Is the assessment of submucosal invasion still useful in the management of early rectal cancer? A study of 91 consecutive patients.

AIM: The only studies on the prognosis of T1 tumours are old and investigate colic and rectal cancers. Very few studies use Kikuchi's classification (of dividing submucosa into three strata) to evaluate the depth of the submucosal invasion. This study aimed to assess the pathological risk factors for lymph node metastasis (LNM), and the pathological and oncological results of patients with early rectal cancer (ERC, pT1 tumour).

METHOD: Between 2000 and 2014, 91 consecutive patients undergoing surgery [primary total mesorectal excision (TME) or local excision (LE) alone, or LE followed by TME] for ERC were included.

RESULTS: Eighteen patients underwent LE, 22 underwent LE followed by TME and 51 underwent primary total TME. After TME (n = 73), 16 (23%) patients had LNM. The LNM rate was 15% for Sm1 tumours, 14% for Sm2 tumours and 30% for Sm3 tumours. In multivariate analysis, lymphovascular invasion (P = 0.027) and high tumour budding (P = 0.037) were the only independent factors predictive of LNM. The depth of submucosal invasion was not associated with an increased risk of LNM. After a mean follow up of 56 ± 46 months, 5-year overall survival, specific survival and disease-free survival were, respectively, 82%, 93% and 75%. No significant difference of survival was found according to the depth of submucosal invasion or to the surgical management.

CONCLUSION: Histological features seem to be stronger risk factors for LNM than depth of submucosal invasion. Considering the LNM rate, TME should be discussed after LE in terms of one of these pathological criteria.