My friend has a lung tumor that did not fully go away with chemo so what is next step?

The only: Lung cancer i expect a complete response to is small cell. The next steps vary depending on what the plan was: was t given before surgery? Radiotherapy? Was the expectation that the chemotherapy was curative? Go with him to the medical oncology visit scheduled to review the tratment plan, and the next steps in work up of response, and plans for further treatment.