Mrs. Lan, a 60-year-old patient, spent a year with a cough that brought up phlegm and came with wheezing. She was treated according to a standard asthma protocol, but the treatment never made her better. Doctors have now given her a different diagnosis: mucinous lung cancer, a mucus-producing form of the disease. Her case shows how the warning signs of a serious illness can look exactly like a common, manageable condition. Symptom for symptom, nothing about her year-long complaint signaled cancer right away. The headline captures the mistake in one line: what was taken for asthma turned out to be lung cancer.