIN) are within guidelines.

The results from the APT Trial (ClinicalTrials.gov number, NCT005424510), which influenced treatment guidelines for small, node-negative HER2-positive tumors, were published in late 2015:

>>Tolaney (2015), "Adjuvant Paclitaxel and Trastuzumab for Node-Negative, HER2-Positive Breast Cancer"

>>Main Page: http://www.nejm.org/doi/full/10.1056/NEJMoa1406281#t=articleDiscussion

>>PDF version: http://www.nejm.org/doi/pdf/10.1056/NEJMoa1406281

In the above 2015 publication, "The median follow-up time was 4.0 years. . . "

Note that it appears that only 9 patients (2.2 %) in the study had microinvasive disease (Table 1).

The discussion of the paper indicates that patients may decide this question differently, after a personalized risk/benefit analysis.

Just recently, seven-year follow-up data was recently released at ASCO 2017:

>>Tolaney (ASCO 2017), Abstract No. 511, "Seven-year (yr) follow-up of adjuvant paclitaxel (T) and trastuzumab (H) (APT trial) for node-negative, HER2-positive breast cancer (BC)"

>>http://abstracts.asco.org/199/AbstView_199_191222.html

This abstract reports after "a median follow-up of 6.5 yrs . . ."

Results from abstracts may be preliminary in nature. Those with pending treatment decisions should be certain to discuss any outside information with their medical oncologist to ensure accurate understanding and applicability to their particular situation.

BarredOwl

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"T1" = Tumor ≤ 20 mm in greatest dimension

The T1 size category is further subdivided as follows:

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

T1c Tumor > 10 mm but ≤ 20 mm in greatest dimension

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CORRECTION: The full-length paper of the APT Trial was published in the January 8, 2015 issue of the New England Journal of Medicine. Per my copy of Version 2.2015 of the NCCN guidelines for breast cancer (published in the April 1, 2015 of JNCCN ), the option of chemotherapy plus trastuzumab for very small HER2-positive tumors was first introduced into Version 1.2015 of the guidelines.

Moderators:

As an aside, the current title of this Forum is rather confusing: "Micro-invasive DCIS that is HER2 positive"

There are two types of disease present in this situation:

(1) some DCIS, which is "non-invasive"; and

(2) very small "invasive" tumor(s) each ≤ 1 mm in size, at least one of which is HER2-positive.

I recommend revising the title of this Forum to something like: "DCIS plus HER2-positive Microinvasion"

Additional Explanation:

As MinusTwo correctly noted, by definition, "DCIS" is confined to the inside of the ducts and is deemed "non-invasive" according to the determination of the pathologist.

Instead, what is "micro-invasive" is the associated "invasive" disease, which according to the determination of the pathologist has "invaded" the tissue surrounding the duct, and meets the size criterion for a microinvasion ("T1mi" = Tumor ≤ 1 mm in greatest dimension).

Also, it is unclear from the current Forum title what is HER2-positive (the DCIS or the microinvasion). In fact, this Forum is for those with HER2-positive microinvasion, because the HER2 status of invasive disease can impact advice regarding systemic drug treatment. (The HER2 status of the DCIS is not relevant to systemic treatment decisions under current clinical practice.)

Once any invasion is present (no matter how small), the pathologic diagnosis is "invasive" breast cancer (Stage IA or higher), and is no longer Stage 0 (pure DCIS).

When DCIS and microinvasion are both present, it is sometimes called "DCIS with microinvasion" or "DCIS-MI", but despite the name, DCIS-MI is an "invasive" breast cancer diagnosis. Patients with DCIS-MI should always consult with a Medical Oncologist.

BarredOwl

Thanks!

I had DCIS with a 1.2 mm invasive in 2013 that was Her2+. I had lumpectomy with radiation. I had 3 oncologists say it was to small to treat with Herceptin. I had a recurrence this year and had a mastectomy. It was 5cm DCIS that was suspicious for micromets but they didn't find it in the staining upon pathology. Had all the lymph nodes removed and nothing was there. I don't know if it was also Her2+ since they couldn't prove the Invasive componentwith pathology. Still need to meet with oncologist in August but I don't think they will give me Herceptin. It's very scary since I've had BC twice in less than 4 years.