Pathologic Processing of Lung Cancer Resection Specimens After Neoadjuvant Therapy

Area of Science:

• Oncology
• Pathology
• Cancer Research

Background:

• Neoadjuvant treatment for non-small cell lung cancer (NSCLC) necessitates evaluating treatment efficacy via pathology. Pathologic tumor response metrics like major pathologic response (MPR) and complete pathologic response (CPR) are crucial surrogates for clinical efficacy.
• Current pathologic assessment of residual viable tumor (RVT) is non-uniform, particularly concerning primary tumor sampling, shifting focus from tumor typing to RVT scoring.

Purpose of the Study:

• To analyze the accuracy of %RVT, MPR, and CPR scoring using traditional versus comprehensive tumor submission methods.
• To determine the minimum number of tissue sections required for accurate pathologic response assessment in NSCLC post-neoadjuvant therapy.

Main Methods:

• A simulation study was conducted on 31 pretreated primary lung tumors.
• Pathologic evaluation of %RVT, MPR, and CPR was compared between traditional grossing methods and submitting the entire residual primary tumor (gold standard).
• The minimum number of tumor sections for accurate scoring was identified.

Main Results:

• Traditional grossing yielded accurate %RVT, MPR, and CPR calls in only 52%, 87%, and 81% of cases, respectively.
• Achieving at least 90% accuracy for these parameters requires submitting the entire residual tumor or a minimum of 20 sections.
• Accurate scoring of %RVT, MPR, and CPR is not reliably achievable with traditional tumor grossing methods.

Conclusions:

• Traditional grossing methods are insufficient for accurate assessment of pathologic tumor response in NSCLC treated with neoadjuvant therapy.
• Comprehensive submission of the entire primary tumor, or at least 20 sections, is essential for reliable RVT, MPR, and CPR scoring.
• Standardized and thorough tissue submission protocols are critical for clinical trial interpretation and patient management.