Dose constraints for 7 Gy x 10 hypofractionation for a lung tumor

[RadOnc2013]

What dose constraints do you use when treating a centrally located lung cancer with 7 Gy x 10? I believe the original paper didn't list constraints ... I could be wrong.

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[xrthopeful]

The 10 fraction timmerman table seems to be a good way to go.

 

[FrostyHammer]

https://www.jto.org/article/S1556-0864(15)32359-5/fulltext

 

[OTN]

I've done 67.5 Gy in 10 fractions for tumors directly abutting the esophagus in three patients. All did very well, with some moderate esophageal pain which resolved a few weeks after treatment.

 

[Irradi8or]

Here's a really good one as well:

Stereotactic ablative radiotherapy (SABR) using 70 Gy in 10 fractions for non-small cell lung cancer: Exploration of clinical indications

We report our outcomes for patients with NSCLC treated with SABR to 70Gy in 10 fractions and propose indications for this regimen as well as new dose–…

www.sciencedirect.com

 

[medgator]

70/17 for me

 

[FrostyHammer]

70/17 for me

Data for this non ablative method?

 

[medgator]

Data for this non ablative method?

Phase I study of accelerated conformal radiotherapy for stage I non-small-cell lung cancer in patients with pulmonary dysfunction: CALGB 39904 - PubMed

Accelerated conformal radiotherapy was well tolerated in a high-risk population with clinical stage I NSCLC. Outcomes are comparable to prospective reports of alternative therapies, including stereotactic body radiation therapy and limited resection, with less apparent severe toxicity. Further...

www.ncbi.nlm.nih.gov

 

[deleted1002574]

It’s below 100 BED/non-ablative. Even Bogart himself (“J-Bo”) wouldn’t use it. 70/10 is excellent option for central tumors.

Even though it’s isn’t GI, feel like Chris Crane ready to pounce on this non ablative approach.

 

[medgator]

It’s below 100 BED/non-ablative. Even Bogart himself (“J-Bo”) wouldn’t use it. 70/10 is excellent option for central tumors.

Even though it’s isn’t GI, feel like Chris Crane ready to pounce on this non ablative approach.

ASTRO endorses up to 15 fx https://www.practicalradonc.org/cms...9cada836-cb04-4e95-85eb-697b8da942e6/mmc1.pdf 70/17 is pretty damn close to 100 BED, and a lot safer for those of us in the community. I've had very good control rates using it with minimal morbidity.

Honestly, if something is abutting the esophagus/mediastinum, isn't it a T3/close to a T4? You could argue chemoradiation in those situation and I've done that too with good success. To be frank, I've seen some of these larger central tumors fail with SBRT and do well with chemo/RT. Most SBRT studies include very few large tumors. It's a data-free zone to be sure, but my go to for large (4cm+) lesions has been 2-2.5 Gy/day with carbo/taxol with good results.

 

[deleted1002574]

No. T4 is invading those structures, not abutting. It’s different.

15 fractions isn’t the same as 17. Bogart used large, non-SBRT margins. It’s 2010, no 4D, they did the best they could with the technology they had.

It’s not unreasonable to do, just sub-optimal for local control. It was a phase I study with less than 40 patients. It’s good enough for community patients, I suppose. It’s about 98, which is really close. 70/35 is 84 which is kind of close, but not really there, either. Plus the deceleration which isn’t accounted for.

2Y local control is 96% in the Anderson series which has double the patients. It hasn’t been updated unfortunately. That’s pretty good results. And low toxicity, too.

Stereotactic ablative radiotherapy (SABR) using 70 Gy in 10 fractions for non-small cell lung cancer: exploration of clinical indications - PubMed

SABR with 70 Gy in 10 fractions appears to achieve excellent local control and acceptable toxicity for clinically challenging cases with improved tolerance of the chest wall and brachial plexus as compared with 50 Gy in 4 fractions. This regimen may not be suitable in patients with tumor...

www.ncbi.nlm.nih.gov

Give it a try. You get the benefits of fractionation, the high BED, and good results.

