Background: The safety of inter-sphincteric resection (ISR) for low rectal cancer with adverse histologic subtypes has been incompletely studied. The present study aims at determining the risk of local recurrence with this procedure in poorly differentiated and signet ring cell (PDSR) adenocarcinoma.
Methods: Retrospective analysis from a single tertiary cancer centre of non-metastatic primary rectal cancer <6 cm from the anal verge that underwent ISR. Competing risk analysis and sub-distribution hazard ratios for local recurrence free survivals were calculated to determine factors that influenced local recurrence with the competing risk of death from any cause to overcome the exceeding risk of distant metastasis associated with adverse histologic types.
Results: One hundred forty-two patients underwent ISR and 22.6% has PDSR histology. At a median follow up of 61 months, 15.6% of the PDSR cohort developed local recurrence (five patients) compared to 11.7% in the non-PDSR group. PDSR histology influenced overall and disease free survival but not local recurrence on cox regression. On competing risk analysis, only ypT stage ≥3 predicted worse local recurrence free survival and not histology.
Conclusions: The presence of PDSR histology did not increase the risk of local recurrence after ISR in this retrospective competing risk analysis.
Keywords: Signet ring cell cancer; inter-sphincteric resection; local recurrence; low rectal cancer; poorly differentiated adenocarcinoma.
© 2021 Royal Australasian College of Surgeons.