Removed lung tumor containing cancer cells

A removed lung tumor (6mm in size) contained cancer cells.  Person is now cancer free per surgeon and oncologist.  Oncologist is having slides reexamined for something that may show that the cancer cells contain something??? that tremendously increases the possibility of a cancerous tumor reappearing and chemo should be administered as a preventative.  What is that something that could appear in the review of the cancerous cells?

[Dr Santos]

Hi,
How are you? Definite diagnosis is done through biopsy of the tumor. The staging or possibility of metastasis is determined with examination and evaluation of the cells obtained. A second opinion is often done to make sure that the cancer cells are within the cell and tissue and not  in other cells outside. It is best that you discuss this with the attending physician for proper evaluation.  Factors such as  the symptoms present, medical history and diagnosis are important considerations also. Take care and do keep us posted.