Phone a pathologist.

Top Line: Not all total mesorectal excisions (TMEs) are created equal.

The Study: First, a refresher. The huge German CAO/ARO/AIO-04 trial randomized >1200 patients with locally-advanced rectal cancer to conventionally-fractionated pre-op radiation with concurrent 5FU → TME → adjuvant 5FU versus the same but with the addition of oxaliplatin both to the neoadjuvant chemoradiation and to the adjuvant 5FU. The final reporting in 2015 demonstrated a disease free survival (DFS) advantage at 3 years from 71% to 75% with the addition of oxaliplatin. Ok great, but let’s talk more about the TME. There’s now reporting on an interesting secondary endpoint, quality of TME planes, which was actually recorded prospectively by the evaluating pathologist—oh, and the operating surgeon for good measure. The possible TME planes were mesorectal (good), intramesorectal (meh), and muscularis propria (not good). Overall rates of the 3 planes per pathologist were 81% (good), 15% (meh) and 5% (not good), with poor quality planes more common with higher tumor stage, tumor location in lower rectum, abdominoperinel resections (APR) as compared with lower anterior resections (LAR), and positive margins. Most importantly, poorer quality planes were significantly associated with worse local control, DFS and even overall survival at 3 years. To top it all off, surgeon-reported planes were associated with...nothing.

Bottom Line: An adequate circumferential plane on the TME specimen plays a big role in outcomes for locally-advanced rectal cancer. And if you’re going to ask about it, ask a pathologist. | Kitz, JAMA Surg 2018