Breast case - fractionation

[BobbyHeenan]

79 year old with a 4.1 cm ER/PR +, Ki 67%, Her 2 (-) IDC with neuroendocrine features.
Final path after lumpectomy pT2N0. 1/2 SLN"s had ITC's. One margin close at < 1mm but no tumor on ink.

I met with her pre op and we were thinking 26 Gy in 5 WBRT.

With that big of a tumor and close margin, would you boost on top of that or switch to 40 in 15 with boost?

Or just leave it at 26 Gy in 5.

She's in pretty good shape. Oncotype pending.

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[RADONC4285]

To me the question of 15 fx with a boost vs 26 with a boost depends on whether you'd consider doing high tangents to cover levels 1 and 2 given aggressive features and ITCs. I personally would do 15 fx with a boost and cover levels 1/2, especially if Oncotype is high or borderline high. if Oncotype is really low and you're not considering levels 1/2, then 26/5 with a boost is fine. A lot of pts on the UK trial did 26/5 then boost as you know.

 

[BobbyHeenan]

Shoot - I need to look closer at the boost on the 26/5 trial.
What did they use as boost dose?

 

[RADONC4285]

Shoot - I need to look closer at the boost on the 26/5 trial.
What did they use as boost dose?

 

[BobbyHeenan]

Thank you - that’s helpful!

I had similar thoughts on regular vs “high tangent” based on oncotype, etc.

 

[Palex80]

Excuse me, but what kind of tumor are we talking about here?
Is this an IDC "with neuroendocrine features" and a modest Ki67 of 10-20% or is this a poorly differentiated neuroendocrine carcinoma with a high Ki67 ?

 

[BobbyHeenan]

Aside:

If you're going to do a 16 Gy boost at 2 Gy/fraction, might as well not do 26 in 5 to the whole breast, no?

IMO the benefit (and what I've used 26/5 on thus far) is the 2-3 cm lobulars with negative margins in older patients and no planned boost.

 

[BobbyHeenan]

Excuse me, but what kind of tumor are we talking about here?
Is this an IDC "with neuroendocrine features" and a modest Ki67 of 10-20% or is this a poorly differentiated neuroendocrine carcinoma with a high Ki67 ?

Sorry - typo...Ki 67 was 30% I think (*correction, Ki 67 was 14% on biopsy. not repeated on lumpectomy specimen).

Agree, a weird tumor.



It's not a "poorly differentiated neuoreondocrine carcinoma." I asked about that.

Graded as a Grade II IDC but with neuroendocrine features. Synaptophysin +. Chromogrannin (-)

 

[Palex80]

Sorry - typo...Ki 67 was 30% I think (*correction, Ki 67 was 14% on biopsy. not repeated on lumpectomy specimen).

Agree, a weird tumor.



It's not a "poorly differentiated neuoreondocrine carcinoma." I asked about that.

Graded as a Grade II IDC but with neuroendocrine features. Synaptophysin +. Chromogrannin (-)

Ok, this sounds reasonable. I would say hypofractionation is ok in this situation.
And I woulnd't cover lymphatics. ITCs are <pN1 mi.

 

[FrostyHammer]

I'd proceed with 5 fractions... Can make arguments both ways but at the end of the day she's 80 and this is a very salvageable disease if it even ever comes to that.

 

[RADONC4285]

I'd proceed with 5 fractions... Can make arguments both ways but at the end of the day she's 80 and this is a very salvageable disease if it even ever comes to that.

reasonable, but if the tumor looks bad and sizable and she's in good health, then boost. if you're treating, then do your best to treat only once. same with the high tangents thing, it adds little to no morbidity to do it if she has a high oncotype. But I agree, 16 Gy boost is ridiculout. I would just do 10 Gy, that way she's done in 10 fractions

 

[evilbooyaa]

If you were thinking 26 in 5 pre-op, I don't see anything that makes you change that plan now. I, personally, would probably boost for large volume and close margin disease, and idk what to make of the neuroendocrine features. My personal preference is still 15-16fx + boost in this case, but wouldn't bat an eye if somebody else was doing 5fx + boost. IMO I also wouldn't bat an eye if somebody said they were going to conventionally fractionate this with the argument of 'erhmagerd, neuroendocrine features' so I'm probably more liberal on fractionation schemes than most would be.

Is this a surprise 4cm tumor?

 

[BobbyHeenan]

If you were thinking 26 in 5 pre-op, I don't see anything that makes you change that plan now. I, personally, would probably boost for large volume and close margin disease, and idk what to make of the neuroendocrine features. My personal preference is still 15-16fx + boost in this case, but wouldn't bat an eye if somebody else was doing 5fx + boost. IMO I also wouldn't bat an eye if somebody said they were going to conventionally fractionate this with the argument of 'erhmagerd, neuroendocrine features' so I'm probably more liberal on fractionation schemes than most would be.

Is this a surprise 4cm tumor?

I’d have to look back in EMR, but I think going in we thought 2-3 cm.

I might go 26/5 with a 10/5 boost.

 

[FrostyHammer]

if you're treating, then do your best to treat only once.

I agree with your approach too but this is not my style. That basically means not thinking and doing comprehensive nodes on most breast patients that walk thru the door (even many T1N0s meet MA.20/Eortc criteria). Is that really where we are going in the breast cancer realm? Yipes.

 

[RADONC4285]

I agree with your approach too but this is not my style. That basically means not thinking and doing comprehensive nodes on most breast patients that walk thru the door (even many T1N0s meet MA.20/Eortc criteria). Is that really where we are going in the breast cancer realm? Yipes.

But I'm not saying do comprehensive on T1N0 that meet MA20/EORTC. I'm saying do only level 1/2 for a pt with a 4+ cm tumor, high Ki67, ITCs, with neuroendocrine features and only if she has high Oncotype. I mean if MA39 is testing whether we can skip RNI in N1 pts with low oncotype, then makes sense to at least treat level 1/2 for N0 with ITCs with high oncotype. Having said that, i'm not saying my suggested approach should be standard or 100% backed by data at this point. More of a nuanced take based on the available data and limited morbidity of extending your tangents superiorly a bit to include 1/2

 

[FrostyHammer]

But I'm not saying do comprehensive on T1N0 that meet MA20/EORTC. I'm saying do only level 1/2 for a pt with a 4+ cm tumor, high Ki67, ITCs, with neuroendocrine features and only if she has high Oncotype. I mean if MA39 is testing whether we can skip RNI in N1 pts with low oncotype, then makes sense to at least treat level 1/2 for N0 with ITCs with high oncotype. Having said that, i'm not saying my suggested approach should be standard or 100% backed by data at this point. More of a nuanced take based on the available data and limited morbidity of extending your tangents superiorly a bit to include 1/2

Gotcha - I used that as an example against the philosophy of "doing one's best to treat only once" - I definitely believe in being more judicious and with heavy input from patients