ASTRO endorses up to 15 fx https://www.practicalradonc.org/cms...9cada836-cb04-4e95-85eb-697b8da942e6/mmc1.pdf 70/17 is pretty damn close to 100 BED, and a lot safer for those of us in the community. I've had very good control rates using it with minimal morbidity.

Honestly, if something is abutting the esophagus/mediastinum, isn't it a T4? You could argue chemoradiation in those situation and I've done that too with good success. To be frank, I've seen some of these larger central tumors fail with SBRT and do well with chemo/RT. It's a data-free zone to be sure, but my go to for large (4cm+) lesions has been 2-2.5 Gy/day with carbo/taxol with good results.

 

[medgator]

2Y local control is 96% in the Anderson series which has double the patients. It hasn’t been updated unfortunately. That’s pretty good results. And low toxicity, too.

Stereotactic ablative radiotherapy (SABR) using 70 Gy in 10 fractions for non-small cell lung cancer: exploration of clinical indications - PubMed

SABR with 70 Gy in 10 fractions appears to achieve excellent local control and acceptable toxicity for clinically challenging cases with improved tolerance of the chest wall and brachial plexus as compared with 50 Gy in 4 fractions. This regimen may not be suitable in patients with tumor...

www.ncbi.nlm.nih.gov

Give it a try. You get the benefits of fractionation, the high BED, and good results.

Love the CYA language in the abstract: "This regimen may not be suitable in patients with tumor invading critical central structures."

I'll look into it. Thanks

 

[FrostyHammer]

Phase I study of accelerated conformal radiotherapy for stage I non-small-cell lung cancer in patients with pulmonary dysfunction: CALGB 39904 - PubMed

Accelerated conformal radiotherapy was well tolerated in a high-risk population with clinical stage I NSCLC. Outcomes are comparable to prospective reports of alternative therapies, including stereotactic body radiation therapy and limited resection, with less apparent severe toxicity. Further...

www.ncbi.nlm.nih.gov

This is an old study executed before SBRT was a "thing". For the sake of LC, I would not attempt this regimen, which is largely antiquated in the SBRT era.

 

[medgator]

This is an old study executed before SBRT was a "thing". For the sake of LC, I would not attempt this regimen, which is largely antiquated in the SBRT era.

It's funny to see all this hate on hypofractionation. Yes the bed isn't quite a 100 but the regimen works surprisingly well. I trained with that regimen and sbrt a decade ago. And, as I posted above, Astro endorses 6-15 fx in patients with central lesions who are not felt to be appropriate sbrt candidates.

What do you guys do in the real world with someone coughing on oxygen with a terrible 4DCT who can't even lay on the table long enough to get the sbrt immobilization set up? RFA?!

 

[deleted1002574]

I didn’t know we were talking about patients on oxygen who can’t lay on table long enough. I guess that’s a different conversation. I agree - I would start considering a palliative approach, too.

Nobody is “hating”. 8-10 fractions is still hypofractionation.

There is an approach with probably a 15-20% local control superiority that it sounds like many people are using. If you are happy with 75% control for your community patients, I support you in your endeavors. Nobody said it’s wrong.

 

[medgator]

If you are happy with 75% control for your community patients, I support you in your endeavors. Nobody said it’s wrong.

The paper included multiple bins of patients, so that 75% is likely inaccurate but I digress. I'll certainly look into the 70/10 data, but as someone who trained using 70/17 it has served me quite well in practice

 

[thaddeus]

There is an approach with probably a 15-20% local control superiority that it sounds like many people are using. If you are happy with 75% control for your community patients, I support you in your endeavors. Nobody said it’s wrong.

I'm not sure there is really robust data to support this statement. Lost in the forest of single institution, single arm studies is the SPACE trial, which was randomized and showed no difference in PFS or OS between SBRT (66/3) and good 'ol fashioned conventional fractionation (70/35).

