Hello from JustAnswer. This is Dr. Love and I will be assisting you today.
While it is true that people with lung cancer are at increased risk of developing pneumonia, the vast majority of cases of pneumonia happen in people that do not have lung cancer. Even in someone with a history of cigarette smoking, the vast majority of cases of pneumonia occur in people without lung cancer.
It is also common for pneumonia to get into your system in other ways. In some people, the germ from the pneumonia actually started in the head, and then traveled into the lungs. We can also grow the germ from the pneumonia in cultures of the blood stream in some people with pneumonia, which shows that the germ has gotten into the blood stream. So, it is not surprising that lymph node swelling occurs in the neck.
Pneumonia is so common that we typically are not concerned about lung cancer unless there are other signs that are worrisome for lung cancer or if the pneumonia does not clear with antibiotics. The fact that you are still having a significant cough is not a sign that the pneumonia will not clear with the antibiotics. The inflammation in the lungs associated with the pneumonia will commonly takes several weeks to completely resolve, even after all the germs are killed.
It is also worth noting that the azithromycin in the Z-pak is incorporated into white blood cells in your body that your immune system will send to the site of infection, so the antibiotic effect will continue for about 5 days after you take all of the pills.
A chest x-ray may detect lung cancer, but can only detect cancer of a certain size. If something were seen that was worrisome for lung cancer, though, they would have commented upon it. Subtle refers to only small or little changes in the chest x-ray, but the chest x-ray can lag a day or two behind the clinical symptoms, so subtle changes does not necessarily mean that the pneumonia is mild.
Therefore, at this point, there is nothing in your description that is worrisome for lung cancer. It is appropriate to see if the pneumonia continues to improve, and as long it resolves, there is no reason for you to be concerned about lung cancer.
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