Would you use standard neoadjuvant chemoradiation for a patient with advanced rectal cancer and a history of previous pelvic RT for another cancer?

No. We have to remember that the benefit of radiation in locally advanced rectal cancer is limited to a local control benefit; and must balance the risks/benefits as such. Moreover, there are T3 tumors with an uninvolved mesorectal fascia(1) where the role of radiation may be more limited; since a TME with clear margins can be obtained. Also, we can use multiagent chemotherapy like FOLFOX or CAPOX and obtain downstaging(2), and this would be my first approach in an otherwise curable patient.

If ...

In addition to increased R-resection, the benefit of chemoradiation is also in the treatment of non-TME nodes. The MERCURY trial and Deb Schrag's paper are in highly favorable patients (small, High T2, T3 / N0). I would not treat most of those patient with or without prior radiation. However, in the higher risk patients (T3N+, T4, or <5cm from the AV, radial margin threatened), I do treat them even if prior RT. The randomized data do support a LC and OS benefit in patients with T3N+ and T4 disea...