SPACE - A randomized study of SBRT vs conventional fractionated radiotherapy in medically inoperable stage I NSCLC - PubMed

There was no difference in PFS and OS between SBRT and conventionally treated patients despite an imbalance of prognostic factors. We observed a tendency of an improved disease control rate in the SBRT group and they experienced better HRQL and less toxicity. SBRT is convenient for patients and...

www.ncbi.nlm.nih.gov

I'm not proposing anyone treat ultracentral lesions to 70/35, but hypofractionated regimens as low as 60/15 give an EQD2 of at least 70 Gy (depending on which alpha/beta you use). So in the absence of any randomized data showing superior outcomes with more hypofractionated regimens, this humble community doc plans to use 60/15 for lesions abutting esophagus or invading airway in order to minimize risk of toxicity. I'll change my practice if the LUSTRE study shows better outcomes with shorter regimens:

Canadian Phase III Randomized Trial of Stereotactic Body Radiotherapy Versus Conventionally Hypofractionated Radiotherapy for Stage I, Medically Inoperable Non-Small-Cell Lung Cancer - Rationale and Protocol Design for the Ontario Clinical Oncology G

We describe a Canadian phase III randomized controlled trial of stereotactic body radiotherapy (SBRT) versus conventionally hypofractionated radiotherapy (CRT) for the treatment of stage I medically inoperable non-small-cell lung cancer (OCOG-LUSTRE Trial). Eligible patients are randomized in a...

www.ncbi.nlm.nih.gov

Anyway, please explain to me how you plan to meet the MDACC constraint of Dmax < 40 Gy for the esophagus when treating 70/10 to a lesion that is adjacent to the esophagus without massively underdosing the tumor. And don't say protons.

 

[xrthopeful]

If you’re going to bring up SPACE, probably should bring up the more recently published CHISEL right?

https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(18)30896-9/fulltext

 

[evilbooyaa]

I don't really care about SPACE/CHISEL because I'm doing SBRT in this scenario anyways - but some of those CHISEL 'standard fractionation' patients got 50/20 which feels low.

For ultracentral tumors I am more than happy with 60/8. Even 50/5 is not unreasonable. I do agree that regardless of your fractionation scheme, meeting an esophagus constraint if the tumor is in a bad spot will be challenging.

I wouldn't personally do 70/17. Even if somebody was a really poor performance status my focus would be to get them done in the quickest number of fractions reasonably possible, and I think 50/5 would still be my go to. 4DCT, no breath hold or gating to minimize treatment time. The primary issue of ultracentral in terms of toxicity is prox bronchial tree OR esophagus IMO, very rarely both.

 

[deleted1002574]

I'm not sure there is really robust data to support this statement. Lost in the forest of single institution, single arm studies is the SPACE trial, which was randomized and showed no difference in PFS or OS between SBRT (66/3) and good 'ol fashioned conventional fractionation (70/35).

SPACE - A randomized study of SBRT vs conventional fractionated radiotherapy in medically inoperable stage I NSCLC - PubMed

There was no difference in PFS and OS between SBRT and conventionally treated patients despite an imbalance of prognostic factors. We observed a tendency of an improved disease control rate in the SBRT group and they experienced better HRQL and less toxicity. SBRT is convenient for patients and...

www.ncbi.nlm.nih.gov

I'm not proposing anyone treat ultracentral lesions to 70/35, but hypofractionated regimens as low as 60/15 give an EQD2 of at least 70 Gy (depending on which alpha/beta you use). So in the absence of any randomized data showing superior outcomes with more hypofractionated regimens, this humble community doc plans to use 60/15 for lesions abutting esophagus or invading airway in order to minimize risk of toxicity. I'll change my practice if the LUSTRE study shows better outcomes with shorter regimens:

Canadian Phase III Randomized Trial of Stereotactic Body Radiotherapy Versus Conventionally Hypofractionated Radiotherapy for Stage I, Medically Inoperable Non-Small-Cell Lung Cancer - Rationale and Protocol Design for the Ontario Clinical Oncology G

We describe a Canadian phase III randomized controlled trial of stereotactic body radiotherapy (SBRT) versus conventionally hypofractionated radiotherapy (CRT) for the treatment of stage I medically inoperable non-small-cell lung cancer (OCOG-LUSTRE Trial). Eligible patients are randomized in a...

www.ncbi.nlm.nih.gov

Anyway, please explain to me how you plan to meet the MDACC constraint of Dmax < 40 Gy for the esophagus when treating 70/10 to a lesion that is adjacent to the esophagus without massively underdosing the tumor. And don't say protons.

