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Cough and moderate hoarseness

Reviewed by Karl J. D'Silva, MD

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A 56-year-old woman presents with dyspnea, a persistent cough, and moderate hoarseness. She has no significant medical history other than thyroiditis. Her current medications include hormone replacement therapy (HRT). Although the patient reports a 20–pack-year history of smoking tobacco, she notes that she quit 11 years ago and has not been previously screened for lung cancer. A chest radiograph is ordered, which demonstrates a mass in the upper lobe of the right lung.

What is the likely diagnosis?

Small cell carcinoma

Non–small cell adenocarcinoma

Thymoma

Thymic carcinoma

Primary pleural mesothelioma

Based on the patient's presentation, history, and imaging results, the likely diagnosis is non–small cell lung cancer (NSCLC) of an adenocarcinoma subtype. NSCLC accounts for about 80% of all lung cancer cases. Adenocarcinoma, in particular, is the most common type of lung cancer in the United States, accounting for about 40% of cases. This subtype is also the most common histology among nonsmokers. Still, individuals aged 55 to 77 years with a smoking history of 30 pack-years or more are considered to be the highest-risk group for lung cancer; those who quit less than 15 years ago — like the patient in the present case — are still considered to be in this risk group. Most cases of lung cancer are diagnosed at a late stage when symptoms have already begun to manifest. However, it should be noted that women are more likely to develop adenocarcinoma, are generally younger when they present with symptoms, and are more likely to present with localized disease. It remains to be proven whether the use of HRT affects the risk for lung cancer in women. Deaths from lung cancer, and in particular NSCLC, were shown to be higher among patients undergoing HRT, though no increase in lung cancer death was reported in women receiving estrogen alone.

In addition to the imaging described in this case, workup for NSCLC should include immunohistochemical (IHC) analyses to identify tumor type and lineage (adenocarcinoma, squamous cell carcinoma, metastatic malignancy, or primary pleural mesothelioma). Separate IHC analyses are then used to guide treatment decisions, identifying whether anaplastic lymphoma kinase inhibitor therapy or programmed death-ligand 1 inhibitor therapy would be appropriate.

Tissue should also be conserved for molecular testing. Management of NSCLC is primarily informed by the presence of targetable mutations. Among adenocarcinoma cases, the most common mutations are in the EGFR and KRAS genes. KRAS mutations, unlike EGFR mutations, are associated with a history of smoking and are considered prognostic biomarkers. Because overlapping targetable alterations are uncommon, patients who are confirmed to be harboring KRAS mutations will likely not benefit from additional molecular testing. Presence of the KRAS mutation suggests a poor response to EGFR tyrosine kinase inhibitors, though it does not appear to impact chemotherapeutic efficacy. Although no targeted therapies are yet available for this population, immune checkpoint inhibitors appear to be beneficial. National Comprehensive Cancer Network guidelines advise that all patients with adenocarcinoma be tested for EGFR mutations and that DNA mutational analysis is the preferred method.

Karl J. D'Silva, MD, Clinical Assistant Professor, Department of Medicine, Tufts University School of Medicine, Boston; Medical Director, Department of Oncology and Hematology, Lahey Hospital and Medical Center, Peabody, Massachusetts.

Karl J. D'Silva, MD, has disclosed no relevant financial relationships.

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