Neoadjuvant chemoradiation and rectal cancer.

Area of Science:

• Oncology
• Pathology
• Surgical Pathology

Background:

• Neoadjuvant chemoradiation (NACR) is standard for stage II and III rectal cancer.
• NACR significantly alters rectal cancer specimens, necessitating changes in pathological evaluation.
• Current pathological assessment of NACR-treated specimens shows considerable variation in practice.

Purpose of the Study:

• To review recent developments and challenges in the pathological assessment of NACR-treated rectal cancer specimens.
• To emphasize the need for standardized pathological handling and reporting of these specimens.

Main Methods:

• Overview of pathological adaptations required for NACR-treated rectal cancer specimens.
• Discussion of gross examination, sectioning, and microscopic analysis techniques.
• Review of issues including tumor regression grading and lymph node assessment.

Main Results:

• NACR-treated specimens require consistent handling and generous sampling.
• Microscopic examination must be vigilant for residual cancer cells, often found deep within the bowel wall.
• Acellular mucin pools do not indicate residual tumor and do not upstage the cancer.

Conclusions:

• Standardized pathological evaluation of NACR-treated rectal cancer specimens is essential.
• Careful gross and microscopic examination, with appropriate sampling, is critical for accurate staging.
• A clinically relevant tumor regression grading system should be adopted, and efforts made to identify at least 12 lymph nodes.