Does anybody think SPACE trial is practice changing? 50 patients on each arm, unbalanced (more T2 in the SBRT arm). I'd be wary using this study to justify anything. I think there is nothing to see here. I would feel very uncomfortable giving 66/33 based on that.

If one can't meet the esophagus constraint, then 60/15 Gy, non-ablative, and make it clear there is a higher chance of local failure. What does protons have to do with it? If you can meet constraints for a central tumor, 70/10 or 50/5 or 60/8 are completely reasonable and associated with great outcomes with a lot of published data.

If they want to compare SBRT to any regimen, it should be chemoRT to 66-70, right?

 

[medgator]

I think 50/5 would still be my go to. 4DCT, no breath hold or gating to minimize treatment time. The primary issue of ultracentral in terms of toxicity is prox bronchial tree OR esophagus IMO, very rarely both.

That's pretty much how I do 70/17. You would still do an sbrt vacloc system?

I would feel uncomfortable treating 10 gy fractions like that.... But maybe I'm just a wimp practicing in the community

 

[FrostyHammer]

That's pretty much how I do 70/17. You would still do an sbrt vacloc system?

I would feel uncomfortable treating 10 gy fractions like that.... But maybe I'm just a wimp practicing in the community

Perhaps a better split is to do the same thing but treat 10 fx in the same manner. No 10 Gy a pop, still get high BED ablation.

 

[scarbrtj]

What do you guys do in the real world with someone coughing on oxygen with a terrible 4DCT who can't even lay on the table long enough to get the sbrt immobilization set up? RFA?!

* Interesting but kind of off-topic. That said, when it comes to palliation...
* I like 17 Gy/2 fx. Underrated.
* One interesting tidbit: no spinal cord toxicity but (probably) large portions of cords got 17/2. I.e., technique very amenable to quick-and-dirty 2 field setups.

 

[taserlaser]

* Interesting but kind of off-topic. That said, when it comes to palliation...
* I like 17 Gy/2 fx. Underrated.
* One interesting tidbit: no spinal cord toxicity but (probably) large portions of cords got 17/2. I.e., technique very amenable to quick-and-dirty 2 field setups.

Just started at a Centre that does a lot of 17/2. Seems to work well in practice, and is indeed very practical.

 

[medgator]

* Interesting but kind of off-topic. That said, when it comes to palliation...
* I like 17 Gy/2 fx. Underrated.
* One interesting tidbit: no spinal cord toxicity but (probably) large portions of cords got 17/2. I.e., technique very amenable to quick-and-dirty 2 field setups.

Symptomatic because of copd, or bad djd etc. Not cancer. Becomes difficult to immobilize them and do 4dct/sbrt in those situations sometimes. I'd still try to treat the cancer definitively in those situations if early stage. 17/2 is interesting, heard about that in residency

 

[scarbrtj]

Just started at a Centre that does a lot of 17/2. Seems to work well in practice, and is indeed very practical.

Have had on more than one occasion the nice but radiobiologically awkward situation where the ICU patient I palliated with 17/2 is referred back by med onc 1-3 months later, looking much better, as an outpatient and asking for more RT.

 

[evilbooyaa]

That's pretty much how I do 70/17. You would still do an sbrt vacloc system?

I would feel uncomfortable treating 10 gy fractions like that.... But maybe I'm just a wimp practicing in the community

Yes. 4DCT evaluates full range of tumor motion for ITV creation + 5mm PTV. Pretty standard treatment for my institution. Not all SBRT requires intense motion management.

It does require patients to be able to lie flat and raise their arms over their head (so if you're talking about that specific patient population then OK), but we can provide supplemental oxygen as necessary for comfort. VacLoc, arms over head, no full body wrap is our standard immobilization for lung SBRT.

