indication of PORT for abdominal leiomyosarcoma

[Kroll2013]

66yo female patient, that had a complete resection of a left iliac vein STS.
Pathology: Leiomyosarcoma, grade 1, tumor size 7cm, R0 neg margins, Ki proliferation index >5%
is there an indication for post-operative RT?

thank you

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[Palex80]

NCCN says no (RETSARC-3).

I'd still discuss it with the patient. Was it an "oncologic resection"? Does the patient have lymphedema?

Cheers, Alex

 

[Kroll2013]

NCCN says no (RETSARC-3).

I'd still discuss it with the patient. Was it an "oncologic resection"? Does the patient have lymphedema?

Cheers, Alex

Thk you alex. It is an oncologic resection with no lymphedema.

 

[seper]

I looked at NCCN guidelines and to my surprise - grade does not matter; positive margin does not reqiure XRT. I wonder where the data to support this is coming from.

 

[napoleondynamite]

I wouldn't radiate. Distant failure risk is probably much higher than locoregional failure. And I also just don't believe that a dose of 45-50Gy would ablate microscopic disease for this histology, if it's there.

 

[radiaterMike]

I think locoregional failure is a much greater risk but not strong evidence that post op radiation helps.

 

[napoleondynamite]

errgh I misread the orginal post - I thought this was a uterine LMS

Anyway, I retract my statement. I actually would radiate here. Not strong evidence, but location trumps grade IMO and this was likely peeled off the vein. Would be reasonable to wait and watch closely for a recurrence - then pull the trigger with a more clear target down the line. One advantage to that approach is possibly lower doses later if surgery is an option down the road once again..preop then surgerize. If you go that route, I'd image q3 months. If you radiate now, I'd go as high as surrounding organs will let you.

 

[radiaterMike]

I should retract part of my post too. Local recurrence predominates as regional/nodal failure is rare. Thus the fields can be fairly localized.

 

[Palex80]

I looked at NCCN guidelines and to my surprise - grade does not matter; positive margin does not reqiure XRT. I wonder where the data to support this is coming from.

That is indeed the case for abdominal & retroperitoneal sarcomas according to NCCN. This is probably based on the scarce evidence for this disease.
The tricky question is if you would treat this tumor as an abdominal sarcoma or a trunk sarcoma.

Guidelines for trunk sarcoma do take into consideration tumor grading.

 

[seper]

I personally would irradiate any large sarcoma with margins < 1 cm.

 

[Phantom1]

Agree that local failure will predominate given that histology and low grade, low ki-67. The traditional post-op dose for sarcoma is 60Gy or more and so given the location you may not be able to achieve that dose due to bowel constraint. Where I trained we we would not irradiate post-op for low grade intra-addominal/pelvic sarcoma with negative margin. Alternative would be to observe closely, and if she recurs in 4-5 years give pre-op to 50Gy then resect.

 

[seper]

Thinking about, that NCCN chapter totally makes sense. Why give 50 Gy postop when it's likely won't reduce chance of relapse.

 

[Lamount]

At my institution, we would probably opt for observation all things being equal. I agree that, in this instance, the greatest risk of failure is local recurrence. Depending on the location, re-resection may be a possibility. If it recurs, you can consider pre-op XRT -> resection +/- IORT for close/pos margins (depending upon availability). I am a resident and am continuing to learn about management of sarcomas but the factors that would affect my decision are the kinetics of tumor growth and whether or not the location is amenable to re-resection. Alternatively, if this tumor grew quickly and is in a difficult area, I would opt for PORT.