Would my doctor be able to see whether my lung cancer has spread to my lymph nodes on a ct scan?

Not definitely: Clinical stage refers to our best guess based on imaging studies, such as chest ct, pet/ct and brain mri, and minor procedures, such as mediastinoscopy, lung biopsy and something called endobronchial ultrasound needle biopsy, or ebus. Ct scan alone is not very sensitive for detecting cancer in lymph nodes.

Yes, but with just a: Little more accuracy than a coin-flip based on size. Ct's miss small things, and falsely label benign things cancer. Proving nodal positivity is helped with pet scans, endoscopic ultrasonography with esophagoscopy or bronchoscopy, and sometimes surgery. Why the fuss? If nodes are +, the role of surgery is limited, and surgery is no picnic, and despite trying to prove its benefit, we're not sure.

Not really: Agree with dr cooke and others. A ct scan can tell you if the nodes appear to be abnormal. Ct scan does not diagnose cancer and can not tell you if there is cancer in the lymph nodes. If you have cancer, abnormal nodes may or may not be because of the cancer. You would need tissue/node biopsies to determine if there is cancer in the nodes.

Not with certainty: If there were enlarged lymph nodes on ct, that would be very suspicious for lymph node metastasis. Unfortunately, a normal sized lymph node can still have cancer cells in it, so ct is not specific. Pet/ct is somewhat better, since it looks for increased metabolism as well, but it also can miss tumors that are very small (<5 mm if very hyper metabolic, <1 cm if less hyper metabolic).