 

[scarbrtj]

oh
17/2 was one of the classic uk mrc lung trials

A Medical Research Council (MRC) randomised trial of palliative radiotherapy with two fractions or a single fraction in patients with inoperable non-small-cell lung cancer (NSCLC) and poor performance status. Medical Research Council Lung Cancer Work

Two policies of palliative thoracic radiotherapy for NSCLC have been compared in a randomised multicentre controlled trial aimed at simplifying the palliative treatment of patients with poor performance status. A total of 235 patients were entered. They ...

www.ncbi.nlm.nih.gov

one of my older bosses used to talk about it

It was debuted in Phase III fashion in an antediluvian, non-hypofractionated age. An age that recognized the remunerative value of more fractions I suppose. I recall Turrisi, the study's editorialist (I'm not Googling this, I'm remembering it correctly I hope) saying something like "The hand quivers when writing 17 gray in 2 fractions" or some such. How quaint. Nowadays, the hand quivers when writing more than two fractions.

It does require patients to be able to lay flat

Lay? Tell me lies tell me sweet little lies.

 

[evilbooyaa]

Lay? Tell me lies tell me sweet little lies.

Noted. Master of pedantry as always scarb. Edited above.

That being said, given how poor the functional status is on some of these SBRT patients, having my therapists lay them down flat may be the more correct terminology.

 

[scarbrtj]

Noted. Master of pedantry as always scarb. Edited above.

That being said, given how poor the functional status is on some of these SBRT patients, having my therapists lay them down flat may be the more correct terminology.

Heh. Is grammar pedantry?! "Lay them down" is perhaps acceptable, especially the abulic "them."

 

[medgator]

Grade 5 toxicity at the R hilum with 7.5x8

Illustration of a fatal radiation-induced lung aneurysm: Is central lung stereotactic radiotherapy to be banned?

Stereotactic body radiation therapy is still controversial for inoperable patients with central lung lesion. We report the case of a 59-year-old woman…

www.sciencedirect.com

Probably could have argued to treat R hilar nodal disease with chemo-rt which is what I would have done, personally.

If med onc refused chemo (honestly pretty much anyone can tolerate carbo/taxol if you dose reduce enough), it would have been 70/17 from me

 

[radoncgrad2019]

 

[radoncgrad2019]

The paper is nonsense and is bad propaganda

I agree bad oncologic treatment but bad delivery too

The dose is fine

 

[radoncgrad2019]

 

[taserlaser]

Biopsies in the peri-radiation field really should be contraindicated and yet they always happen... have seen too many patients get referred to GI during/post pelvic/prostate RT. Biopsy nevertheless gets done - poof! Fistula If it’s cancer, it already got RT, let it respond. And yes, RT always gets the blame instead of what is clearly a cofactor.

 

[evilbooyaa]

Grade 5 toxicity at the R hilum with 7.5x8

Illustration of a fatal radiation-induced lung aneurysm: Is central lung stereotactic radiotherapy to be banned?

Stereotactic body radiation therapy is still controversial for inoperable patients with central lung lesion. We report the case of a 59-year-old woman…

www.sciencedirect.com

Probably could have argued to treat R hilar nodal disease with chemo-rt which is what I would have done, personally.

If med onc refused chemo (honestly pretty much anyone can tolerate carbo/taxol if you dose reduce enough), it would have been 70/17 from me

In the RE-IRRADIATION setting.

Patient had initially received surgery, chemoradiation (fractionated), and adjuvant chemotherapy.

At time of hilar recurrence, patient received SBRT.

There is data on risk of aortic rupture when using SBRT for re-irradiation in the lung that people should pay attention to and dose paint accordingly around the aorta: Aortic Dose Constraints when Reirradiating Thoracic Tumors

And yes, if the patient had not undergone biopsy they most likely would not have ruptured. And yes, why is a thermoplastic mask being used for lung immobilization.

The conclusion of the article that was posted was that SBRT should NOT be banned. This is clickbait on the level of buzzfeed (from Twitter).

*EDIT* - I realize that I misread the methods, thanks to @BobbyHeenan . This was the patient's first course of radiation to the hilar area. Patient previously had an unknown primary of the neck that was treated with surgery, chemoRT, and adjuvant chemotherapy. Brainfart on my end. Will leave the post to document my stupidity.

BED calcs for Aorta should still be considered. There are great vessel constraints that we are unaware if they were met. Perhaps 60/8 does lead to some risk of aneurysm development. Perhaps there is some non-zero risk, but futzing about with biopsy of inflamed area certainly did not help the situation.

 

[deleted1002574]

What a misinterpretation of the case report. Thanks for clarification.

