Chest x-ray of cancer. Squamous cell lung cancer state IIIa. Squamous cell lung cancer begins in the large bronchi and remains localized in the chest for longer periods than other types of lung cancer. It is the only type of lung cancer that undergoes phases. The precancerous phase can last for years. Here, the cancer seen here is in stage IIIa. Stage III means that the cancer has spread to the: chest wall, diaphragm near the lung, lymph nodes in the area that separates the two lungs (mediastinum), lymph nodes on the other side of the chest, or in the neck. Stage IIIa means that surgery can be performed, while stage IIIB means that surgery cannot be performed.