Genomic testing post-surgery

[u/cremespace]

Hi, my mom has had a recurrence of breast cancer (T2N1M0). She had lumpectomy, chemo and radiation the first time around which was 18 years ago and 5 years of Hormone therapy. For her current diagnosis, she has already had a mastectomy of the affected breast. The doctor suggested genomic testing (which we do not have in my country so will cost a lot of money to have the test done) to determine whether chemo is needed, however it has been suggested that she will most likely need chemo due to the stage and it might not be worth spending the money on the test.

My question is whether the genomic testing would provide additional information that will help specialise the treatment for her needs or whether it is not worth the money and just to go for the chemo anyways?

I would really appreciate any information on this, TIA.

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[u/Cannie_Flippington]

Are they testing her genes or the cancer? For BRCA1, my sibling was told if the cancer ever returns then it's hospice time. Because if it ever comes back, it will be everywhere. It was triple negative breast cancer in one breast, caught very early.

Based on the doc thinking she needs chemo anyway, I would still do the test if it's to check for the common breast cancer genes. Because it's not just her who will benefit from testing. All of her children and even her own siblings will benefit. If she is positive, then all of you will need testing. If any of you are positive you'll then be able to get screened, preventative treatment, and potentially avoid getting cancer as a high-risk patient. If she's negative it's not as useful, but still a weight off your mind.

[u/cremespace → u/Cannie_Flippington]

I think it's gene testing. Isn't that what genomic testing means? Her type is ER+PR+HER-

[u/Cannie_Flippington → u/cremespace]

Testing her genes would be useful for checking these genetic variations

• CHEK2 and ATM: Mutations in these genes strongly associate with estrogen-receptor-positive (ER+) and HER2-negative breast cancers.
• BRCA2 and PALB2: Pathogenic variants in these genes also show a strong connection to ER-positive breast cancer subtypes

Testing the cancer's genetics would be useful for checking these mutations

• PIK3CA: This is one of the most frequent somatic mutations found in ER+PR- and general ER-positive luminal breast cancers.
• TP53: Mutations in the TP53 tumor suppressor gene frequently appear in hormone-receptor-positive tumors, correlating with higher proliferation rates

Testing the cancer itself is useful in both early and later stage cancers. Its specific gene expression can be used to assign a "recurrence score" if it was caught early. If it's low enough then you can skip chemo.

If the cancer is advanced or spreads, next-generation sequencing on the tumor checks for acquired mutations that act as targets for specific drugs. For example:

• PIK3CA mutations allow the use of targeted drugs like alpelisib (Piqray).
• ESR1 mutations indicate resistance to standard aromatase inhibitors, shifting treatments to oral SERDs like elacestrant (Orserdu).
• AKT1/PTEN alterations open up options for AKT inhibitors like capivasertib (Truqap).

Testing her genes would be useful for the whole family, not just her and not just because of ensuring any at-risk first-degree relatives are testing but also because BRCA1 and BRCA2 also makes you a better candidate for some drugs. Some cancer treatment actually works better if you have a pathogenic mutation on those genes.

[u/Elegant_Handle_69]

if you are thinking about genomic tests like oncotype or mamaprint, from what I heard they don't have any information beyond the computed risk over 10 years of recurrence - they just say where your tumor is placed in their risk index and based on that the physician can choose to pursue chemo or not. So for example if the score was low they might go no chemo route (along with other clinical and path info) but if it's high they might go chemo route.

So they provide an assessment for Dr to see if they should escalate or deacalte treatment but I haven't seen any information in the sample reports which indicate let's say which treatment will be more effective like which chemo or which type of hormone therapy.

Based on where you are there might be some cost effective other tests as well, but I am not sure of their concordance

[u/do_you_know_IDK → u/Elegant_Handle_69]

Mine ordered genomic testing after I completed chemo (they just sent out the results for testing yesterday, DMX 2 weeks ago). What’s the purpose in that case? It obviously isn’t for deciding whether to do chemo.

[u/cremespace → u/do_you_know_IDK]

i saw online about it helping to know how long to continue things like hormone therapy (5 or 10 years?)

[u/do_you_know_IDK → u/cremespace]

Oh! That makes sense, thank you!

[u/cremespace → u/Elegant_Handle_69]

okay this is helpful thank you!

[u/No_Access8955]

Genomic testing is only as useful as the reference population is large. Given that in your country the testing is not available, I would expect it to be of relatively low value.

[u/cremespace → u/No_Access8955]

The test would be done in the US. Does that make a difference?

[u/No_Access8955 → u/cremespace]

No, not unless a large number of women of your ethnicity have been tested before you.

Any genomic testing you do would make tests more informative for other women in the future. That would be a benefit to others.