How would you approach a low-lying rectal cancer wtih para-aortic lymphadenopathy?

I will assume that the question is one of management for oligometastatic nodal M1 disease--i.e. one or two para aortic lymph nodes and no other extrapelvic disease. In the past I've treated a few cases like this, as well as a few that were M1 by virtue of inguinal or iliac nodal metastases. The combination of conventionally fractionated RT with concurrent 5FU monotherapy followed by surgical resection and more chemotherapy did yield a few long term survivors. However many of the patients treated this way would develop disappointingly widespread distant metastatic disease very rapidly.

Therefore, although I still think that a combination of RT, chemo, and surgery is an acceptable management option for oligometastatic rectal cancer, including...

I agree with Bob's comments about the integration of radiation with chemotherapy. I wanted to emphasize the point that that the peraaortic nodal chain is a regional nodal volume and disease can sometimes be isolated there. If you think that the disease could be isolated to the periaortics, it is important to considering elective nodal radiation to the periaortic lymph nodes rather than SBRT to the nodes only. The only real toxicity risk potentially comes from the treatment of the transverse duodenum, so I tend to be inclusive when considering microscopic nodal coverage. The easiest way to accomplish this treatment is with a simultaneous integrated boost IMRT technique. If the disease is not directly abutting the GI tract, it is possible to ...

I would definiitely use IMRT. I think one can do a much better job limiting dose to bowel and kidneys with IMRT vs. 3D. While the choice of IMRT over 3D might increase the volue receiving low doses, when the prescription dose is 25Gy/5fx to the high dose regions and 20Gy/5fx to elective regions, the non trageted regions will be receiving well under ~10Gy/5fx with IMRT. With a 3 or 4 field approach, one will often have non-targeted hot spots above that range. I've never tried more than 4 fields for 3D planning for a pelvis+para aortics target volume.

Re the question of short course RT vs a longer, more fractionated dose prescription, there is one scenario in which I would strongly consider a more fractionated, higher total dose approach. Wh...