Preop short course RT vs Selective Postop CTRT for Rectal Cancer

The Lancet has two articles today reporting the results of the MRC CR07 and NCIC-CTG C016 trials.

The first reports the primary results of the trial:
1350 patients with operable adenocarcinoma of the rectum randomized to
1. 25 Gy in five fractions preop versus2. Selective postoperative chemoradiotherapy (45 Gy in 25 fractions with concurrent 5-fluorouracil) for positive radial marginsMedian follow-up = 4 years. 
61% reduction in the relative risk of local recurrence for patients receiving preoperative radiotherapy (HR 0·39, 95% CI 0·27—0·58, p<0·0001)
3 year reduction in local recurrence was of 6·2% (95% CI 5·3—7·1) (4·4% preoperative radiotherapy vs 10·6% selective postoperative chemoradiotherapy)
Disease-free survival improvement of 24% for patients receiving preoperative radiotherapy (HR 0·76, 95% CI 0·62—0·94, p=0·013
3 years DFS difference of 6·0% (95% CI 5·3—6·8) (77·5% vs 71·5%)
Overall survival did no different (HR 0·91, 95% CI 0·73—1·13, p=0·40)
Thus this suggests that at least currently we are unable to select out patients that might be spared RT.

 The Second is from pathologist Phil Quirke who reports on the surgical quality and it's affect on local recurrence.
1156 patient tumors underwent rigorous pathologic examination:
128 (11%) had + margin
the mesorectal plane was achieved in 604 (52%)
intramesorectal plane in 398 (34%)
muscularis propria plane in 154 (13%)
Negative Margin vs Positive margin: LR Hazard ratio (HR) was 0·32 (95% CI 0·16—0·63, p=0·0011), 3yr LR 6% (5—8%) and 17% (10—26%) respectively
TME LR HR was 0·32 (0·16—0·64), intramesorectal plane LR HR was 0·48 (0·25—0·93). 3yr LR was 4% (3—6%) for TME, 7% (5—11%) for intramesorectal, and 13% (8—21%) for muscularis propria groups.
All subgroups benefited from preop RT.
good TME + preop RT resulted in 3yr LR of 1%Thus good surgery + preop RT results in the best LR rates in this disease.