Lung cancer patients who are asymptomatic at diagnosis show favorable prognosis: A Korean Lung Cancer Registry Study

Purpose and methods: The outcomes of lung cancer patients who were asymptomatic at diagnosis have never been reported as part of a large-scale study. A national survey of lung cancer in South Korea registered a total of 8788 patients diagnosed in 2005. We report the results herein, with an emphasis on the prognosis of the asymptomatic lung cancer patients. Results: Adenocarcinoma was the most frequent (36.1%) histopathologic type, followed by squamous cell carcinoma (32.1%), large cell carcinoma (1.5%), and small cell carcinoma (13.5%). In most cases, lung cancer was detected with subjective symptoms, but 6.5% of cases had no symptoms indicative of lung cancer at the time of diagnosis. Compared to symptomatic patients, asymptomatic patients were younger, more often female, non-smokers, and more frequently presented with adenocarcinoma. Initial treatments were surgery (22.1%), radiation therapy (7.8%), chemo-radiation therapy (5.4%), and chemotherapy (38%), while 26.6% of patients were recorded to have supportive care only. Asymptomatic patients received surgery in 60.0% of cases, and they showed significantly longer survival times than symptomatic patients. Absence of symptoms at diagnosis significantly reduced the risk of death from non-small cell lung cancer, regardless of patient age, patient gender, stage at diagnosis, smoking history, or whether treatment was performed, but did not reduce the risk of death from small cell lung cancer. Conclusions: Adenocarcinoma has grown to be the leading histopathologic type of lung cancer in South Korea. Absence of symptom at diagnosis is a favorable prognostic factor for patients with non-small cell lung cancer.