Posterior Axillary Boost - to do or not to do . . .

Started by Gfunk6
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Gfunk6

Gfunk6

And to think . . . I hesitated
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Lady in her mid-40s is pre-menopausal. cT1N1 IDC (ER/PR negative, HER2 positive). She got a lumpectomy and full ALND.

4/16 LN positive, no ECE, largest deposit 1.5 cm
Primary tumor widely excised
pT1N2a

She finished six cycles of TCH and now sees me.

I was planning on treating her whole breast, boosting resection cavity and treating SCV. I didn't see much benefit to treating her axilla since she has (a) had a good dissection, (b) she has far less than 50% of LN positive, (c) no ECE, and (d) no LN tumor deposit > 2 cm.

I base this on a Canadian retrospective study. However, I realize this is a highly controversial topic and other data (Beaumont comes to mind) exists.

Thoughts?
 
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I would not go supplemental XRT to the dissected axilla. Here is a paper from MD Anderson that shows the rate of failure in dissected axilla is low

http://www.ncbi.nlm.nih.gov/pubmed/16169678

Even gross ECE, large nodal size did not predict for axillary failure, but did predict for failure in the infraclav or supraclav region.

My experience has been a lot more lymphedema in patients that get a PAB and the yield seems very low on this patient.

I usually now only give a PAB if the patient has not had an adequate lymph node dissection.
 
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Gfunk6 said:
Lady in her mid-40s is pre-menopausal. cT1N1 IDC (ER/PR negative, HER2 positive). She got a lumpectomy and full ALND.

4/16 LN positive, no ECE, largest deposit 1.5 cm
Primary tumor widely excised
pT1N2a

She finished six cycles of TCH and now sees me.

I was planning on treating her whole breast, boosting resection cavity and treating SCV. I didn't see much benefit to treating her axilla since she has (a) had a good dissection, (b) she has far less than 50% of LN positive, (c) no ECE, and (d) no LN tumor deposit > 2 cm.

I base this on a Canadian retrospective study. However, I realize this is a highly controversial topic and other data (Beaumont comes to mind)

Thoughts?
Click to expand...

There are two issues here: 1. Is additional axillary tx needed? & 2. Is a traditional PAB field required to adequately cover the axilla?

The first is the tougher question. MA-20 (abstract from ASCO 2011) would suggest that axillary tx is beneficial (~33% DFS benefit and trend toward OS benefit). POF data, however, would suggest that risk of axillary recurrence, and in particular isolated axillary recurrence, is low for N1-2 dz. It's similar to the controversy re IMN treatment. Proponents of comprehensive nodal tx will argue that residual microscopic dz in axilla/IMN/SCV is the nidus for subsequent distant progression, even if measurable failure in those nodal regions never occurs. The argument to routinely treat the axilla in patients like this will become much stronger once MA-20 gets published in a peer reviewed journal, but until then I don't think that comprehensive nodal RT is necessarily SOC in all patients with positive axillary nodes. At present, I always treat dissected axilla in pts with N3 dz and high nodal ratio (>50%), and treat on case by case basis in pts with N2 dz. I agree, would probably not treat the dissected axilla in this pt.

For the second question, I contour volumes for all regional nodal treatment using RTOG atlas. I find that the traditional PAB is rarely needed to adequately cover the contoured axilla.
 
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About MA.20... If treating the regional nodes provides such a benefit, shouldn't the threshold to treat the chest wall/SCV/level III go down? If that data is to believed, then one has to believe that any one with nodal positivity will benefit from PMRT in this modern era. With optimal systemic therapy and 3D planning, the therapeutic window is much less narrow. I've changed my practice in that anyone who is healthy and is node positive is a candidate for treatment. For triple negative patients, there is randomized data indicating a benefit of PMRT in T1-T2N0 patients treated with mastectomy and chemotherapy.
 
I would not treat the axilla, until final MA20 data becomes available and put into effect in clinical practice.

If you are going to treat the axilla, you should also treat the IMC.

:laugh:
 
medgator said:
Yup.... a big drawback of MA20 IMO.... hardly anyone wants to treat the IMCs
Click to expand...

