Broadening the field.
The Study: The problem, of course, is the safe and reliable targeting of at-risk regions coupled with the fact that local control after a large colon resection is typically quite good own its own. Authors at VCU ponder if radiation would be worth its while for the most locally-advanced of cases. Given it’s not technically a standard practice, they turned to SEER data for help. Among nearly 22K patients with non-metastatic pT4 colon cancer invading or adherent to adjacent organs, 1K (~5%) received adjuvant radiation. Overall, cancer-specific survival (CSS) at 5 years was 40%, discriminated best by nodal status: 61% if N0 versus 29% if N1. Now here’s where things get interesting. The primary endpoint of CSS was significantly improved among those receiving adjuvant radiation from 38 → 44%, despite a greater proportion of those receiving radiation having nodal positivity. Indeed, the CSS benefit with radiation held across nodal status: 61 → 71% for N0 and 28 → 34% for N1. Granted this has big potential for bias, adjusting for sex, age, nodal status, and grade demonstrated a 12% relative reduction in cancer death translating to a number needed to radiate of 14. This all may explain the significant overall survival advantage with adjuvant radiation from a median of 34 → 43 months.
Bottom Line: Big data suggests treating 14 patients with adjuvant radiation for pT4 colon cancer saves one life, which is more than we can say for rectal cancer. | McLaughlin, Radiother Oncol 2019