Is there a contraindication to using a medial electron field if you're using Canadian fractionation?

[XRT_doc]

Is there any contraindication to using a medial electron field if you're using Canadian fractionation for Breast Cancer?

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[Gfunk6]

Do you mean to treat internal mammary nodes?

 

[XRT_doc]

Do you mean to treat internal mammary nodes?

No, I mean when the tangents cause a high dose to the lungs (due to the patient's anatomy) an option is to use a medial electron field to allow more sparing of the lungs with the tangents. That's the field I'm referring to.

Thanks!

 

[medgator]

I would check the methods and materials sections of the whelan paper. They excluded a large chest diameter and I think their techniques were just photons only

 

[XRT_doc]

I would check the methods and materials sections of the whelan paper. They excluded a large chest diameter and I think their techniques were just photons only

But there have been several studies after that which didn't exclude patients with large chest diameters. I'm just not sure if they used electrons.

 

[Gfunk6]

Agree with medgator. On the rare occasions we cannot make Whelan hypofrac work due to dose heterogeneity (mainly), we abort to conventional fractionation. Alternatively treat to 45 Gy and boost resection cavity to 15 Gy.

 

[Burt Radnolds]

In my opinion, no, this does not preclude you from using a hypofractionated regimen. The Whelan paper was groundbreaking, but we have come far since then. I feel that many people misconstrue the dosimetric parameters of the Whelan paper, the ASTRO hypofractionated guidelines, and the START trial. They speak to dose in the central axis having a max of 105-107%. This is not necessarily representative of the overall global hotspot, and in my opinion was there as a conservative constraint based on employing a new dosing regimen, as well as due to the fact that these patients did not necessarily undergo 3D planning. For comparison, in the RTOG 1005 trial, using hypofractionation, they allow a 115% hotspot with no deviation, and a 120% hotspot as a minor deviation, while still employing a 12-14Gy boost additionally.

In your case, I think the decision would come down to several factors. If you are matching the electron field through the lumpectomy bed, it can be hard to get good coverage while keeping the hotspots down. If the cavity is far away from the match, you could leave it a little cold at the match to achieve a reasonable hotspot, or you could consider just skimping on coverage of the very medial breast tissue without doing anyone any harm. Obviously standard fractionation is not going to be wrong and you just need to do what you are comfortable with. I personally have a hard time justifying standard fractionation in almost anyone receiving whole breast radiation at this point. I think we will see a dramatic shift towards hypofractionation in the next ten years (or sooner) as the belt tightens on spending and bundling is put into effect.

 

[medgator]

. I personally have a hard time justifying standard fractionation in almost anyone receiving whole breast radiation at this point. I think we will see a dramatic shift towards hypofractionation in the next ten years (or sooner) as the belt tightens on spending and bundling is put into effect.

Not for people getting chemo, regional nodal XRT, or those with a >20 year life expectancy (IMO). I know ASTRO picked age 50 as a cutoff for recommending hypofx, but I still keep it closer to 60 (the age that ASTRO white paper felt was safe for PBI).

 

[Burt Radnolds]

So I specifically mentioned whole breast only, and did not delve into the discussion on regional nodal RT. However, START A/B allowed regional nodal radiation with no observed detriment and it is a much bigger trial than Whelan. I have treated patients with regional nodal RT with START fractionation, but typically only offer it to those with major barriers to care. The BED to the plexus is actually less with 40/15 than with conventional fractionation, even with an ultraconservative A/B of 1.5. However, again I never said it was standard for these folks.

Regarding younger patients... START actually showed better late cosmesis (and all cause mortality fwiw although very likely a fluke) with 40/15 compared to 50/25 at 10 years. I will concede that you could make an argument that cosmesis could wildly swing in the opposite direction after 10 years, but I personally find this unlikely. In regards to chemotherapy, 1000 patients in the START trials received adjuvant chemo, bigger than the entire Whelan trial itself, and again, even in the chemo receiving subgroup, cosmesis trended to favor the hypofractionated patients. An area that has not been investigated is neoadjuvant chemo, so I could see why someone would be gun shy in that situation.

I think this is a very interesting topic and would love to hear others opinions (outside of "my gut says hypofractionation is bad in these patients"). Once I thoroughly reviewed the 10 year results of the START trial (http://www.ncbi.nlm.nih.gov/pubmed/24055415), the results were so compelling that I had no choice but to consider 3 weeks regimens the standard of care for almost anyone receiving breast only/high tangent radiation, even young/adj chemo/wide separation patients. The ASTRO breast fractionation paper was accepted in revised form in April 2010, thats 5.5 years ago. A lot has changed, I expect to see an update soon.

 

[Gfunk6]

I hate to point out the obvious elephant in the room, but when you publish a paper saying that fewer fractions have equivalent efficacy/cosmesis than more fractions on one hand and, on the other hand, reimburse more for more fractions - that is cognitive dissonance.

In my view, this is the *major* reason that hypofractionation has not been widely adopted across the United States. When capitation finally comes, I predict that all the Rad Oncs (let's be honest, I include myself here) will have a eureka moment and start hypofractionating everyone.

However, since you ask, I perform Whelan hypofrac in all patients age 50 and older who did not undergo (neo)adjuvant chemo and do not require nodal radiation. In my practice this is still the slight majority of women receiving breast radiation.

FYI "my gut says hypofractionation is bad in these patients" is really a polite way of saying "my wallet says hypofractionation is bad for these patients."

 

[BobbyHeenan]

Like GFunk, the majority of my patients where I treat whole breast I will use canadian fractionation. However, I still use standard fractionation for chest wall or in patients where I treat the nodes/SCLV field the majority of the time.