IMN irradiation was given in the British Columbia, Danish 82b, and Danish 82c trials that provide the textbook justifications for post-mastectomy radiation therapy. MA-20 is a Canadian trial, so it's no surprise that MA-20 would be consistent in that way.

The question remains: irradiation of which nodal groups benefit distant progression free and overall survival? As we know, many retrospective analyses over the years have attempted to define this. Prospectively, there was the negative French IMN irradiation trial (which was probably underpowered...). There was an early Italian trial of surgical dissection of IMNs that was negative, though gave more information about when IMNs are involved. Based on all of this information, at our institution we do irradiate IMNs for most N2 disease, and even N1 of the UIQ as there is a higher risk of IMN drainage there. In N1 disease, we also look at any CT imaging available to assess the IMNs and treat nodes with a cutoff of about 7mm. But, that is an uncommon perspective in the USA. Still, I imagine in Canada IMN irradiation is much more common (any Canadians around?).

I suspect in the end that irradiation of each nodal group gives some benefit in select groups of patients. But, without technology advances to find micrometastatic disease, it remains an open question as to irradiation of which nodal groups will benefit which patients. I think if we want to be most consistent, we probably should be irradiating all nodal groups in the post-mastectomy setting if MA-20 is published with an overall survival benefit. But I know that will remain controversial given the higher lung and heart doses required.
 
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wagy27 said:
Have to say, that i see the same data you are using, and feel that with what we have to date, there is a limited rol for IM treatment at this time. The data supporting IM RT just isnt there, beyond simply stating that it was used in the PMRT trials and an Israeli trial I believe. To me its the same poor arguement used in prostate to treat pelvis in the face of a negative randomized trial by saying they were used in the old RTOG trials.
Click to expand...


I cannot agree with you.

The problem is that the question of whether or not irradiation of the internal mammary chain is valuable are not was asked using the WRONG trials.

Look at this fine waste of resources:

http://www.redjournal.org/article/S0360-3016(09)01071-2/fulltext

Ten-year Results of a Randomized Trial of Internal Mammary Chain Irradiation after Mastectomy

Purpose/Objective(s)
To evaluate the impact of internal mammary chain irradiation (IMC-RT) on long-term survival in breast cancer patients treated with mastectomy.

Materials/Methods
Multicentric randomized Phase III trial comparing chest wall, axillary, and supra-clavicular irradiation with or without IMC-RT in newly diagnosed Stage I and II breast cancers. Inclusion criteria: patients under 76-years-old with positive axillary nodes or internal/central tumor location whatever pN. Stratification was done by center, nodal status, and tumor location (internal/central vs. external). The IMC-RT consisted in a combination of photons (12.5 Gy in 5 fractions) and electrons (32.5 Gy in 13 fractions) over 5 weeks. The target field included the first five intercostal spaces. Adjuvant chemotherapy or hormonal treatment was at the discretion of the physician. We planned to include 1,200 patients that allowed us to detect 10% difference in 10-year overall survival.

Results
A total of 1,334 patients have been randomized. Mean age was 56.5-years-old, 1,003 (75%) patients had positive lymph nodes. With a median follow-up of 10 years, we observed 535 deaths. Ten-year survival was 62.57% in case of IMC-RT and 59.55% without IMC-RT (p = 0.8762 by log–rank test). No difference was obtained in the different subgroups: positive or negative axillary nodes, external vs. central/internal tumors, or according to the different histologic subtypes, adjuvant chemotherapy, or hormonotherapy. Causes of death are known in 422 patients: most of these deaths were due to breast cancer (371); no increase in cardiac toxicity was observed in the IMC-RT group.

Conclusions
Using IMC-RT did not improve overall survival in this large randomized study.


Now, tell me... Which IDIOT told the statistician, that they think irradiation of the IMC would provide a 10-YEAR-OVERALL-SURVIVAL-BENEFIT?
😕😕😕

That's like saying IMC-irradiation is a good as chemo, oh wait, it's even better than chemo!
It's like Tamoxifen!

:laugh::laugh::laugh:


We need trials, which are designed in the correct way to evaluate the effect of extensive nodal treatment. The MA20-trial was a very good trial and when its results mature and if things turn out the way the look like right now, extensive nodal irradiation is going to become standard of care for every female with a node-positive breast cancer probably.
 
