"I was relatively healthy for my age, so I kept working as a daycare helper and always got regular health checkups. I have never touched a cigarette in my life, and no one in my family smokes either."
Yoon, a woman in her 70s whom this reporter met at Yonsei Cancer Center on the 10th, recalled, "When I woke up in the morning my face would swell, and I thought my cough was lasting a long time, but I never imagined it would be lung cancer." The first signs of the illness appeared in July last year. On the advice of those around her, she had X-rays and blood tests at a local clinic, but no abnormalities were found. When there was no improvement for more than a month, she visited a large hospital, where a computed tomography (CT) scan revealed a white lesion in her lung. She was referred to the cancer center, and after undergoing various tests including a brain magnetic resonance imaging (MRI) scan, she was diagnosed with small cell lung cancer.
Lung cancer has remained the leading cause of cancer death in Korea since 2000. According to national cancer registration statistics, 32,953 people were newly diagnosed in 2023, ranking second in incidence after thyroid cancer. Lung cancer is broadly divided into "small cell lung cancer" and "non-small cell lung cancer," depending on the size and shape of the cancer cells seen under a microscope. Small cell lung cancer has long been regarded as the epitome of hard-to-cure cancer. Although it accounts for only about 15–20% of all lung cancers, it proliferates much faster and has a higher recurrence rate than non-small cell lung cancer. Some reports put its five-year survival rate at just about 6%. As of 2023, the number of small cell lung cancer patients in Korea is estimated at about 14,000, with 3,260 new cases. Kim Hye-ryun, Director of the Lung Cancer Center at Yonsei Cancer Center and a professor of medical oncology, explained, "The onset of small cell lung cancer is closely associated with drinking and smoking, but as in this case, cancer can occur even in people who do not drink or smoke at all." She added, "Because the cancer mainly develops around the bronchi, symptoms of difficulty breathing commonly appear."
Small cell lung cancer is classified into "limited stage" and "extensive stage," depending on how far the disease has progressed and the treatment method. Limited stage, diagnosed in about 30% of all small cell lung cancer patients, is a type in which the cancer cells have not spread elsewhere and remain confined to a specific area. Compared with extensive stage, in which the tumor has spread beyond one lung to the opposite lung or to distant organs such as the head or liver, the tumor burden itself is smaller. "When (Yoon) first came in, the tumor was located slightly to the right of the center of her chest," Kim said. "It appears the tumor had invaded the superior vena cava, causing the facial swelling." The superior vena cava is a key pathway that collects blood circulating in the upper body—the face, neck, arms, and upper chest—and returns it to the heart. As the tumor compressed the large blood vessel, blood flow was impaired, producing the classic symptoms of "superior vena cava syndrome," such as facial swelling. Kim said, "The cancer cells had not spread to the opposite side, so it was a limited-stage condition," and proposed, "Let's focus on confining the lesion to a single area as much as possible." Yoon received platinum-based chemotherapy to attack the cancer cells spread throughout her body, undergoing four cycles of three days each on a monthly basis. At the same time, she underwent 30 sessions of radiation therapy, with additional brain radiation therapy to prevent brain metastasis, for a total of 40 radiation sessions. About four months after the high-intensity treatment began, the tumor had shrunk considerably, but Yoon's body grew increasingly weak. She struggled to swallow food and could not eat properly, and having to visit the hospital nearly every day to keep up with the testing and treatment schedule made it even harder to bear.
Because small cell lung cancer proliferates very rapidly, it commonly recurs within about 9–10 months after first-line standard treatment. In the past, once chemoradiation therapy was completed, there was no option other than to monitor the patient's progress until recurrence. This situation changed in April last year, when an immunotherapy drug was approved for limited-stage small cell lung cancer patients whose disease had not progressed after platinum-based chemoradiation therapy. According to Kim, patients who received immunotherapy maintenance therapy for two years after platinum-based chemoradiation had a median progression-free survival (PFS) of 16.6 months, 7.4 months longer than the placebo group (9.2 months). This means that adding immunotherapy allows patients to survive for more than a year and a half without cancer progression, such as the tumor growing again. The median overall survival (OS) of the immunotherapy group reached 55.9 months, 1.7 times longer than the placebo group (33.4 months), and the incidence of severe adverse reactions was at a level similar to that of the placebo group. "Limited-stage small cell lung cancer often recurred within 9–10 months even after high-intensity chemoradiation therapy was completed," Kim explained. "Adding immunotherapy after treatment can lower the risk of recurrence or death by more than 30%, and some patients even achieve a cure without recurrence." Yoon began immunotherapy maintenance therapy late last year and recently completed her seventh dose. However, because it is not covered by national health insurance, the drug costs about 9 million won per month. She is receiving partial support through a reimbursement program run by the Korea Blood Cancer Association, but the cost is a heavy burden to sustain for two years.
The small cell lung cancer field has recently emerged as a battleground for new drug development, as drug platforms have diversified beyond immunotherapy to include bispecific antibodies targeting DLL3 and antibody-drug conjugates (ADCs). According to global market research firm DelveInsight, more than 100 companies worldwide are currently conducting clinical trials of new drugs in the small cell lung cancer field. "Significant changes are also taking place in the treatment of small cell lung cancer, with hopeful results being reported in clinical trials of ADC drugs that target specific markers on the surface of cancer cells," Kim emphasized. "If a new drug that can prevent recurrence is developed, we may come closer to the goal of a cure."