Any grade 5 toxicity should give us pause, but should be looked at in context. I would never do 60/8 after CRT in a non-clinical trial setting. No sir.

 

[Burt Radnolds]

I have used long thermoplastic masks in lung for apical tumors or in patients with shoulder mobility issues who I am treating arms down. This is not apical and I can't see their arms in the picture but doesn't sound that insane to me.

 

[BobbyHeenan]

In the RE-IRRADIATION setting.

Patient had initially received surgery, chemoradiation (fractionated), and adjuvant chemotherapy.

At time of hilar recurrence, patient received SBRT.

There is data on risk of aortic rupture when using SBRT for re-irradiation in the lung that people should pay attention to and dose paint accordingly around the aorta: Aortic Dose Constraints when Reirradiating Thoracic Tumors

And yes, if the patient had not undergone biopsy they most likely would not have ruptured. And yes, why is a thermoplastic mask being used for lung immobilization.

The conclusion of the article that was posted was that SBRT should NOT be banned. This is clickbait on the level of buzzfeed (from Twitter).

Was the prior radiation to the lung/hilum or to the head/neck?

I was under the impression this was the first time they had done hilar nodal XRT.

====

Aside - I struggle with these cases all the time. I used to be a big 70 Gy in 17 guy for some of these central tumors, but had a local recurrence using that regimen recently so I somewhat soured on it. Of course N=1 (or 1 failure in 4-5 patients treated this way in the past 5 years).

So I've been doing 60-70 in 10 and even with that I sometimes can't meet local constraints on proximal bronchial tree. Cancer is mean too, if the tumor is aggressive then a local failure means death too, so if you under treat you're in trouble. Many patients can't have chemo, so what dose/fractionation for central or ultra central is really tough and like we've talked about here before, if you're rigid on your "this is the best way to do it" paradigm then you're that way not because of strong data, because lots of reasonable approaches here.

 

[Mandelin Rain]

like we've talked about here before, if you're rigid on your "this is the best way to do it" paradigm then you're that way not because of strong data, because lots of reasonable approaches here.

So true of so many discussions had on this board.

 

[deleted1002574]

Totally. My mind’s changed. I’d do 70/17, thanks gator!

 

[medgator]

Was the prior radiation to the lung/hilum or to the head/neck?

I was under the impression this was the first time they had done hilar nodal XRT.

====

Aside - I struggle with these cases all the time. I used to be a big 70 Gy in 17 guy for some of these central tumors, but had a local recurrence using that regimen recently so I somewhat soured on it. Of course N=1 (or 1 failure in 4-5 patients treated this way in the past 5 years).

I also thought this was upfront radiation to N1 disease.

I've followed many of my patients using the 70/17 regimen for several years now and have not personally seen a recurrence.

That being said, I reflexively will push for chemo-rt for any patients with T3 or N1 disease, including those with central disease and have had good outcomes with minimal toxicity using that approach. I reserve 70/17 for anything else.

T3 and large T2 lesions are underrepresented in sbrt data with some data suggesting poorer outcomes with sbrt at >4cm size therefore I do not see SBRT as the slam dunk choice for this group of patients.

 

[evilbooyaa]

Was the prior radiation to the lung/hilum or to the head/neck?

I was under the impression this was the first time they had done hilar nodal XRT.

====

Ah, you're right. I misread. I thought it was unknown primary of the lung. Will edit my post.

I personally would still favor 60/8 if I could meet the constraints from the LUSTRE trial

 

[RickyScott]

Grade 5 toxicity at the R hilum with 7.5x8

Illustration of a fatal radiation-induced lung aneurysm: Is central lung stereotactic radiotherapy to be banned?

Stereotactic body radiation therapy is still controversial for inoperable patients with central lung lesion. We report the case of a 59-year-old woman…

www.sciencedirect.com

Probably could have argued to treat R hilar nodal disease with chemo-rt which is what I would have done, personally.

If med onc refused chemo (honestly pretty much anyone can tolerate carbo/taxol if you dose reduce enough), it would have been 70/17 from me

A

I also thought this was upfront radiation to N1 disease.

I've followed many of my patients using the 70/17 regimen for several years now and have not personally seen a recurrence.

