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May 15, 2017 10:11AM
May 15, 2017 10:25AM
Recommendations for systemic therapy in this situation are made on a case-specific basis and entail significant exercise of clinical judgment by medical oncologists. In this type of situation, a second opinion from a medical oncologist at an independent institution can be a good way to probe the medical advice received and to seek additional professional input. The second opinion process also provides an opportunity for additional discussion and questions, and may be helpful to understanding individual risk/benefit profile. She can also seek additional input about particular regimens when recommended.
For information only, our local clinical consensus guidelines from the National Comprehensive Cancer Network (NCCN) (Version 2.2017) applicable to those with hormone-receptor negative, HER2-positive, ductal, lobular, metaplastic or mixed invasive breast cancer, that is node-negative (N0), with "Tumor ≤0.5 cm including microinvasive" provide for consideration of adjuvant chemotherapy with trastuzumab. (See e.g., Chart BINV-7)
Thus, in such case, chemotherapy plus trastuzumab is an option to be considered, and receiving or not receiving systemic treatment are formally within consensus guidelines.
This is a Category 2B statement:
"Category 2B: Based upon lower-level evidence, there is NCCN consensus that the intervention is appropriate."
In the appropriate case for such treatment, in the USA, trastuzumab (HERCEPTIN) would typically be included the regimen. In the appropriate case, chemotherapy with weekly paclitaxel and trastuzumab may be recommended (see Tolaney et al. (2015) below).
If access to trastuzumab (HERCEPTIN) is an issue in certain countries, and the systemic regimen does not include trastuzumab, I am not sure, but it seems possible that a stronger chemotherapy regimen might be considered in some cases. As a layperson, I have no idea, because the selection of particular regimen requires medical oncology expertise and clinical judgment. Again, a second opinion could be helpful in this regard.
As noted by ElaineTherese, with hormone receptor-negative disease, the patient does not have the option of endocrine (anti-hormonal) therapy.
Even with small tumors, negative nodes, and no lymphovascular invasion, there is some risk that some cells escaped the breast and moved to distant sites before surgery, laying the foundation for distant (metastatic) recurrence. The estimated size of this risk for the individual is one of the main considerations in recommendations for systemic drug treatments. See: https://community.breastcancer.org/forum/96/topics/854009?page=1#post_4941787
The decision requires a personalized case-specific risk/benefit analysis by a medical oncologist familiar with all of the relevant clinical (e.g., age, co-morbidities) and pathologic features of the individual patient's disease (histology, tumor size, etc). Age and multifocal disease are potentially relevant considerations. Differences in clinical and/or pathologic factors between patients may lead to differing medical advice. Differences in "risk tolerance" between patients may lead to different decisions under relatively similar circumstances.
Estimating distant recurrence risk may be more challenging in this situation, because smaller tumors are a less studied subset of HER2-positive disease, and the available studies are small. For example, with T1a or T1b tumors, there is quite a bit of variation between studies regarding the magnitude of the risks of recurrence (loco-regional and distant) that they face. In addition, for these smaller tumors, there is not as much clinical evidence available about the results of treatment (as compared with larger tumors).
As part of the decision-making process, patients should seek expert professional advice from medical oncologists regarding whether any clinico-pathologic features of their disease may present added risks, and request information about their estimated risk of distant recurrence (a) with systemic treatment; and (b) without systemic treatment. In order to weigh benefit versus risk, patients should inquire about the risks of any recommended drug regimen, such as serious side effects and their incidence, in light of their overall health, personal medical history and risk factors (e.g., co-morbidities).
Here is one recent study that influenced treatment guidelines in this area and led to revision of the NCCN guidelines in 2015 to include consideration of the option of chemotherapy plus trastuzumab for smaller tumors:
Tolaney et al. (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 this study, it appears that 9 patients (2.2 %) had microinvasive disease (Table 1). The discussion acknowledges that similarly situated patients may decide the question differently. If this study influences her thinking in any way, she should be sure to discuss it with her team to ensure accurate understanding and applicability to her particular situation, and to inquire about any more recent information.
I am a layperson, with no medical training, so please confirm all information above with a medical oncologist to ensure receipt of accurate, current, case-specific expert professional medical advice.
Under AJCC (7th Edition) staging criteria, size-wise only:
T1mi Tumor ≤ 1 mm in greatest dimension <=========== "microinvasive"
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
Stage IA IDC, 9/2013 BMX. Right: IDC (1.5 mm, grade 2) with DCIS (5+ cm), 0/4 nodes, pN0. Left: DCIS (5+ cm), 0/1 node, pN0(i+).