Worried to skip Radiation Therapy following Mastectomy and pCR - DCIS w/ lymph node

First time post. Thank you for any input. I apologize if I’m not describing this correctly and am too long winded in my description.
I am 60 years old and was diagnosed initially with DCIS (Grade 3, ER, PR negative) Stage IIA, but have some invasive component as I had one positive lymph node following biopsy. Lymph node biopsy showed HER2+, ER 15% and PR 1%.
I underwent 6 treatments of THP followed by mastectomy. Surgeon removed 3 sentinel lymph nodes. My pathology report showed a clear response - no residual cancer anywhere.
Radiologist is recommending 5 weeks Radiation to chest and all regional lymph nodes. He and my breast surgeon don’t believe the B51 study would apply to me because they have listed my diagnosis as TisN1M0 - which is strange to me because it had to be some component of invasive cancer because of my lymph node involvement.
I saw two other radiation oncologists for a second and third opinion - one was adamant that I do not need radiation (basically saying to run if anyone tells me otherwise) and the other said he would offer me the opportunity to omit if I were his patient. They both felt that my continuation of HP would take care of any potential microscopic cancer cells left and because I will be on Letrozole.
Is there anyone in a similar situation who decided to skip radiation? I would appreciate any thoughts. Thank you so much.
Comments
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Hi @esposito, TisN1MO is DCIS with no tumor mass but with a positive lymph node so technically it is not called invasive since it hasn't spread into the surrounding breast tissue. That lymph node is probably why your RO is recommending radiation. Both second opinion ROs recommended skipping the radiation figuring that HP and letrozole will be enough to prevent recurrence. The 2:1 recommendation of no rads is a tiebreaker but it's up to you to do what you're most comfortable with.
Radiation lowers the rate of local recurrence by 22% over the first 10 years only. The survival rate for both those who choose it and skip it is the same after 10 years. HP and letrozole both reduce distant/local recurrence by 50% so they have more of an influence on your theoretical outcome. If reconstruction is in your future plans radiation often means that implants are not an option and flap surgery has to be done.
It's tough to decide but you need to go with what feels right for your situation. All the best for figuring out what to do.
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@maggie15 Thank you so much for your reply. I appreciate your explanation of TisN1 as for some reason I didn't get that explanation clearly from my surgeon! If I can bother you again - I am not sure I understand what you mean by HP and letrozole reducing local recurrence by 50%. How is that compared to the 22%? I am so sorry but I just am not understanding but would so appreciate you clarifying. thank you
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@esposito, 50% = 50/100 = 1/2. This is the theoretical amount HP and letrozole reduce the risk of your cancer coming back locally ( in breast / lymph nodes) or distantly (metastatic to bones or organs.) 22% ≈ 20/100 = 1/5. This is the theoretical amount radiation will reduce the chance of cancer coming back locally.
You can ask your doctor what his estimated risk of your cancer recurrence would be. Your situation is unusual so I would not hazzard a guess. For example, if your chance of recurrence is 10% (90% chance of no recurrence) HP and letrozole would cut the risk in half to 5% (.5 x .10 = .05) giving you a 95% chance of no recurrence. With the same scenario radiation would reduce the risk of local recurrence by 2% (.2 x .10 =0.02) giving you a 92% chance of no local recurrence but would have no effect on distant recurrence. Doing both would give you a slight improvement in local recurrence over just the HP/letrozole but possible side effects from radiation as well as limiting reconstruction options may not make that worthwhile. Chest/lymph node radiation can have more serious side effects like lymphedema, pneumonitis and heart complications which may be why your second opinion ROs were against it. You can apply the math to whatever estimate your doctor comes up with.
I had no idea of how complex breast cancer can be and how many different variations there are. It's a bit of a learning curve but it's good to understand your situation so that you can make informed decisions for yourself. Ask away if you have other questions. I'm forever grateful to the people here who answered my questions when I was a newbie.
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@maggie15 I truly can’t thank you enough for this thorough explanation! It really is so complex and obviously there are different nuances to every individual. You stated it so perfectly and what I’m trying to do - get as much knowledge as I can about my situation so when I make a decision I can feel confident and live my life without looking back or nervousness. Again - thank you so very much!
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@esposito, I agree with Maggie your RO should give you estimates on recurrence with and without radiation. For me, post-mastectomy radiation was predicted to cut risk from 14% to 7%. Your situation my be more difficult to estimate.
If I am reading the 2024 B51 report correctly, you are exactly the patient who does not need radiation to all the lymph nodes. Covering each of the three groups increases toxicity, particularly the internal mammary nodes, which account for only 9% of ALL nodal recurrences, and usually occur in patients with invasive tumors near the sternum and deep to the chest wall. This is not you. So even if you had a 10% chance of nodal recurrence, likelihood of it happening in the internal mammary nodes would be an absolute 1%.
Sometimes ROs use a one-size-fits-all approach. For what it’s worth, I had a large, node-negative tumor and my RO insisted on covering chest wall and all three nodal groups. When I later questioned him on it, he had no studies to back up his decision, but finally threw up his hands and said it was “because that’s how we always do it.” Two years later the department came out with guidelines saying they wouldn’t have given me radiation at all.
Which is a very roundabout way of saying I think you are doing the right thing by getting other opinions. Good luck with your decision!0 -
@ratherbesailing Thank you so much for your comments! They are extremely helpful. I did question my RO and he gave a similar response that as of now this is the standard protocol by their governing bodies and so that's what they recommend. I truly so appreciate your thoughts! I am going to sit with my husband today to make a final decision. I was hesitant to post and now am so happy I did! Thank you!!
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