That being said, I reflexively will push for chemo-rt for any patients with T3 or N1 disease, including those with central disease and have had good outcomes with minimal toxicity using that approach as well.

T3 and large T2 lesions are underrepresented in sbrt data with some data suggesting poorer outcomes with sbrt at >4cm size therefore I do not see SBRT as the slam dunk choice for this group of patients.

I also like that approach and have good results.

 

[Burt Radnolds]

I think 70/17 is appropriately aggressive and would have a very good chance at prolonged control of most tumors. I laugh at the BED shamers who love to throw around terms like "non ablative" when more often than not, I would argue this would be ablative. (maybe I missed the dictionary entry ab·la·tive: possessing a BED of not 1 cGy less than 100 Gy a/b = 10??). Additionally, to appropriately use some of those higher BED regimens, you have to essentially cool off the OAR to the point you are underdosing in my experience. I have tended to use 60/15 for some of these and have had good success with that regimen as well, which is even less BED wise, but is supported in ASTROs consensus SBRT document (direct quote, "for central tumors for which SBRT is deemed too high risk, hypofractionated radiation therapy utilizing 6 to 15 fractions can be considered.") Maybe I'll bump it up a notch to 70/17. Shame away!

 

[Mandelin Rain]

I can't imagine there are too many carcinomas that you can't control treating 70Gy in 17 fractions that you can treating 70Gy in 10 fractions. In either case, recurrence is likely related to marginal miss, underdosing due to OAR, or metastatic disease. If the 17 fraction allows a slightly more generous volume, I'd posit that head to head, it may have a higher LC.

 

[taserlaser]

I think 70/17 is appropriately aggressive and would have a very good chance at prolonged control of most tumors. I laugh at the BED shamers who love to throw around terms like "non ablative" when more often than not, I would argue this would be ablative. (maybe I missed the dictionary entry ab·la·tive: possessing a BED of not 1 cGy less than 100 Gy a/b = 10??). Additionally, to appropriately use some of those higher BED regimens, you have to essentially cool off the OAR to the point you are underdosing in my experience. I have tended to use 60/15 for some of these and have had good success with that regimen as well, which is even less BED wise, but is supported in ASTROs consensus SBRT document (direct quote, "for central tumors for which SBRT is deemed too high risk, hypofractionated radiation therapy utilizing 6 to 15 fractions can be considered.") Maybe I'll bump it up a notch to 70/17. Shame away!

Yeah, in my training I used a lot of 60/15 for ultra central. Now that more data is coming out though, I do want to personally spend some more time looking at other dose regimens and see where things sit. 70/17 is something I haven’t used before, but I have an open mind.

 

[scarbrtj]

I think 70/17 is appropriately aggressive and would have a very good chance at prolonged control of most tumors. I laugh at the BED shamers who love to throw around terms like "non ablative" when more often than not, I would argue this would be ablative. (maybe I missed the dictionary entry ab·la·tive: possessing a BED of not 1 cGy less than 100 Gy a/b = 10??).

OF COURSE this is correct. As rad oncs we are pretty dang smart & powerful... but are we allowed to make up new definitions for words? If an XRT dose causes a tumor to go away, it's ablative no matter how big the dose was. How about when you have a local recurrence after an "ablative" dose? Guess that wasn't so ablative. Tumor responses (aka "ablation") to ionizing radiation will always be stochastic and lie on a continuum. No need to appeal to some mysterious radiobiologically ablative force. If one wants to get picky, the ultimate fate of all irradiated tumors (or bruises... or any dead cell) is vaporization (ablation), pooping, or peeing.

 

[Mandelin Rain]

I'm firing up the old 70Gy in 17 fraction regimen for the first time for a central moderate sized tumor. Any suggestions for constraints to the aorta/bronchial tree from the people who have used this before? They were not specified in CALGB 39904

 

[evilbooyaa]

While I don't routinely do 70/17, would consider 15fx constraints until somebody can provide 17fx ones:

theMednet

www.themednet.org

Timmerman also has constraints in a supplemental table from his phase I - Precision Hypofractionated Radiation Therapy in Poor Performing Patients With Non-Small Cell Lung Cancer: Phase 1 Dose Escalation Trial