Palex80 said:
Now, tell me... Which IDIOT told the statistician, that they think irradiation of the IMC would provide a 10-YEAR-OVERALL-SURVIVAL-BENEFIT?
😕😕😕

That's like saying IMC-irradiation is a good as chemo, oh wait, it's even better than chemo!
It's like Tamoxifen!

:laugh::laugh::laugh:
Click to expand...

The problem is you would need tens of thousands of women to power a trial to detect a minute, statistically significant benefit to IMN radiation.

Regarding the MA-20, I think it has a lot of problems. Once it comes out we can go through it with a fine tooth comb but honestly, I don't think it will be practice changing in the US.
 
Palex80 said:
The MA20-trial was a very good trial and when its results mature and if things turn out the way the look like right now, extensive nodal irradiation is going to become standard of care for every female with a node-positive breast cancer probably.
Click to expand...

I'll be curious to find out how well that trial is adopted by the RO community in the US vs Canada and Europe in terms of treating the IMNs
 
wagy27 said:
I understand what you are saying in that the trial was not well designed but I really don't see much data supporting th use of IM treatment. What studies are there to really justify the treatment? Just because they were used by MA20 and the PMRT, does not in my mind provide justification for the addition to regional treatment.
Click to expand...

Define "regional" treatment...

We know that treating the chest wall is the most important aspect of post BCS or mastectomy irradiation. But what do we know about the lymphatics?
- Do we know if treating the SCV is more important than treating the axilla?
- Do we know if we have to treat the axilla in pN2 patients, who have underwent complete surgical axillary clearance? And if yes, are high tangents all we need or should we actually put a posterior axillary field?

There are so many questions open and so few answers out there.
The best thing would be to have an 6-arm-randomized trial for pN+ patients:
1. breast / chest wall only
2. breast / chest wall + axilla
3. breast / chest wall + SCV
4. breast / chest wall + IMC
5. breast / chest wall + axilla + SCV
6. breast / chest wall + axilla + SCV + IMC

1.000.000 patients needed to detect a 5% difference in recurrence free survival at 10 years?
Maybe we should ask the Chinese to carry out a study like that, they probably treat that many patients in a year or so...
:laugh::laugh::laugh:


MA20 was a fine trial without any problems in my opinion. Let us all wait for the final data and then decide whether to treat like that or not.
In 20 years we should have enough proton centers running to treat pN+ patients, without having to be afraid of excessive heart/lung toxicity.
 
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Details and subtleties of MA.20 need to be published and reviewed before RNI can be adopted as SOC for all node positive patients. Certainly not the kind of data that can be adopted based on abstract presentation alone. Agree with Palex though, the results will likely be practice changing when published... Particularly if OS benefit emerges...
 
From reading some of the above posts, I get the impression that we think MA20 will answer the initial post, ie the role of PAB. My reading of MA20 is that most patients did not receive PAB. Only recommended if >3 LN+ (which was almost nobody) or <10LN dissected. Patients most likely received treatment to IMNs and SC/ax apex only without axillary treatment. Don't think MA20 will answer the PAB question.

BTW, Nice link to the Chinese RCT of PMRT for triple negative, hadn't seen that.
 
"From reading some of the above posts, I get the impression that we think MA20 will answer the initial post, ie the role of PAB. My reading of MA20 is that most patients did not receive PAB."

Yes, but GFunk's pt had 4 positive nodes and would have been treated with PAB on MA.20

"Only recommended if >3 LN+ (which was almost nobody) or <10LN dissected."

You are correct, majority of pts in MA.20 had pN1 disease. Only ~15% of pts had >3 nodes. That said, it is a very large trial (by radiotherapy standards), and that 15% is a relevant number that will likely help answer the initial post.

"Patients most likely received treatment to IMNs and SC/ax apex only without axillary treatment. Don't think MA20 will answer the PAB question."

That's why publication is needed, because we don't get adequate detail from the abstract
 
When you guys say PAB, do you mean "boost", as in a dose higher than microscopic (like a boost to the lump cavity) or do you a mean utilizing a supplemental posterior field to bring the entire level I and II axilla to a microscopic dose or 45-50 Gy? It seems to me people don't really mean "boost", that they just mean treating the low axilla to a microscopic dose.

