Chemo usually needed?

Hi Debrose:

Not sure what size tumor you have, because there are no units.

"T1mi" ("Microinvasive"): Tumor ≤ 1 mm in greatest dimension

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

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

People with smaller HER2-positive tumors can be found here:

https://community.breastcancer.org/forum/80/topics...

Under current consensus guidelines from the National Comprehensive Cancer Center (NCCN) for breast cancer (Professional version 1.2016), for hormone-receptor positive, HER2-positive disease IDC, treatment options vary by size and lymph node status.

When adjuvant chemotherapy is used, HER2-positive disease is usually treated with a combination of chemotherapy plus targeted therapy. Targeted therapy in such case means HER2-targeted therapeutic agents, such as "trastuzumab" (tradename HERCEPTIN).

Speaking in general, as of this date (Nov 2015), under current guidelines from the NCCN, for node-negative (N0), hormone-receptor positive, HER2-positive IDC:

Tumor greater than 1 centimeter (Tumor >1 cm):

Adjuvant endocrine therapy + adjuvant chemotherapy with trastuzumab (category 1)

Tumor 0.6–1.0 cm:

Adjuvant endocrine therapy ± adjuvant chemotherapy with trastuzumab

The plus or minus symbol "±" for T1b size tumors reflects that chemotherapy plus trastuzumab may or may not be selected. Thus, patients will work with their doctors to decide what to do in their particular case, which may within the current Professional guidelines applicable to the subgroup in question either include or not include adjuvant chemotherapy with trastuzumab.

If your friend's tumor was exactly 1 centimeter (at the upper edge of this group), her decision is within the guidelines.

Tumor ≤0.5 cm or "Microinvasive"

Consider adjuvant endocrine therapy ± adjuvant chemotherapy with trastuzumab (category 2B)

With these smaller tumors, the word "consider" is included regarding endocrine therapy (e.g., tamoxifen).

The ± symbol reflects that chemo with trastuzumab is optional and is not always recommended, because the risk/benefit analysis and personal risk tolerance may reasonably weigh against adjuvant chemotherapy with trastuzumab.

The "category 2B" designation applies to "adjuvant chemotherapy with trastuzumab" (category 2B is a lower level of consensus than category 1).

The option of adjuvant chemotherapy with trastuzumab for this last group (Tumor ≤0.5 cm or Microinvasive) was recently added to the guidelines in 2015 based on the results of Tolaney et al. ("Dana-Farber study") (Tolaney SM et al., Adjuvant paclitaxel and trastuzumab for node-negative, HER2-positive breast cancer, N Engl J Med 2015;372:134-141):

http://www.nejm.org/doi/full/10.1056/NEJMoa1406281...

The discussion in this paper acknowledges that the risks of the regimen used may be seen to outweigh the benefits, particularly in smaller tumors.

With small tumors less than or equal to 0.5 cm (5 mm), the risk/benefit analysis of adjuvant chemotherapy plus trastuzumab may lead some patients to reasonably decline such treatment, especially those with "microinvasive" disease. So, patients will need to work with their doctors to reach a decision in light of their personal risk tolerance.

I am just a layperson, so please be sure to confirm the above with your MO. You can ask what current consensus treatment guidelines provide for your size tumor, and request more discussion of your personal risk benefit analysis. If you would like more discussion, input, perspective, or confirmation of the advice received, please consider obtaining a second opinion regarding your post-surgical treatments.

BarredOwl

Hi:

FYI, OncotypeDX for invasive disease is not used in the HER2-positive setting. Eligibility information here indicates "HER2-negative" only:

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

BarredOwl

Hi Debrose:

Just closing the loop per the other thread:

It is an excellent idea to obtain a copy of your report, clarify what was found in the node, and to seek a second opinion.

The guidelines differ depending on the degree of node involvement. Please note that the all the information I provided above is specific for "node-negative" disease. Remember to ask what the guidelines provide for a tumor your size with your node status.

With a second opinion, you can also seek a review of the pathology (slides sent overnight to other institution). This would permit a review of the determination of HER2 status and node status, the accuracy of which is central to your decision, especially with a 0.05 cm (0.5 millimeters) microinvasion.

BarredOwl