My husband has a non-small-cell lung cancer nodule in right/remaining lung?

7 years ago my husband had a left side pneumonectomy for non-small-cell lung cancer.
Yesterday the doctor told us that his latest CT scan shows a nodule in the right/remaining lung.
What percent chance is it, that the nodule is NOT cancerous?
If it is – will this be treated as a recurrence or as a new cancer?
How will this be treated? Will chemo therapy be effective?