Do not expect an endoluminal complete response to identify a pathologic complete response in rectal cancer!

Area of Science:

• Gastroenterology
• Oncology
• Surgical Pathology

Background:

• Neoadjuvant chemoradiotherapy is a standard treatment for rectal cancer.
• Assessing treatment response is crucial for patient management and prognosis.
• Endoluminal complete response (eCR) is an early indicator, but its correlation with pathologic complete response (pCR) requires further investigation.

Purpose of the Study:

• To investigate the relationship between endoluminal complete response (eCR) and pathologic complete response (pCR) following neoadjuvant chemoradiotherapy for rectal cancer.
• To identify predictors of achieving a pCR (ypT0N0).

Main Methods:

• Retrospective review of 102 rectal cancer patients who underwent neoadjuvant chemoradiotherapy and proctectomy (2013-2017).
• Comparison of endoluminal response with anatomopathological staging.
• Analysis of residual lesion area and tumor location as potential predictors of pCR.

Main Results:

• 20 patients (19.6%) achieved pCR (ypT0N0).
• Of those with pCR, 9 patients (45%) did not achieve eCR.
• eCR demonstrated 55.00% sensitivity, 96.34% specificity, and 88.24% accuracy for predicting ypT0N0.
• Predictors for pCR included eCR, residual lesion area ≤ 4 cm², and mid-rectal tumor location.

Conclusions:

• A significant proportion of patients achieving pCR after rectal cancer chemoradiotherapy do not exhibit eCR.
• Mid-rectal tumors, residual lesion size ≤ 4 cm², and the presence of eCR are significantly associated with achieving pCR (ypT0N0).