(Seek Help) Long Term Luminal A BC transformed into TNBC (Surgery done and under chemo)

uvoooooo

Hi everyone who sees this post. I am posting this for my mom's circumstance. She has been diagnosed with breast cancer since 2007, which was luminal A category. She had reoccurance in 2016 and has been living as a metastasis patient since then with hormone therapy. Recently she has been newly diagnosed with a TNBC cancer in her left breast and she had undergo surgery to remove the left breast. I want to post her history and medical diagnosis here to seek instruction or help from the community. As her only family member and who just started working, I feel helpless. I would appreciate any advice from professionals and experienced patients. Also, I would like to help answer questions from whoever is finding my mom's treatment experience helpful.

📍I am especially concerned about what is our best practice to prevent her reoccurance and help her? Recently I can't help crying secretly in office seat. I want to try everything I can do to help her. I want her to take BRCA, HRD, PD-L1 tests. She argues that these tests are mainly for targeted therapy strategies and after she undergo all the chemotherapy things may already changed. Do you think we should take BRCA, HRD, PD-L1 tests of the sample? A big bow to whoever is willing to share something with me under the post. 🙇‍♀️

The comprehensive review from 2007 to 2025 here:

Medical History from 2007

• 18 years ago: The patient underwent "Left breast-conserving surgery + axillary lymph node dissection (ALND)" due to left breast cancer. Postoperative pathology indicated Invasive Ductal Carcinoma (IDC), no axillary lymph node metastasis, Luminal A subtype. Postoperative treatment included 6 cycles of CEF chemotherapy, radiotherapy to the left breast, followed by Tamoxifen for 5 years.
• 2016: A metastatic lesion was identified in the right pubis. The patient underwent "Resection of the superior pubic ramus" at Shanghai Ninth People's Hospital. Pathology confirmed Metastatic Invasive Ductal Carcinoma. Immunohistochemistry (IHC): ER (++), PR (++), HER2 (-), Ki-67 (5%+), Luminal A subtype. Tamoxifen treatment was administered.
• 2018: Disease progression occurred. Treatment was switched to Goserelin Acetate (Sustained-release Implant) in combination with Exemestane.
• September 2023: Disease progression occurred. Treatment was updated to subcutaneous Goserelin Acetate (Sustained-release Implant) combined with Fulvestrant and Dalpiciclib.
• September 2025: After 2 years of Dalpiciclib, drug resistance developed. Treatment with Abemaciclib was initiated. Zoledronic acid was administered for bone protection during this period.

Recent Surgery and Pathology (December 2025):

• December 2, 2025: The patient underwent Left simple mastectomy due to a left breast mass.
• Postoperative Pathology: Invasive Ductal Carcinoma (IDC), Grade II of the left breast. Tumor size: $1.6 * 1.5 * 1 cm. No lymphovascular invasion (LVI) identified. Nipple and skin were not involved.
• Resection Margin/Cavity Assessment: No cancerous involvement found in the nipple, skin, surgical cavity, or base of the left breast.
• Immunohistochemistry (IHC) (Report No. I25-05669): ER (-), PR (-), Ki-67 (30%+), HER2 Negative (-), p120 (Membranous +), E-Cad (+), CD34 (-), D2-40 (-).
• Staging & Molecular Subtype: pT1cN0Mx, classified as TNBC (Triple-Negative Breast Cancer).
• She's now taking AC chemotherapy and already finished the first chemo. Her doctor holds that after chemotherapy (we haven't decided how many rounds), the next step would be targeted therapy.

moderators

Hi @uvoooooo, and welcome to our Community. We're so very sorry for the reasons that bring you here, but we're really glad you've found us. You're sure to find our amazing forums a wonderful source of advice, information, encouragement, and support — we're all here for you and your mom!

Typically, the metastatic disease would be the priority to treat and get under control, but it's important to determine if the new breast tumor is in fact a new primary tumor with different characteristics and not a spread of the original metastasis.

Has your mom asked about a new biopsy of the metastatic cancer in her bones (if possible) in order to rule out that the hormone receptor-positive disease has not mutated to hormone receptor-negative disease? (See more here.)

And, if that is the case, can the doctors confirm that the tumor in her breast is a second primary (new, separate) tumor and not metastatic spread to the breast from the potential receptor-switched primary?

Knowing as much as you can about the tumor(s) your mom is dealing with will help designate the best treatment plan for both diagnoses — whether a new primary, metastatic spread, or resistance to current treatments. So, asking about genetic testing, genomic testing, and/or liquid biopsies may benefit your mom and help inform a treatment plan going forward.

Typically, we also always recommend getting a second opinion, including asking for a tumor board where many doctors weigh in on the situation, so that you can have more than one suggestion for treatment.

We hope this is helpful and that you find answers and a solid treatment plan soon.

Please keep us all posted on how your mom is doing and what is decided.

Sending hugs!

—The Mods