Lung Cancer Histology and Staging
*Workup for a nodule that is concerning:
**Ensure there is a dedicated CT scan of the chest to evaluate
**Try to obtain old imaging; the rate of change is important
**Can get PET, but even if a lesion if not FDG-avid, but growing quickly we should consider biopsy anyway
**Referral to pulmonary medicine, who can assist with biopsy and also regional lymph node evaluation (important – more below)
**PFTs are often ordered because it provides information about lung function in anticipation of possible surgery for treatment
Lung Cancer Histology:
*Non-small cell lung cancer (NSCLC)
**Umbrella term for a variety of cancers
**Increased risk in smokers
**More common types:
***Adenocarcinoma (~50% of all lung cancers)
****Most common overall; cancer of the mucus producing cells
****IHC: TTF-1, NapsinA, CK7 positive
***Squamous Cell Carcinoma (22.7%)
****More often seen in patients with a smoking history
****IHC: p63 positive and cytokeratin pearls
***Remaining ~15% are the other types of lung cancer / mixed histologies
**Small cell lung cancer (SCLC)
***Neuroendocrine tumor with very different pathology
***Much more aggressive than NSCLC
***Oncologic emergency
***IHC: Chromogranin and synaptophysin positive
IHC pearls: TTF-1 usually means lung cancer (but can be negative in squamous cell lung cancer). This will be important in the future (we promise :])
*Staging for NSCLC:
**Nodal evaluation: lymph node evaluation is part of the workup for NSCLC
**Single digit = central/mediastinal nodes (higher risk)
**Double digit = peripheral/hilar/intrapulmonary lymph nodes (lower risk)
**“R” vs. “L” is direction
*Pearl: Why is this important? If there is nodal involvement, systemic therapy is going to be necessary
*Putting it all together:
**T: Tumor size: T1-4
**N: Nodal involvement
***N0: no nodal involvement
***N1: Nodes closest to the primary tumor (double digits)
****Ipsilateral peribronchial, hilar, intrapulmonary
***N2: Further away (single digit)
****Ipsilateral mediastinal and/or subcarinal LN
***N3: Contralateral any node or supraclavicular LN
**M: Metastasis – in lung cancer, patients with certain patterns of metastatic disease are still curable!
***M0: no mets
***M1a: Contralateral lobe, pleural effusion or pericardial effusion à these are generally still curable!
***M1b: single site of metastatic disease à these are generally still curable!
***M1c: multiple sites of metastatic disease à these are generally not curable
*Staging for SCLC:
**Limited stage - meaning it can fit in “one radiation field”
**Extensive stage - does not fit in “one radiation field”
*Once lung cancer is diagnosed:
**Go to NCCN to learn the flow of ongoing management
**Complete staging (if not already done):
***CT C/A/P (don’t necessarily need if a PET scan is done)
***PET Scan
***MRI brain à in general this is needed, but there are some exception to this (see NCCN)
**Referral to pulmonary for nodal evaluation
References:
NCCN.org
https://doi-org.proxy.library.vanderbilt.edu/10.1016/j.semcancer.2017.11.019-Article about IHC markers for lung cancer
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