Kidney Cancer Pulmonary Metastases May Hide Primary Lung Cancer Diagnosis

03/27/17

Primary non-small cell lung cancer (NSCLC) may be underdiagnosed in patients with metastatic renal cell carcinoma, according to new research.

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Kidney cancer often metastasizes to the lungs. Thus, the development of a second primary malignancy in the lungs of a patient with a preexisting diagnosis of metastatic renal cell carcinoma may be overlooked or misdiagnosed to progression of disease.

“Lung cancer is typically more aggressive than kidney cancer. Undetected, lung cancer may spread and eventually kill the patient," said James Brugarolas, MD, PhD, director of the Kidney Cancer Program and associate professor of Internal Medicine at the University of Texas Southwestern Medical Center in Dallas, in a news release (March 7, 2017).

Dr Brugarolas and colleagues conducted a retrospective study of 151 patients at the Harold C Simmons Comprehensive Cancer Center who received systemic targeted therapy for metastatic renal cell carcinoma from 2006 to 2013. Researchers calculated the proportion and incidence rate for developing NSCLC with preexisting metastatic renal cell carcinoma. Results were published in Clinical Genitourinary Cancer (published online February 2017; doi:10.1016/j.clgc.2017.01.026).

Analyses showed that 2% (n = 3/151; 95% CI, 0.68-5.58) of patients treated for metastatic renal cell carcinoma with systemic therapies were subsequently diagnosed with NSCLC. The rate increased to 3.5% (n= 3/85; 95% CI, 1.21-9.87) among patients with diagnosed renal cell carcinoma with pulmonary metastasis. The incidence rate for development of NSCLC in patients with metastatic renal cell carcinoma was 0.87 per 100 person-years (95% CI, 0.22-2.4).

Investigators were further able to identify 4 previous cases of kidney cancer metastasizing to the lungs where primary lung cancer already existed, which led them to conclude that other cases of lung cancer in patients with kidney cancer may have gone undiagnosed and underreported. Distinguishing factors between a new primary and progression of metastatic disease, they suggest, may be found in the radiographic appearance and clinical behavior of a tumor.

"Our report raises an important flag for medical oncologists and radiologists to be on the lookout for a hidden lung cancer," said Dr Brugarolas. – Zachary Bessette