Lung Cancer Types and Characteristics

Lung Cancer Types and Characteristics

• Small cell lung cancer (SCLC): Accounts for 15% of cases, highly aggressive, usually central, with a potential for metastasis to the brain, and commonly associated with smoking.
• Non-small cell lung cancer (NSCLC): Accounts for 85% of cases, less aggressive than SCLC. Subtypes include adenocarcinoma (most common, 60%, linked to smoking), and squamous cell carcinoma (less common, 20%, frequently central or peripheral with a greater risk from smoking),.

Adenocarcinoma Subtypes

• Mucinous Adenocarcinoma: Characterized by the presence of mucus.
• Non-Mucinous Adenocarcinoma: Absence of mucus.

Histological Features

• Adenocarcinoma: Usually arises from glandular cells in the peripheral lung, often associated with smoking.
• Squamous Cell Carcinoma: Generally located in the central bronchi, with a high association to smoking.

Molecular Characteristics

• IHC (Immunohistochemistry): Various markers, including CK7, TTF-1, CK AE1/AE3, Ki67 etc, help in diagnosis and classification. Specific markers present in different subtypes.
• Molecular Markers: EGFR, KRAS, ALK, PDL-1, etc, used to determine treatment options with EGFR-TK inhibitors, and Pembrolizumab.
• Ki67: A marker of cell proliferation, high values suggest aggressive tumors.

Neuroendocrine Tumors

• Carcinoid tumors: Typically non-aggressive and have a good prognosis.
• Neuroendocrine neoplasms: May be associated or not with NSCLC or small cell lung cancer. Large cell neuroendocrine carcinoma is often associated with cigarette smoking.
• Typical vs Atypical: Differentiated by mitotic rate, necrosis levels, and atypical cytology; these are key indicators.

Other Important Notes

• Mutations: Specific mutations, particularly in EGFR and KRAS, are common in lung cancers and can influence treatment decisions.
• Smoking Prevalence: A strong link exists between smoking and several lung cancer types, particularly adenocarcinoma and squamous cell carcinoma.