If I want to cover level I and II, I contour out level I and II, and make sure it gets 45-50 Gy, be it through higher tangents or whatever 3D arrangement that covers it, if doing a chest wall/SCV case.

Starting to do high tangents more, b/c of Z11. Very, very rarely treating full axilla. I think people use that old dataset from Fowble to justify treating axilla (the one that indicated high nodal positivity and inadequate dissection were risk factors for axillary recurrence). The had increased risk of recurrence with risk factors, but it was still really small numbers, and they didn't have any RT at all (which does treat some of the low axilla). And it was old school chemo, mostly CMF and the like.

MDACC's data showed in modern chemo era, low risk of failure in axilla regardless of what risk factors you looked at (3%) and that the risk factors people think of (inadequate dissection, ECE, high nodal positivity) indicate increased risk of CW/SCV/level III failure. Quebec data indicates 9% failure in axilla at 10 years vs 3% if 50% nodal positivity, which doesn't really reach the 15-20% threshold we use to recommend RT. But, the main thing is, if a lady has 16/18 positive nodes in her axilla, regardless of her ask of axillary or other locoregional recurrence, the distant recurrence has risen to the point of diminishing returns of more locoregional treatment. The combined treatment is pretty toxic, and I've seen pretty nasty lymphedema.

-S
 
SimulD said:
When you guys say PAB, do you mean "boost", as in a dose higher than microscopic (like a boost to the lump cavity) or do you a mean utilizing a supplemental posterior field to bring the entire level I and II axilla to a microscopic dose or 45-50 Gy? It seems to me people don't really mean "boost", that they just mean treating the low axilla to a microscopic dose.
Click to expand...

Good point of clarification. I was talking about using doses of 45-50 Gy, not truly a "boost." There are rare situations where going to 60 Gy might be appropriate such as in a clinically positive axilla when a patient refuses lymph node dissection.
 
I know that I am probably in the minority here, but I think I would treat gfunks patient with a PAS (supplement) to have a dose of 46 gy.

as for the French trial for IM RT, they excluded Stage III patients, who are the ones who would probably benefit the most from IM RT...

Have any of you ever presented a patient on chart rounds.com? You can present a patient and get Bruce hafftys opinion on the case live. You'll also get CME credits and it's free.
 
BraggPeak said:
Have any of you ever presented a patient on chart rounds.com? You can present a patient and get Bruce hafftys opinion on the case live. You'll also get CME credits and it's free.
Click to expand...

I'll give props to chartrounds.com. I haven't presented a patient on there, but I've listened in to several discussions, and it's quite good. The faculty have been great with questions and have been honest and open discussing how they'd treat the cases.

You can learn a lot from these.
 
Gfunk6 said:
Lady in her mid-40s is pre-menopausal. cT1N1 IDC (ER/PR negative, HER2 positive). She got a lumpectomy and full ALND.

4/16 LN positive, no ECE, largest deposit 1.5 cm
Primary tumor widely excised
pT1N2a

She finished six cycles of TCH and now sees me.

I was planning on treating her whole breast, boosting resection cavity and treating SCV. I didn't see much benefit to treating her axilla since she has (a) had a good dissection, (b) she has far less than 50% of LN positive, (c) no ECE, and (d) no LN tumor deposit > 2 cm.

I base this on a Canadian retrospective study. However, I realize this is a highly controversial topic and other data (Beaumont comes to mind) exists.

Thoughts?
Click to expand...

Haven't been on here in a while eh =) ... but I think in this scenario it comes down to the physian. Tim Whelan is one of our rad oncs here and among our breast group, there exists variation in whether or not this patient would get rads to the axilla. I've worked with staff personally who feel that data we have from our center suggests that treating the axilla increases the risk of lymphedema only minimally so they go ahead whereas others quote higher numbers in the literature and wouldn't treat the axilla. Personally, I would include the axilla in this patient.

As for data for MA.20, it sort of has changed practice at our center in the sense that when treating breast, we do try to include IMN whenever possible if cardiac constraints are met. So far this hasn't been a problem, and many of our breast patients now get their IMN treated.
 
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