I too reviewed the data like radoncmonkey says and was really not concerned about patients that got adjuvant chemo, so even in those patients where I'm only treating the breast I more often than not will use hypofractionated XRT.

For younger patients (age ~40) I still do standard fractionation but if there are barriers to care consider canadian fractionation. Especially if I feel a lumpectomy boost is indicated (younger, ER negative, close margins, etc), then I'm a little more wary about 16 fractions plus boost, where I would usually do 2.5 Gy X 4 boost. Since they're so young and data for boost cosmesis in hypofractionated treatment is a little less robust (though admittedly you have some patients on START and the old Lyon trial that had hypofrac plus boost), I favor standard fractionation (45 -50 @ 1.8 -2 Gy with 2 Gy X 5 boost).

I have found that my breast surgery referring docs appreciate the willingness to offer shorter treatments (or even observe low risk DCIS or older T1 ER positive patients). They seem to value/trust my opinion more knowing that I'm using techniques to help patients in spite of the financial hit. I think they're more willing to send me the borderline cases (neoadjuvant CR then mastectomy, > 70 ER positive, small DCIS, etc) to at least have the XRT discussion because they see that money is not the main driver in the XRT discussion.

 

[medgator]

Surprised you guys are doing hypoFx with chemo. I'll wait for the ASTRO update in the guidelines before I start applying UK data in practice. The majority of my patients are getting hypo, but I am not going to push the envelope too much without ASTRO/NCCN cover. And to Gfunk's point which is very valid, I will say "why take the potential toxicity/financial risk in a gray situation?" When ASTRO comes out and says start hypofractionating everyone, I'll do it.

 

[BobbyHeenan]

Surprised you guys are doing hypoFx with chemo. I'll wait for the ASTRO update in the guidelines before I start applying UK data in practice. The majority of my patients are getting hypo, but I am not going to push the envelope too much without ASTRO/NCCN cover, personally.

NCCN does say that for breast only treatment "short course is preferred," giving no qualifier about whether or not chemo is used. I understand wanting to wait on ASTRO though, I think that's perfectly reasonable.

For chest wall standard fractionation is the only NCCN option listed in the principles of radiation section.

 

[RadOncDoc21]

While we are on the topic of breast, is there anything wrong with just doing a boost dose to 56 Gy instead of the traditional 60-66 Gy? I'm treating a whole breast and axilla (no sentinel lymph node biopsy performed), stage IIa, no other significant pathologic features to 46 Gy to be followed by a 10 Gy boost, only because I was considering not boosting but felt obliged to since I was only going up to 46 Gy. The humeral head dose was also a littler higher than I thought it would be due to her anatomy.

 

[seper]

can you please point out (perhaps obvious) where recommendations not to use Canadian regimen for those getting chemo are coming from?

 

[medgator]

NCCN does say that for breast only treatment "short course is preferred," giving no qualifier about whether or not chemo is used. I understand wanting to wait on ASTRO though, I think that's perfectly reasonable.

For chest wall standard fractionation is the only NCCN option listed in the principles of radiation section.

Yeah although I know that people do hypofx in the UK/europe.

can you please point out (perhaps obvious) where recommendations not to use Canadian regimen for those getting chemo are coming from?

"Data was sufficient to support the use of HF-WBI for early stage breast cancer patients age 50 years or older, who had disease stage pT1-2 pN0, did not receive chemotherapy and were treated with a radiation dose homogeneity within ±7 percent in the central axis plane. Data was considered insufficient to make a judgment on the use of HF-WBI in other types of patients."

https://www.astro.org/Clinical-Practice/Guidelines/Whole-Breast-Fractionation.aspx

Only 11% received chemo in the Whelan study and it was mostly CMF

http://www.nejm.org/doi/full/10.1056/NEJMoa0906260

 

[seper]

thanks... glad ASTRO left the highr grade issue out.
What's this Mednet website?

 

[Palex80]

Start B also allowed for regional irradiation with hypofx.
Based ob the assumption that patients who got regional rt probably got chemo too, one could suggest that regional hypofx rt seems safe.

We offer hypofx to all postmenopausal parients older than 50, who are getting breast +/- supraclavicular lymphatics. I am still a bit reluctant to offer it fir axillary rt too, but it's probably safe.

We use start b schedule up to 39.9 Gy, which is a bit less than the 42.5 Gy. Therefore we generally boost with 4-5x fractions of 2.66 Gy.

I agree with those saying that the only reason hypofx has not becone standard of care is money. We should probably wait till the more extreme hypofx trials from the UK come out, I recall one testing 5 fractions for wbrt.

 

[medgator]

Start B also allowed for regional irradiation with hypofx.
Based ob the assumption that patients who got regional rt probably got chemo too, one could suggest that regional hypofx rt seems safe.

We offer hypofx to all postmenopausal parients older than 50, who are getting breast +/- supraclavicular lymphatics. I am still a bit reluctant to offer it fir axillary rt too, but it's probably safe.

We use start b schedule up to 39.9 Gy, which is a bit less than the 42.5 Gy. Therefore we generally boost with 4-5x fractions of 2.66 Gy.

I agree with those saying that the only reason hypofx has not becone standard of care is money. We should probably wait till the more extreme hypofx trials from the UK come out, I recall one testing 5 fractions for wbrt.

Litigation in Europe is probably not as much of an issue either I imagine, especially when it is UK data we're talking about

 

[Palex80]

It really depends on the country you work.
We get paid per fraction plus a fee fir planning. So hypofractionation will hurt us too, financially speaking.
On the other hand going from 25 to 15 fractions for breast is less a concern, than going down to 5 fractions (as per UK trial), which may become standard of care in 10 years or so.