Trends and Updated Statistics of Lung Cancer in Korea

The clinical characteristics and prognostic factors of patients with lung cancer are expected to differ with respect to geographical differences from the past to the future. In the Republic of Korea, a few national lung cancer surveys have been conducted. In 1997, Lee et al. performed the first survey. Among 3,794 patients, they found that the most frequent symptom was cough (57.2%), and asymptomatic patients accounted for only 7.2% of all patients. Smokers, including current and ex-smokers, accounted for 76.5% (89.8% male and 25.4% female). Considering the high smoking rate, it is reasonable to think that the tumor was mainly located in the central lung region, and the major results of histopathological assessment were squamous cell carcinoma (44.7%) and small cell cancer (16.8%). Therefore, the principal diagnostic tool was bronchoscopic biopsy. In contrast, percutaneous needle biopsy was the main tool for the diagnosis of adenocarcinoma (27.9%), which usually occurred in the peripheral lung region. Advanced stages IIIB and IV disease were detected in 65.3% of patients with non-small cell lung cancer (NSCLC). In 2005, In et al. performed the second survey. Among the total of 8,788 patients, they found that cough (38.1%) was still the most frequent symptom, and 6.5% of the patients had no subjective symptoms. These asymptomatic patients were of younger age, more often female, non-smokers, and more commonly had adenocarcinoma. These asymptomatic patients displayed significantly better prognosis from NSCLC as they exhibited earlier stage of disease (stage I–II, 61.3%; stage III, 22.1%; and stage IV, 16.6%) than symptomatic patients (stage I–II, 22.3%; stage III, 35.4%; and stage IV, 42.4%). Sixty percent of asymptomatic patients could undergo surgery, whereas only 19.3% of symptomatic patients could undergo surgical treatment. In et al. also reported that 40.5% of the patients were current smokers, followed by 30.6% former smokers and 28.9% never-smokers, whereas only 20.3% of female patients with lung cancer had a smoking history. Compared to the results of the first national survey, the proportion of female patients with lung cancer increased from 20.7% to 24.2%, and the incidence of never-smokers also increased from 23.5% to 28.9%. In contrast to the results of the first national survey, adenocarcinoma (36.1%) was the most common result of histopathological assessment, followed by squamous cell carcinoma (32.1%) and small cell carcinoma (13.5%). The leading histopathologic subtype had changed from squamous cell carcinoma to adenocarcinoma. Shin et al. obtained data from the Korea Central Cancer Registry (1999–2012) and Statistics Korea (1983–2013). They reported that the Korean lung cancer mortality began to decrease in 2002. Among patients diagnosed between 1993– 1997 and 2008–2012, the overall 5-year relative survival rates improved significantly from 11.2% to 19.3% in men and 14.7% to 28.2% in women, respectively. Recently, Kim et al. conducted a pilot study using data of the Korean nationwide lung cancer registry. Among the 23,254 new patients with lung cancer enrolled in the Korea Central Cancer Registry in 2013, a total of 489 patients from 19 hospitals were evaluated in terms of clinical characteristics, histopathology, and prognostic factors. The clinical data including age, sex, body mass index, smoking history, symptoms, performance status, histopathologic type, clinical staging, epidermal growth factor receptor (EGFR) mutation status, initial treatment modality, and survival status were retrospectively analyzed until December 2015. They found that the Trends and Updated Statistics of Lung Cancer in Korea