Two-marker protein profile predicts poor prognosis in patients with early rectal cancer

The aim of this study was to establish an immunohistochemical protein profile to complement preoperative staging and identify rectal cancer patients at high-risk of adverse outcome. Immunohistochemistry was performed on a tissue microarray including 482 rectal cancers for APAF-1, EphB2, MST1, Ki67, p53, RHAMM, RKIP and CD8(+) tumour infiltrating lymphocytes (TILs). After resampling of the data and multivariable analysis, the most reproducible markers were combined and prognosis evaluated as stratified by pT and pN status. In multivariable analysis, only positive RHAMM (P>0.001; HR=1.94 (1.44-2.61)) and loss of CD8(+) TILs (P=0.006; HR=0.63 (0.45-0.88)) were independent prognostic factors. The 5-year cancer-specific survival rate for RHAMM+/TIL- patients was 30% (95% CI 21-40%) compared to 76% (95% CI: 66-84%) for RHAMM-/TIL+ patients (P>0.001). The 5-year cancer-specific survival of T1/T2/RHAMM+/TIL- patients was 48% (20-72%) and significantly worse compared to T3/T4/RHAMM-/TIL+ patients (71% 95% CI 56-82%); P=0.039). Stratifying by nodal status, only N+/RHAMM+/TIL- patients demonstrated a significantly worse prognosis than N0/RHAMM+/TIL- patients (P=0.005). Loss of CD8(+) TILs was predictive of local recurrence in RHAMM+ tumours (P=0.009) only. RHAMM and CD8(+) TILs may assist in identifying early stage rectal cancer patients facing a particularly poor prognosis and who may derive a benefit from preoperative therapy.